Super Volcano in the Backyard: The Valles Caldera Marathon

Some things will never change. Some things will always be the same. Lean down your ear upon the earth and listen…..All things belonging to the earth will never change–the leaf, the blade, the flower, the wind that cries and sleeps and wakes again, the trees whose stiff arms clash and tremble in the dark, and the dust of lovers long since buried in the earth–all things proceeding from the earth to seasons, all things that lapse and change and come again upon the earth–these things will always be the same, for they come up from the earth that never changes, they go back into the earth that lasts forever. Only the earth endures, but it endures forever – Thomas Wolfe, in You Can’t Go Home Again (1940).


Ariel view of the Valles Caldera and Jemez Mountains. This view is taken from a small plane at an elevation of 14,000′ looking south-southeast across the Valles Caldera. Photo by L. Crumple. (Click on pictures to get full sized view)

There are numerous influences in my childhood that propelled me to a career in the Earth sciences;  a father that loved to prospect and collect minerals, hundreds of family camping trips to the most interesting geologic province in the world (the Rocky Mountains!), and a progressive high school that offered a rich course in geology.  In hindsight, one of the most important influences was the fact that I grew up on the flank of a huge volcanic complex, the Jemez Mountain Volcanic Field.  The terrain of deep canyons, flat mesas, and a beautiful grass valley, the Valle Grande, surrounded by ponderosa pine covered peaks frame my childhood memories and help define home for me. The Jemez Mountains rise some 5000′ above the Rio Grande River and are remnants of a massive volcanic system that experienced two “super” eruptions about 1.4 million years ago.  The Jemez don’t really look like a volcano today if one’s idea of an active volcano is Mt. St. Helens or Kilauea – it is a large circular depression surrounded by the high peaks that once where the steep slopes of a series of craters that spewed forth hundreds of cubic km of hot ash. The figure at the top of this column is an aerial view of the Jemez, and the depression and surrounding peaks protect a series of valleys that once were filled with rain water after the great eruptions.  These valleys, or valles in spanish, are a unique feature of the Jemez. These mountains shaped me in many ways.  Out my back door was a riveting geologic panorama that provided an open invitation to explore nature.  Although most of the Valle Grande proper was off limits during my youth – it was a working cattle ranch that we just called “The Baca” in recognition that it was part of a old Land Grant called Baca Location Number 1 –  the surrounding mountains and forest lands were our play ground.


View from within the Valle Grande to the west. The high peak is Redondo Peak, and the smaller rise on the righthand shoulder is Redondito Peak. The Valles Caldera marathon traverses around the base on Redondo on the edge of the Valles.

I learned about hiking, camping, wildlife, and calm call of nature.  I even learned some things about mineral collecting; in general, there is not much “mineral wise” in the Jemez, with the one exception. My first vehicle was a hand-me-down four wheel drive Toyota Land Cruiser.  Not many things worked on it (including the gas gauge which more than once left me stranded), but it did afforded me the freedom to explore the Jemez on my own.  My favorite trip was to the ghost town of Bland, a short-lived gold mining center located a few miles south of the Valles Caldera.  The mineral deposits were not formed by the volcanic processes that built the Jemez Mountains, but were from an earlier epoch of magmatic activity that injected quartz dikes into surrounding bedrock.  The Jemez volcanics covered these dikes, and later, through the randomness of erosion, were exposed in a narrow canyon (Bland Canyon).  In 1893 the first of a dozen claims was staked on these dikes for gold and silver.  A rush ensued, and soon a town was built and the population grew to more than a 1000 people.  The town was named Bland in honor of Richard Bland who had advocated for the governmental purchase of silver, and in turn, that bullion was minted into silver dollars.  The Bland act, and further requirements for the government to purchase silver (in particular, the Sherman Silver Purchase Act) were repealed in 1893 causing a collapse in silver prices — just as the mines in Bland were being discovered.


The boom town of Bland, circa 1900. Many of these same building were identifiable in the early 1970s when I searched for artifacts (with some success) and traces of gold or silver (without any success!). Unfortunately, all traces of Bland were destroyed in the 2011 Las Conchas fire – it is even impossible to find most of the old mine dumps.

I drove to the ghost town of Bland every chance I got in the early 1970s.  There was a “back way” in that required delicate 4WD navigation;  I was rewarded with a harrowing journey through the Jemez Mountains, and a chance to search through all the old building looking for artifacts and the mining dumps for some sign of gold or silver.  Mostly my searches were unsuccessful, but I had taste of the treasure hunter.


An insulator I collected near Bland in the early 1970s. The screw on glass has a patent date of 1893.

In the year 2000 the Federal Government purchased the “Baca” and it became the Valles Caldera Natural Preserve.  The charge of the Preserve was to remediate the effects of logging and cattle/sheep grazing, and eventually make the Valles Caldera a multi-use facility.  Although access is still carefully controlled to the Valles it has become the home to several special events.  In 2006 it became the site of a trail run – first a marathon, and later a half marathon and 10 km run were added.  The course has changed over the years, and a fire in late May of 2013 forced a change to a partial out-and-back route. The chance to run in a certified super volcano, only a few miles from my house is a huge draw – the Valles Grande Caldera Runs are a geologist’s dream.


A recent NASA satellite image of the Valles and Jemez Mountains (click on the map to get a large, and clearer view). The circular depression of the caldera is obvious; left of the depression (east of the caldera) is Los Alamos. The brown-gray color is due to the denudation of the ponderosa pine and other vegetation after the 2000 Cerro Grande and 2011 Las Conches fires.

The volcano in my backyard

The Jemez Mountains and Valles Caldera are a spectacular sight from space. The satellite image above shows the circular depression that is about 13 miles across that formed after a series of very large eruptions of ash-flow tuffs emptied a large, shallow magma chamber.  Nearly 800 cubic km of ash were propelled from various volcanic vents, and the “hole” left by this erupting ash caused the volcanic edifice to collapsed back into itself producing a broad valley. Later, renewed magmatic activity pushed rhyolitic magmas up through the fractures formed during the collapse, producing a ring of domes breaking up the original valley into smaller, isolated valleys.  The largest of these magma extrusions, known as resurgent domes, is Redondo Peak, which has an elevation of 11,258′ and towers some 2500′ above the valley floor.  Redondo Peak is not a volcano – it was not “erupted” but extruded from the magma chamber beneath the Valles much like tooth paste would be extruded from a tube as it is slowly squeezed.

Vallea cauldera section 700

Geologic evolution of the Valles Caldera. The Valles volcanic center was active for 12 to 13 million years before a pair of major eruptions (1.5 and 1.2 million years before the present) caused the edifice of the volcanic system to collapse forming a large circular depression. Eventually this depression was dotted with a number of volcanic plugs or domes, forming the mottled landscape of Valles Caldera today (Image from the New Mexico Museum of Natural History).

The Valles Caldera remarkable symmetric, and incredibly well preserved — there were no major eruptions after the last collapse a million years ago to obscure the valley, resurgent domes and ring fractures that were formed during that collapse.  These qualities attracted geologists from around the world, and it has become the archetype volcanic caldera referenced in hundreds of studies and textbooks.  Although the Jemez Mountains were recognize being volcanic by the later part of the 19th century, it was not until the 1920s when C.S. Ross of the USGS visited, and later teamed with R.L. Smith in 1946 that the area was mapped in detail.  This mapping was done in part to understand the potential for supplying the new Los Alamos Scientific Laboratory with fresh water, and whether it was possible to bring a large natural gas line across the Valles to provide energy for my home town.  In 1970 Smith, Bailey and Ross published a beautiful geologic map of the Jemez Mountains and the Valles Caldera (figure below), and was the first map to grace the wall of my bedroom (I wish I could find that original wall hanging, but alas, it was packed away when I left for college and no doubt is today been composted and returned to the soil…).


A section of the Smith, Bailey and Ross map (1970) showing the geology of the Valles Caldera. The yellow domes circling Redondo Peak (the brown color in the center of the figure) are the post collapse rhyolite resurgent domes.  The olive green color is the Bandelier Tuff – the base rock beneath Los Alamos.

The colors of the map hint at the extraordinary history of the Jemez Mountain Volcanic Field (JMVF).  The exact reason that the JMVF exists remains a bit of a mystery; it is located at the intersection of the western margin of the Rio Grande Rift and a trend of volcanic fields called the Jemez Lineament that has been postulated as a ancient “zone of weakness” that allows magma generated in the mantle to rise up into the crust.  I think that it is far more likely that the Jemez Lineament is the lucky connection of dots on a map, and that a more plausible explanation is that marks the boundary between a thick and stable crust (the Colorado Plateau) and thinner, more tectonically active crust.  Irregardless, it is clear that the opening of the Rio Grande rift caused volcanic activity to began about 13 million years ago in the vicinity of present day Los Alamos.  For about 10 million years the volcanism was dominated by basaltic lava flows.  Black Mesa, near Espanola, is one of the most famous landmarks representing this period of volcanism (Black Mesa is about 3.7 million years old).  About 3 million years ago eruption of more silica rich magmas commenced and the Jemez Mountain began to grow — there were probably 6 to 10 major volcanoes that tapped interconnected magma bodies.  These volcanoes conspired to create a major eruption about 1.5 million years ago that erupted what is known as the Otowi Member of the Bandelier Tuff.  Nearly 450 cubic kilometers of ash was erupted over a short period (probably a few years, but certainly less than a few decades).  This resulted in a collapse of the volcanic system, and the creation of the Valle Toledo Caldera.  This caldera is obscured by a similar sized eruption about 1.2 million years ago that ejected about 350 cubic kilometers of ash, the Tshirege Member of the Bandelier Tuff.  On the eastern margin of the Valle Toledo is the highest peak in the Jemez, Tschicoma Peak (elevation 11,561′), an remnant that survived both collapses.  The second eruption, and subsequent collapse created the now familiar Valles Caldera.


Extent of ash fall from the second major Jemez Mountains Volcanic field eruption (1.2 million years ago). Ash has been identified in Kansas and Wyoming, and a large volume of the ash was transported down the Rio Grande (the blue streak in the map down the center of New Mexico).

The widely popular phrase “super volcano” has its roots in the 20th century, but mostly it is a phrase invented by the media around 2002 to dramatize the power of big volcanoes.  By 2003 the phrase appeared in more than 100 stories that covered everything from global warming and cooling to mass extinctions.  The USGS tied the phrase to the Volcano Explosivity Index (VEI), a measure of “explosiveness of eruptions”, and a VEI value of 8 became the definition of a super volcano, and implies a volume of material erupted that is at least 250 cubic km.  There have been 3 super volcanic eruptions in the US in the last 1.2 million years; the Jemez, Long Valley, California and Yellowstone in Montana/Wyoming.  All three of these eruptions resulted in the creation of a caldera.  Of course, our human centric view of geologic time — i.e, a million years is a long time — distorts the sense of “super” volcanic eruptions. Although Yellowstone was a large eruption, it was dwarfed by an eruption 28 million years ago that created the La Garita Caldera near Creede, Colorado.  Over the same time that it took the Jemez to erupt the Tshirege tuff, the La Garita erupted the Fish Canyon Tuff — all 5,000 cubic km of it (more than 15 times larger!).  Despite the size of La Garita,  Los Alamos is perched on the shoulder of a real super volcano.


Comparisons of volumes of eruptions – Yellowstone and the Valles are “super volcanoes”, while more recent eruptions like Crater Lake and Krakatau have to settle for being “big” and Mt. St. Helens is just puny.

The relative tranquility of the Valles Caldera belies its violent history and magnificent history.  The most recent significant volcanic activity in the Jemez is the Banco Bonito rhyolite flow, which is located smack dab in the middle of the Jemez Caldera marathon.  The Banco Bonito is a very silica-rich rhyolite, and filled with large blocks of obsidian.  Although most everyone recognizes obsidian, and thinks arrowheads and black shiny pebbles, the geologist thinks about very rapid cooling of a volcanic rock.  Obsidian is silica glass – same material as a chunk of quartz, but it has no crystalline structure due to the rapid quenching of the hot lava. The Banco Bonito rhyolite was extruded (probably not erupted) 40,000 years ago.  Although the Jemez Mountain Volcanic Field will be active again in the future, it is mainly showing signs of exhaustion, and the likelihood of a future, large scale eruption is extremely small. Running through the Valles Caldera on a marathon is a unique experience.  Laid out along the course is every aspect of a few million years of violent tectonic history.  Ash fall, resurgent domes, ancient lake beds that filled with water in cooler and wetter times.


A view from the southeast to the northwest across the Valle Grande, Redondo Peak, the the Colorado Plateau on the horizon. A little over 1/2 of the marathon course is an out-and-back from El Cajete to Cerro Pinon – right through the heart of the Valles Caldera. Also shown is the head of Bland Canyon, home of the ghost town. Picture from 2011 Nature article on Southwest drought.

The Valles Caldera Marathon

The Valles Caldera runs – there is a marathon, half marathon, and a 10 km – are not classic trail runs per se.  Most of the courses utilize dirt roads that once were used to move cattle or cut timber, and only some short segments are single track.  However, this does not diminish the spectacular setting of the race. It does mean that most people run the distances much faster than a typical trail run (I say “most” because single track versus tire rutted roads has nearly zero impact on my speed – sadly).  The races start at Banco Bonito Staging Area within Valles Caldera National Preserve.  The name “Banco Bonito” is applied to a modest plateau that is composed of the rhyolite-obsidian conglomerate that goes by the same name.  It is easy to find very attractive pieces of obsidian at the starting line — just look down.  There are more than 300 people signed up for the half marathon and 10k, but only about 45 of us toe the line for the full marathon at 7:30 in the morning.


Gathering of the runners for the start of the Valles Caldera marathon. Temperature at the start was 34 degrees, and throughout the day the weather alternated between sun, clouds and occasional grapple. Perfect.

The course for the marathon heads due east, climbing up the Banco Bonito lava flow along a logging road.  The lava flow is probably not obvious to most of the runners as it now is forested, and only along certain sections are there stratigraphic sections exposed.  But the topography of the lava flow is evident;  over the first three miles we climb about 450 feet (not much elevation gain, but enough to slow old runners down).  The pack of runners sorts out pretty rapidly, and good runners like Dave Coblentz disappear with a doppler shift over the horizon.  At the three mile mark the course comes to an aid station on the edge of a large bowl shaped depression — El Cajete.  This is a very significant geologic formation (but not such a significant aid station).  El Cajete is the crater that last had significant volcanic activity in the Valles Caldera.  It is responsible for the Banco Bonito lava flow 40,000 years ago, as well as a massive eruption of pumice sometime after the lava flow.  The pumice fell close to the El Cajete, and dammed the Jemez river creating a lake in the Valle Grande.


Aid station at mile 3 – looking out on El Cajete. If you click to enlarge the photo you can see a herd of elk scurrying across the crater on the right hand side — the crater is big, so the elk look small.

From El Cajete the course drops off the plateau and the run is downhill for 2 miles.  Fast and easy.  Unfortunately, the elevation lost is a penalty for the next part of the race.  At mile five there is a steep climb up a pass between Redondo Peak and another resurgent dome called South Mountain.  In a little bit more than a mile we climb 550 feet to the high point of the race, 9150′.  The top of the pass is a reward, but also a harbinger of things to come since we have to repeat this climb on the return from the Valle Grande.


Course elevation profile. By my watch the course of 25.8 miles long.

From mile 6 to mile 12 the course is in the Valle Grande – well, strictly speaking, skirting around the edge of the Valle.  The grass “meadow” of the Valle Grande is due to the fact that it was a reoccurring lake bed in the last million years, and it is not particularly friendly nutrition wise to trees.  The last time the lake had a significant extent was after the El Cajete pumice eruption, and probably lasted for 4 to 7 thousand years (there have been smaller lakes during damp cool periods usually associated with glacial epochs).  The picture below is a view across the Valle towards Pajarito Mountain.  That summit, all 10,400 feet of it, is the high point of the Jemez Mountain Trail Runs — which will be run a month from now.


A view across the Valle Grande to Pajarito Mountain. The weather alternated between sun and dark clouds through the entire run. The temperature was mostly in the high 40s, perfect for running a marathon.

Running through the Valle is always wonderful.  It is sensational scenery, and mostly flat topography.  At mile 9.4 I get passed by the leader of the pack returning towards the finish.  This means that the leader is about 4 miles ahead of me already.  Once the first runner passes by me it is a steady stream;  strangely, all the runners that are ahead of me look like they are strong and running very easily.  I, on the other hand, am beginning to lose focus and daydreaming of the geology.  Dave Coblentz passes me with a group of 5 or 6 runners at mile 9.7. The course “turns around” is at a point just beyond another resurgent dome — Cerro Pinon.  The milage here is just about 12 miles; there is a mental boost knowing that the “out and back” is done, but I also realize that there are 14 miles to go.  For the next 5 miles I pass by a few runners (a very few) that are slower than me, but mostly see no one.  I am alone – happy, but alone.  The climb back up the pass at South Mountain is brutal, but once that is done I am certain that I will finish the race largely unscathed.  The run down from South Mountain is fast, but as I expected, hard on my legs. The run between miles 18 and 22 is a descent of nearly 800 feet.  It should be fast, but my legs are tired.  There is a great aid station at mile 19, and I stop for way too long to eat oreo cookies.  The descent ends at a broad meadow called Redondo Meadow.  This meadow is an wildlife experiential station, and there are lots of people working in the area.  The course route is always confusing here because there is no real trail across the meadow, and there are meandering streams.  The course is marked, but that means you actually have to pay attention to the flagging (not my best skill – however, I have memorized the maps, so I don’t get detoured).  Once across the meadow the home stretch begins.  A steep climb up the Banco Bonito lava flow, and then a lonely run back to the finish.  I pass a couple of slowest runners of the 1/2 marathon, and try to encourage them (however, they are really tired).


Crossing the finish line – photo curtesy of Petra Pirc. I finish in a little over 5 1/2 hours. Long after the good runners, but happy for the experience.

I rambled into the finish line in a little over 5 1/2 hours.  It is a nice marathon – not exactly a trail run, but much harder than a street run.  The total elevation gain is about 3000 feet and the average elevation along the course is 8400′.  However, it is the geology that makes this run so great.  The Valles Caldera is truly a marvel….

101 spinel twins: symmetry and beauty in silver

The universe is built on a plan the profound symmetry of which is somehow present in the inner structure of our intellect, Paul Valery, 19th century French Poet


Silver, Kearsarge Mine, Houghton Co., Michigan. The specimen is 3.5 cm across. This native silver is a lustrous example of a “weave” of sliver crystals exhibiting spinel twinning. Photograph by Jeff Scovil. Click on any photo in the article to get a larger view.

When I first started building a mineral collection — back about 1960 — the single most compelling criteria for determining if a specimen was a “keeper” or just something for the beer flats filled with colorful, yet, unworthy rocks, was whether there was a euhedral crystal.  My fascination with the perfection of a sharp crystal face is not at all uncommon for beginning collectors.  The fact that nature could take time to construct something so perfect strikes a deep chord; the vast universe created by the ultimate act of violence – the big bang – and ruled by entropy, and inevitable decay, still values symmetry.  I recall an early discussion with my mother on the beauty of spring flowers – I asked her why she thought they were beautiful, and she responded with a joyful exposition on the bright and varied colors and the delicate nature of the pistil, and remarkable symmetry of the petals.  I told her that the petals were exactly like crystals since they are always alike, and must be following some sort of “rules”.

The English word symmetry comes from the Greek symmetria;  in turn, symmetria is a concatenation of  Greek words sun and metron, meaning “together” and “measure”. There is a substantial body of Greek literature that refers to symmetry as  “harmonious and beautiful proportion and balance”.  This philosophical definition of symmetry deviates from the strictly mathematical definition, but still projects the power of something that is predictable and has a geometric balance to be pleasing to the eye.  This “pleasing to the eye” is a euphemism for beauty — hard to define exactly, but beauty excites our aesthetic senses.

To me, there is nothing more pleasing to the eye than a silver specimen exhibiting spinel twinning – repeating patterns of crystals that produces a highly geometric weave.  The photograph at the top of the column is a silver from the Kearsarge Mine, Houghton Co., in the Upper Peninsula of Michigan. The specimen is defined by a central rib — an elongated stack of silver octahedrons, and branches intersecting the this rib at angles of approximately 60 degrees.  In turn, these branches have secondary branches exiting at similar angles.  The repeating geometry yields a specimen architecture that is clean and sharp – an exemplar of what the Greeks meant by symmetry.


Silver, from a locality near Tongchong, Yunnan Province, China. Specimen height is 6cm. The wires are the result of decomposition of acanthite.  Jeff Scovil photograph.

Silver:  a special element

Silver is a remarkable element that can form an array of minerals; about 180 different species.  Thankfully, elemental silver is sufficiently inert to occur in nature and is widely distributed throughout the world.  Native silver is a metal of bright white color; it has the highest reflectivity of any metal.  Silver is also the best metallic conductor of heat and electricity and extremely malleable and ductile. These properties are, of course, a result of crystal and atomic structure, which is a face-centered cube with metallic bonds.  The atomic radius of silver is nearly identical to that of gold – and gold commonly substitutes into the silver crystal lattice.


Native silver crystal forms, from Goldschmidt (1913). The octahedron is most common, although cubes are much coveted by collectors. The bottom 3 figures show spinel twinning.

Silver crystallizes in the isometric system, and although individual, sharp macro crystals are rare, the octahedron and cube forms are most common.  The largest individual crystals are from Kongsberg, Norway, where some octahedrons 3-5 cm on a side grace a few fortunate collections.


Cubic silver in calcite; Kongsberg, Norway.Each of the large cubes are approximately 1 cm on a side.  Jeff Scovil photograph.

As a rule, crystals of silver are equi-dimensional or platy. The platy nature comes from the propensity from silver to twin (this is similarly seen in gold and copper) on octahedral faces {111}.  This twinning is known as spinel twinning and is described below.  The conditions for when spinel twinning occurs appears limited – although silver masses of spinel twins are known from hundreds of locations, there are only three or four localities where this type of silver crystallization is common.  The two most famous localities are Batopilas, Mexico and Chanarcillo, Chile.

By far, the most common form of silver in a mineral collections is the wire – which is a secondary growth from the decomposition of silver sulfides and sulfosalts. Any silver deposit that undergoes supergene enrichment inevitably has silver wire specimens.  The picture at the top of this section of the article is a fine silver wire mass from Tongchong in China.  The wires in this specimen are attached to a very small piece of acanthite, no doubt the host material that provided the silver.  All silver sulfides and most silver sulfosalts will produce silver wire upon disassociation — especially promoted by heating.  Although wires can be extremely interesting and coveted specimens for collectors, there are been numerous cases where the wires were “grown” by unscrupulous collector/dealers and passed off as “natural” specimens.

Beauty in Nature

When I hear the word “beautiful” used to describe minerals by collectors I often ask what they mean.  More often than not, the answers seem wanting to me.  Mostly, it is about color — pink and red minerals are always “beautiful”, but black and brown minerals are “interesting”.  Although color can transfix, and certainly evoke emotion, I can not relate to it as the primary metric of natural beauty.  I am also looking for structure in my surroundings – a window into the soul of nature, order out of the chaos all around me.

A seminal event for me was attending “math summer camp” during the summer between 7th and 8th grade.  The instructor was an outstanding teacher named Jack Gehre, and his focus was geometry and trigonometry. Early in the class Mr. Gehre introduced Euler’s formula; for any normal polyhedron, the sum of the number of faces plus the number of vertices, minus the number of edges always equals 2.  I spent the rest of the summer camp trying to understand why.  I suddenly had a “rule” in nature that I could apply to my mineral collection — a rule mysterious and powerful, but incredibly simple.  It was beautiful.  I did not know much about Euler then, but later in college I was introduced to another “law” by Leonhard Euler — an incredible 18th century Swiss mathematician — that has to be the most beautiful equation in all of nature.  I was in a class on series analysis, and the professor, Alan Sharples, walked in the first day of the semester and wrote the following on the black board:


Sharples said, “this is Euler’s identity, a remarkable assertion.  Prove it.  That is all for this first day of class.”  Turns out that this is pretty easy to prove, but when I viewed this on the blackboard I was transfixed — it was pure beauty.  Imagine three essential mathematical constants – e, pi, and  – combined to equal -1.  Wow – simple, brief, and exact.  To this day I view this as a definition of beauty (Euler’s identity is routinely identified as the one of the most beautiful equations in science).

Euler’s identify may seem a long ways from realm of beauty in the mineral kingdom.  However, to me, they are very much related.  Simple, surprising, and an expression of natural symmetry.


Herringbone silver mass, Batopilas, Chihuahua, Mexico. The Specimen is 3.75 cm across. Jeff Scovil, photograph.

Respect the Spinel Twin

Crystal growth in nature is quite complex; the crystal form, crystal size, crystal chemistry all are expressions of the paragenesis. Crystallization for most geologic materials involves the precipitation of a solid (the crystal) out of a solution or solvent (usually hot thermal fluids, although solutions of nearly any temperature can carry dissolved loads of ions and cations).  Crystals start with nucleation of a few molecules from the solution, and then growth occurs by pulling the necessary ionic components out of solution.  The rate at which individual crystals grows depends strongly on the saturation level of the ions of interest – supersaturated solutions appear to be able to grow crystals at extraordinary rates (at least compared to geologic time!), sometimes at several cubic cm per hour.

It is not clear who first recognized twinning in crystals, but it was first written about in detail by Rene-Just Haüy in his epic tome Traité de Minéralogie, published in 1801. In the beginning part of the 20th century there were a number of studies to understanding twinning in minerals. The classic definition was introduced by Friedel in 1926: A twin is a complex crystalline edifice built up of two or more homogeneous portions of the same crystal species in contact (juxtaposition) and orientated with respect to each other according to well-defined laws. The “well-defined laws” all are based on some simple ideas, the most important of which is that within a crystal core that a least one lattice row (i.e., a crystal edge) is common to two different crystals. The figures below illustrate this concept — the lattice of a cubic crystal is defined by four points, and a plane can be drawn through these points that allows a second crystal to share lattice points but have a rotated orientation. Twinning adds symmetry to a crystal aggregate, most commonly about a rotation axis or reflection across a plane. In the metals copper, gold and silver, a particular type of twin is common, called the spinel twin.

twinning planespineltwin2

Spinel twins are so-named because it is a very common habit seen in the mineral spinel. They are contact twins, meaning that have a planar composition surface shared by two individual crystals; this surface is along an octahedral face (written as {111}), and means that there is a rotation of 180o about the contact plane. This is illustrated by the lower figure above – there are two octahedrons joined along a contact plane, but the top terminations “point” in directions and are separated by 120o. The figure below shows how spinel twins can be flattened, and give the characteristic triangular faces that are seen on platy crystals of silver (and gold).


Notional relationship between an octahedron and a spinel twin producing a triangular type crystal face. This is “notional” in that this is NOT how the spinel twin evolves with time, but rather, a visual guide to compare an octahedron (left) and triangular face (right).

In silver, spinel twinning almost always repeats itself with regularity, producing a pattern that resembles a weave of wires.  The silver at the top of this section of the article is from Batopilas, Chihuahua, Mexico, and is an example of a mass of spinel twins.  Through the middle of the specimen is a series of parallel elongated crystals, and growing “off” these strands are regular strands oriented at 60 degrees (or 120 degrees, strictly speaking). These are all spinel twins – repeating some natural frequency that is due to a long lost geologic condition.  Once assembled, the spinel twins from an aggregate of crystals that has been called a “herringbone” silver in reference to the similarity to the shape of the rib cage of the smelly game fish beloved by the peoples of the Baltic.

Why do spinel twins form in silver?  Under certain ideal conditions, a single large crystal represents a “minimum” energy condition, and thus is due to an important thermodynamic rule — a chemical system will stabilize at state of least energy.  If individual crystals are a minimum energy state, then twinned crystals are by necessity at state of higher energy, and thus should be rare. However, environmental conditions tend to localize energy states; for a supersaturated solution, the crystal growth is extremely rapid, and twinned crystal allow more ions to join a crystallize aggregate faster, thus minimizing a local energy state.  For all “herringbone” silver specimens it appears that the conditions of formation require a supersaturated solution, low in concentrations of sulfur, and extremely rapid crystal growth.  These conditions are relatively rare in most epithermal vein deposits; it is very uncommon to find a spinel twinned silver specimen from the great silver deposits of Colorado, Ontario or Freiberg!


Large silver plate (7.5 cm from side-to-side) from Chanarcillo, Chile. The specimen is a weave of spinel twins – and is my favorite silver specimen in my collection. Jeff Scovil photograph.

The silver pictured above is my favorite native silver in my entire mineral collection.  This is a large “herringbone” plate with a three dimensional repeating pattern of twins.  The specimen represents something remarkable in turns of crystal growth.  The tiniest variations in chemistry or temperature during growth would have truncated the growth of this silver weave.


Close up of the Chanarcillo specimen shown above. The central rib is an elongated chain of octahedrons. Field of view is 3 cm. Repeatedly, silver crystal “twin” off the octahedral face(s). At the very top of the specimen there are identifiable octahedrons.

A close examination of the Chanarcillo herringbone yields views of spectacular detail – endlessly repeating, and shouting the fundamental rules for symmetry in crystals. Along the edges of the crystalline mass you can see individual octahedrons – the termination of various elongated crystals.

Beauty and the pretenders

Rapid growth in silver often produces crystalline masses that are complex.  However, spinel twins are distinct, and uncommon.  Rapid growth often leads to dendritic masses – mostly silver feather patterns or strings of stacked cubes. These dendrites are not spinel twins; in fact, instead of fundamental order, they represent chaotic growth.  Although there is some sense of beauty in the randomness of dendrites, it is mostly through “self-similarity” – various patterns that appear to scale with size.  This is fundamentally different than ordered spinel twins – and in many ways points to disordered processes.  I am always shocked (okay, probably an overly harsh expression of emotion) when I find dealers selling “herringbone” silvers that are in fact dendrites.  That is like marketing hamburger as Filet Mignon.  Similarly, silver wires can certainly be attractive; however, they are products of mineral destruction not construction.  To me, beauty in silver spinel twins is about construction, order, and symmetry.  Defining beauty will allows be in the eye of the beholder — it is just better when there are rules involved.

Tsé Biiʼ Ndzisgaii: A trail run in the Valley of the Rocks with a nod to John Wayne

Monument Valley is the place where God put the West. John Wayne, American Actor, circa 1950.


Post card from the 1950s, part of a series celebrating the icons of the United States. This scene of the Mittens and Merrick Butte in Monument Valley defined the American West for a generation. The Monument Valley ultras follow a course around these iconic sandstone buttes. Click on photos for large versions.

The southern half of the Colorado Plateau stretches from Lake Meade in the west, to Cuba, New Mexico in the east, and is a stunning desert highland of pastel colored bluffs, and exotic wind sculpted rocks. The land is both beautiful and desolate; in more than 80,000 square miles there are only 250,000 inhabitants (more people live around Lake Meade and Flagstaff that the rest of the southern plateau combined), but there are 10 National Parks and 17 National Monuments, 10 Wilderness areas, along with another half dozen parks in the Navajo Nation.  It is also the land that American geologists wandered in the 1860-1880s and their observations shaped modern thoughts about geologic time and the extraordinary patient, but always persistent, force of erosion which eventually grinds even the highest mountains to dust. John Wesley Powell navigated the Colorado River through the Grand Canyon and Clarence Dutton mapped the geology with remarkable insight; these geologic giants were the vanguard of the American contribution of “the second age of discovery” that transformed the mystery of nature into a science.  I love visiting these desert lands; in a crowded and noisy world the Colorado Plateau imposes it’s will of solitude and reminds one of man’s temporary significance. Ulta Adventures runs a series of ultra runs across the southern Colorado Plateau that they call the Grand Circle.  Last year I ran the Ultra Adventures Bryce Canyon 50k – and it was a spectacular run!  The geology was great, the UA staff are wonderful, and course was challenging.  This year I decided I wanted to run the UA ultra in Monument Valley held in mid-March.  No other piece of real-estate has defined the American psyche of “the old west” than Monument Valley.  You would be hard pressed to find any baby boomer that would not immediately recognize the “Mittens” — sandstone bluffs in Monument Valley — as the movie backdrop to scores of films.


Scene from the 1939 production of the film Stagecoach. John Wayne played the Ringo Kid – a criminal that makes good, vanquishes the real bad guys, and of course, gets the girl.

Monument Valley is a tract of canyon lands located about 100 km west of the Four Corners along the Utah-Arizona border. Within the valley there is a 140 square mile park – the Navajo Nation’s Monument Valley Park — that was “discovered” by film director John Ford in 1939 with the release of the classic western Stagecoach. Ford chose Monument Valley because, to his mind, the desolation and isolation of the bluffs and red sandstone captured the essence of the hardscrabble life of the wild west. Ford cast John Wayne as the Ringo Kid, a gunslinger. This roll is largely credited with making Wayne a film superstar – and forever he is pictured across from the Mittens.  There is a creation myth about how John Ford found Monument Valley — it starts with Harry Goulding, a sheep herder and owner of a trading post in Monument Valley packing up and heading to Hollywood with photographs of the scenery as an act of desperation during the crushing poverty of the great depression.  Goulding showed up at Ford’s offices and somehow, against all logic, convinced Ford that he should film his upcoming western in the corner of Arizona that was hundreds of miles from the nearest train station and only accessible by a dicey dirt road.  Ford eventually filmed parts of 6 of his most famous movies there;  other directors followed, and Monument Valley has appeared in more than 100 movies!


Forrest Gump ends his epic run back and fore across the US at Monument Valley. This scene, as Forrest stops, and his followers are baffled, was shot on Hiway 163 looking south to the bluffs of Monument Valley.

It is only appropriate that the rich movie heritage of Monument Valley would collide with ultra runs. The 1994 movie Forrest Gump is the tale of a man’s life that serendipitously criss-crosses 40 years of tremulous American history. I saw the movie in Flagstaff, Arizona when my wife was working on the geodetics of volcanoes at the USGS field office – we loved the movie and it remains one our top ten favorites ever. In the movie, Forrest starts running on October 1, 1979 to ease the pain of rejection by his true love. He ends up running for 3 years, 2 months, 14 days and 16 hours, and covered 15,248 miles (crossing America at least 4 times) – no ultra runner has ever equaled the trail brazed by Forrest. Forrest ended his run at Monument Valley – he just stopped, and decided the run was over, and it was time to go home.

What a perfect setting for an ultra run; geology, history, and the termination point for the greatest ultra run ever.

View from the start of the race — the day before. The west entrance to Monument Valley is guarded by three erosional remnants. From the left, West Mitten, East Mitten and Merrick Butte.

Running on Ancient Sand Dunes Monument Valley refers to a large swath of landscape along the Arizona-Utah border, but most people associate the name with a modest 3 by 5 mile drainage basin. This basin stretches from the world famous Mittens in the north to Wetherill and Hunts Mesas in the south. The name “Monument Valley” first showed up on maps in 1917.  Who exactly was responsible for that moniker is lost to history, but the name is appropriately descriptive; the view down the valley is filled with monoliths and buttes that are the erosional remnants of a thick layered cake of sedimentary rocks that were deposited by water and wind nearly 200 million years ago.  The Navajo name for the valley is Tse’Bii’Ndzisgaii, which translates approximately to Valley of the Rocks (at least my Navajo friend tells me this – others have slight variations).


Satellite image of Monument Valley. This is not a false color image – the land is reds and browns, colored by the strained sedimentary rocks that were deposited on an ancient continent during Permian times.

The Colorado Plateau is one of the most unique geologic provinces on the globe. A huge, broad plain or basin was formed at the margin of the primal landmass that today we call the North American Continent. This “basin” captured the cobbles and shards that resulted from the erosion of the ancient continent. Sometimes the basin was beneath a shallow sea filled with corral reefs and marine life. Other times it was at the edge of an uplifted and rejuvenated continent and was covered by a system of deltas cut by meandering rivers – not unlike the Mississippi delta today. Still other times it was a massive wasteland covered by sand dunes. Over a period of 500 million years this broad area we now call the Plateau accumulated a lithic layer cake; thousands of feet of alternating sandstones, limestones, shales and conglomerates. About 20 million years ago this layered rock cake was uplifted, and subjected to the same erosional forces – wind, water and ice – that had ground ancient mountain ranges to dust.

The stratigraphy of Monument Valley laid bare in Merrick Butte. The lower apron is the Organ Rock Shale, which gives the Valley the ubiquitous red dust. The steep cliffs are the sandstones from the DeChelly formation, and the butte is topped by the Shinarump conglomerate.

The slice of this great lithic cake that is exposed in Monument Valley dates from the Permian Age. The rocks exposed on the Valley floor are the oldest – and are known as the Organ Rock shale (about 280 million years old). This shale was deposited as muddy clays in deltas and swamps. Above the shale is the rock that builds the monuments, the DeChelly sandstone.  The DeChelly is an amazing rock – it is a nearly pure quartz grain sandstone, that is tough and strong, and can maintain vertical cliff faces hundreds of feet high.  The DeChelly was formed from wind blown sand dunes.  The modern day analogy for these type of sand dunes is the Namib Desert along the southwestern coast of Africa.  The desert that made the DeChelly sandstone was long lived — probably 25 million years of blowing dunes. Finally, that desert yielded to a more hospitable environment and rivers returned depositing sandstones and shales, which we call the Moenkopi formation.  About 230 million years ago the last of the rocks exposed at Monument Valley were deposited on top of the Moenkopi, the hard cobbles and boulders of the Shinarump conglomerate. The Shinarump is the “cap stone” on the mesa in Monument Valley, and reason that the softer rocks below have not completely eroded away.


Carving Monument Valley. (from Abbot and Cook, 2007)

The landscape of Monument Valley today is only a shadow of what it most have been a few million years ago.  In a few more million years, there will be no sign of DeChelly sandstone, and all the steep cliffs will have been reduced to rubble.  The unique monuments are a result of the layered cake geology; the Shinarump conglomerate is a difficult rock to erode, and for millions of years protected the “softer” rocks below.  However, joints and zones of weakness in the Shinarump eventually yielded to the relentless rains, frost, wind and gravity, and began to erode forming small washes exposing the DeChelly sandstone below.  The DeChelly is relatively easily eroded, but forms steep cliff faces, making for spectacular canyons.  Eventually these canyons cut down to the soft Organ Rock shale which is rapidly washed away.  The canyons then begin to undercut the DeChelly, and the stout sandstone collapsed in rock falls and avalanches. What is left are isolated buttes, mesas, and rock towers. When you run through Monument Valley your view is one of the distant past.  The vertical cliffs demand your attention; they tell a story of time when huge sand dunes moved slowly across the edge of a continent.  There not many fossilized bones in the DeChelly, but there are numerous fossilized track ways of Permain Age creatures (both vertebrate and invertebrate).  The ultra runner today may find the course difficult, but the arthropod racers of 260 million years ago had it much worse.

Sunrise over the Mittens, moments before the start of the race. The runners started the run with a traditional Navajo prayer, facing east to the rising sun and the start of a new day.

Race Day The Monument Valley Ultras — 100 miles, 50 miles and 55 km — all start near the Monument Valley visitor center that sits on the lip of a small cliff overlooking the iconic Mittens.  The runners gathered at 6:45 am for a traditional Navajo prayer welcoming the new day. The prayer, the approaching sun rise, a perfect temperature of 39 degrees, and the energy of the runners creates an emotional aura.  Two weeks before the race, Monument Valley received a record snow fall during a late season storm.  There was some question as to whether the race would follow the traditional course as flooding from the melting storm closed much of the Valley.  However, everything reopened days before the race;  the 55 km course followed a quick descent along a sweet single track that looped around the West Mitten before joining the main Monument Valley tour road.  For the first couple of miles I run a pace of about 9;45 minutes per mile – a little faster than I want given the long day ahead, but there never is any way to calm the emotion! One of the biggest surprises to to me in the first couple of miles is seeing the Mittens from all angles.  Although they look like large buttes, they are actually very thin monuments.  Viewed from the start of the race the West Mitten is a couple of hundred meters across, but  when I pass the western extreme I see that the West Mitten is only a few 10s of meters wide. Although the race started in the glow of pre-sunrise, soon the sun is lighting up the cliffs of DeChelly sandstone.  The reds and browns glow – the promise for a great run.

The rising sun lights up Mitchell Mesa – the runners will have to climb that Mesa later in the day. Picture is from the main Monument Valley tour road, about 3.5 miles into the run.

There are a few tour vans on the Valley road, and tourists are busy taking pictures in the early morning light.  I roll into the main aid station, called Hogan, at 58 minutes.  The total distance covered is 5.75 miles, so I am feeling pretty good.  The 55 km course is shaped like a 4-leafed clover with the Hogan aid station at the center – I will pass through it four times today.  I am trying to run the course today with minimal aid station support – I only want to refill my water bottles, and I carry all the food I will need.  Turns out this is not a great idea – the food looks pretty good at Hogan!

Running into the Hogan aid station — the hub of the 55 km course. I end up visiting this aid station four times during the run.

After a quick fill of my water bottles (and longing gazes at the food – I decide to stick to my plan, and eat a lemon wafer I am carrying), I start the second clover leaf, a relatively short 5 mile loop, almost all on a wonderful single track.  I roll back into the Hogan aid station at 2 hours (10.5 miles), and began a much longer loop towards Hunt’s Mesa.  The first couple of miles are along the Valley road, and pretty easy.  However, the course then begins to follow a very sandy trail/road route.  I had hoped that the recent snowfall would have made the sand semi-compact and easier to run.  Wrong.  The fine grained sand does not hold moisture, and it is a leg burner!  The course passes a series of slender monuments – the tallest of which is called the Totem.


Standing in front of the Totem – a slender monument, about 14 miles into the run.

I ponder the fate of the Totem; it is an inverted pendulum, and will eventually fall.  It is clear that there has not been any significant earthquake activity for a couple of thousand years near Monument Valley, or the precarious nature of Totem would most certainly have caused it to tumbled.  I guess it will stand for a few thousand more years.  Assuming there are ultra runners in a few more millennia, they will not experience the Totem. Miles 14-18 are sandy.  The cliffs of the DeChelly sandstone are rounded by the abrasion from the winds.  Today is a rare and fortunate day – little wind.  The wind of Monument Valley picks up the fine gains of sand and silt that had eroded from the Permian sediments and slams them into the cliff faces.  This constant assault eventually carves the rocks into bridges and arches.


Wind is a very powerful erosion agent, and its effects are well represented in Monument Valley along the race course. I first was introduced to modeling saltation (the lifting of particles by bouncing along a surface) 35 years ago in graduate school.

The route takes us to an amphitheater-arch call the “Big Hogan”.  It is a wonderful example of the power of saltation.  The wind has carved an amphitheater, and at the top has cut an arch – like the smoke hole in a hogan, hence the name.

Approaching the Big Hogan – an amphitheater that has a small arch in its ceiling. Sandy running, but the scenery is great!

The route eventually loops back to the Hogan aid station.  The mileage for the third visit is almost exactly 20 miles.  My time is 4 hrs and 6 minutes.  A little slower than I planned, but considering the sand and all the time I took out to take pictures, I am pretty much on schedule.  Once again, I look at the great selection of food laid out at the aid station and regret my stubborn dedication to minimal support.  Out of the Hogan aid station the last loop is an out and back to the top of Mitchell Mesa — before me is the most difficult climb in the run. The trail leads west along a road cut to support a uranium mine on the the top of Mitchell Mesa back in the 1960s.


The location of Mitchell Mine, a uranium mine that operated between 1962 and 1965. The last push of the Monument Valley utra is a climb up to the top of Mitchell Mesa on the road built to service the mine.

During the uranium frenzy of the 1950s, amateur and professional prospectors fanned out across the Colorado Plateau in search of the metal that fueled the nuclear age.  There are numerous small uranium deposits located in old river channels within the Shinarump formation.  These old channels captured carbon debris – trees, branches, decomposing leaves, etc. – which in turn served to precipitate uranium out of circulating ground waters.  One of these ancient river channels cuts across Mitchell Mesa, and was mined briefly in the period 1962-1965.  The mine’s operation came to an abrupt end when the operator, Robert Shiver, accidentally backed the ore hauler he was driving over a cliff, and tumbled more than 450 feet into the valley.  The same cliff that took Shiver’s life is the one that we have to climb to get to the top of Mitchell Mesa!


A sample of the uranium-vanadium mineral tyuyamunite from the Monument #2 mine – located across the valley from the Mitchell Mesa mine, and located in the same ancient river red. The tyuyamunite is replacing a log that had become stranded in the river channel.

The ore from the mine on Mitchell Mesa was primarily Tyuyamunite – a rare uranium-vanadium oxide (chemical formula: Ca(UO2)2V2O8·(5-8)H2O).  Like many uranium minerals it is colored canary yellow.  The picture above is a sample of Tyuyamunite that was found across the valley on Hunt’s Mesa.  I don’t see any sign of mineralization as I grind my way up the mesa…. The climb really begins at mile 23; there is a rocky and relentless pitch that ascends 1200 feet in only a mile.  I had visions that I would bound up the winding trail – wrong.  It takes me 30 minutes to get to the top, and my quads are burning.

Top of the climb up Mitchell Mesa, looking back at the narrow canyon that the trail runs up. You can see the faint track of the trail along the Organ Rock Shale in the center of the photo. It is hard to do the difficulty of the climb justice with a photo.

The run to the northern end of Mitchell Mesa is physically easy – but the views into the valley are breath taking, and I find myself drifting into tourist mode.  Mitchell Mesa and Merrick Butte are named after a pair of prospectors that were murdered in the Valley in December, 1879.  Charles Merrick had supposedly found three crude smelters built by Ute Indians to recover silver.  Merrick recruited Henry Mitchell to help him find the source of the silver; legend has it that they indeed did find a rich deposit, and the prospectors were heading home with ore samples when they met their untimely demise.  For years treasure hunters have searched for the lost Merrick-Mitchell mine, but it remains lost.

West Mitten and Merrick Butte from the top of Mitchell Mesa. The views from the mesa are spectacular.

The run along the top of the mesa is only about a mile long, but it is difficult after the long climb.  There are patches of snow in the shade of trees, and I stop twice and fill my hat with a couple of handfuls of snow.  It is now about 64 degrees (at least according to my weather app), and I am really overheated.  The melting snow cools my hot head, and steels me for the last 9 miles of the run.

The end of Mitchell Mesa and the turn around point, mile 25. The view looks down to the starting and ending point of the race – only about a mile away, and 1000 feet below. Unfortunately, I have to turn around, run a little under 9 more miles to get to the finish.

The turn around point is the end of the Mesa.  There is a hole punch that you apply to your bib, and turn around and retrace your steps back to the Hogan aid station.  The view from the turn-around point is down to the finish line — so close, yet so far.  I am pretty tired at this point, and my pace is slow.  I pass lots of runners still making their way to the turn-around point, and I realize that although I have been pretty much running alone for hours, there are people that are going to finish several hours after I do.  The descent off Mitchell Mesa is much more difficult than I expect – no springy legs hoping from rock to rock for me!  I get to the Hogan aid station for the final time about 7 hours and 14 minutes.  There is still a little less than four miles to go – argh. The last part of the run is completely along the Valley tour road.  Unlike earlier in the morning, the road is now heavy with traffic.  The speed limit is 15 miles per hour, and many of the cars and tour vans honor the limit, which minimizes the dust.  However, every fourth or fifth car comes zooming by, and stirs up a chocking cloud of red dust.  I really hate this part of the run, and curse at drivers that are obvious to the runner’s fate.  The last two miles of the run are a steep climb back up to the lip of the cliff where the race started at dawn.  I finish at 8 hours and 10 minutes by my watch – 40 minutes slower than I planned, but I am just happy to done!  My watch says 33.5 miles, so it is just short of 55 km. Within a few minutes of rest I begin to think about how great the run was, and even the dust of the tail end begins to seem not so bad.  A wonderful place to have a trail run.

Homage to Gump: Standing near the point north of Monument Valley where Forrest Gump decided he had run enough.

My Forrest Gump Moment I discovered trail running late in life.  Not mountains, geology, the solitude of towering peaks and deep canyons – those have been with me since my earliest memories.  But trail running is a too recent passion, but has allowed me to experience calm even as my muscles ache and I experience true exhaustion.  I am not a competitive runner – oh sure, I wish I was fast, but my age and athletic ability preclude even the allusion of “competitive”. So, why run as hard as you can during an ultra run if you have no chance of being competitive?  Because it is a grand challenge – ultra train races are hard, and pushing your limits are rewarded with the knowledge that you accomplished something difficult.  That sounds a bit trite, but doing difficult things, accomplishing goals, are a reality check on realizing one’s potential.  Like most everyone, I have much grander goals in life than just running long distances on dusty trails;  I want to make a difference in the world, I want to discover, I want to make right.  Those goals are pretty hard to evaluate except post-mortem, and once I am dead I don’t much care.  But doing difficult things allows me to center; accomplishments are mileage posts along the way.

This past January I had my annual physical (I will soon be 59).  Once you pass the half century mark the ritual of the annual physical is aways approached with trepidation.  Most American medial studies define “old age” as an onset of a plethora of symptoms, usually beginning sometime between 60 and 70 years.  The most frightening of these symptoms is the decline of cognitive abilities – slowing down of the brain and gradual memory lose, for example.  Everyone is different, and the decline is certainly a broad spectrum, but just as erosion will eventually wear down Mt. Everest to a nub, brains do wear out.  So, at each annual check up I listen attentively to my doctor hoping to hear that I am amazingly young for “my age”.  My check up in January started more or less as always – I have great heart function, good cholesterol, I seem to have good hearing except when my wife asks me to do something, still have most of my hair, etc.  However, when the final part of my blood test was discussed my doctor said that my thyroid was pretty much kaput.  I was diagnosed with hypothyroidism – an under active thyroid – a little over a decade ago.  I have been taking levothroxin everyday for that decade.  This is a synthetic hormone replacement;  over the years my dose of levothroxin has been increased, so it was clear my thyroid was declining.  I did not receive the news of “kaput” well – I was assured that this is okay, but I needed increase my medication, and monitor it closely.  Hypothyroidism is not particularly rare – a few percent of Americans experience it, and both my parents had it.  But it does have consequences – the thyroid helps regulate many functions in the body (including hair loss, which I appear to be immune to), but to athletes it is the key to fatigue, and to recovery from endurance events.  In fact, there is a mini-scandal in world of endurance racers with the suggestion that some elite runners are using levothroxin to enhance performance.  That has never been my case! But now I began to question if I would be able to truly run, bike or swim anymore.  Was this the onset of old age for me?

The Monument Valley ultra was my first race since my new medicine regime. As I lined up on the start line I could not help but wonder if I could actually do the race.  However, I ran it just fine (well, my legs are not so sure it was just fine).  Unlike Forrest Gump, I am not ready to stop running.

The Goose Necks – meanders on the San Juan River about 20 miles north of Monument Valley

The Glue Does Not Show: Mineral restoration and specimen value

Shades of grey wherever I go
The more I find out the less that I know
Black and white is how it should be
But shades of grey are the colors I see

Billy Joel, Shades of Grey, released 1993.


Stephanite, Husky Mine, Mayo Mining District, Yukon Territory, Canada. The crystal group is approximately 6.3 cm across, and outstanding for the locality; Husky Mine polybasite and stephanites typically have an iridescence that it probably caused by light reflection/refraction in a very thin coating of an unknown silicate. Jeff Scovil Photo.

In the mid 1980s I was first asked to be a judge of the competitive mineral exhibits at the Tucson Gem and Mineral Show. At that time the TGMS competition, and its two top awards – the McDole Trophy (best case of minerals entered into competition) and the Lidstrom Trophy (best individual mineral entered into competition) – were considered the pinnacle of the mineral world. The winners of these awards looked like a “Who’s Who” of the mineral collecting community, and every year the competition was passionate and savage. The rules for the McDole and Lidstrom awards were few; it was based on the judges experiences, biases, and an element of luck on who decided to enter the competition. The judging for the McDole and Lidstrom awards was also a “discussion” rather than some type of formal poll — a judge with a domineering personality could filibuster the other judges into accepting his or her opinion.  I recall clearly the discussion around a particular specimen entered into the Lidstrom competition that I was fond of;  “We can’t possibly consider that specimen a best – it has been repaired!”  The pronouncement carried such an air of academic certitude that I immediately agreed.  Of course, it had been repaired!  How could it really be a great mineral specimen if there was some glue involved!

It was not too long after that I began to ponder the absurdity of dismissing anything that is repaired as inherently flawed (on a personal note, now that I have multiple metal parts in various joints, I embrace the repaired).  Repairing a mineral is rather common – mineral extraction is inherently a violent activity, and the very act of handling a specimen introduces the possibility of drops, dings and scratches. But there is still a feeling that repairs should affect the monetary value of a specimen. I don’t think I have ever been to mineral show where I have not heard some version of the conversation between a dealer and a collector where the potential purchaser doesn’t ask for a significant discount because the specimen has been repaired.  The stephanite pictured at the top of this article is a fantastic complex crystal from the Husky Mine in the Yukon Territory, Canada.  I first committed to buying this piece for my collection around the year 2000.  However, when I went to go pick it up from the dealer I opened the box and the marvelous sample of “brittle silver” was in three pieces!  The stress of transport had caused the crystal to part along inter-growth boundaries.  I was heart broken, and walked away from a masterpiece.  The dealer repaired the piece expertly, and eventually I was able to acquire it.  However, several years later I was transporting it to be photographed and it “parted” again!  Fortunately, it was once again restored, and now sits permanently in my mineral cabinet never to travel again.  I believe it is the best, or one of the best, Husky Mine stephanites in existence, and the fact that it has some clear cyanoacrylate helping to hold it together is inconsequential.

Repair would, thus, seem to be a rather “black and white” issue – restoring a collectable to its original configuration is not fraud or even misrepresentation of nature. Sadly, it is not “black and white”, and repair/restoration has become a spectrum disorder in the mineral collecting world.  Today many consider filling missing gaps in crystals with acrylic resin, buffing away scratches on crystal faces or even heating a specimen to “restore” its primordial color as simply “sophisticated repair”.  Not black and white, but shades of grey.


The Pieta, carved by Michelangelo in the 16th century. The statue has been repaired a number of times in the last 500 years — most recently removing the damage done by a geology hammer (!) wielded by a lunatic.

Real Repairs

The Pieta is a signature masterwork of Italian sculptor Michelangelo, and one of the most famous works of art in history. Michelangelo was only 23 years old when he carved the single block of Carrara marble into a haunting image of a crucified Jesus being held by his mother. By any figure of merit, the Pieta is priceless. Yet, it is repaired – several times! The four fingers of Mary’s left hand were snapped off during a move in the 18th century (restored in 1736).  The most egregious damage occurred in an instant of insanity when Laszio Toth, an unemployed Hungarian geologist attacked. Toth struck the Pieta more than a dozen times with his field hammer, breaking off Mary’s arm, part of her nose, and chipping her face.


Mary’s hand after the Toth attack. More than a hundred fragments of marble had to be reassembled to restore the Pieta.

The repair of the statue was done by a team of 10 people painstakingly reassembling the fragments and filling in voids with a mixture of powdered marble and polyester resin.  When the restore work was unveiled it was claimed that it was impossible to identify where the damage had been.  Some experts suggest that with the passage of time the resin has perceptibly changed color, but in general the repair has faded into history and the magnificence of the Pieta has been restored.

The restoration of the Pieta might be a fanciful stretch as an analogy for mineral repair, but it does frame the philosophy of specimen “value”.  It is highly unlikely that the reconstruction of Mary’s left hand would effect the value of the Pieta if the Vatican decided to part with the treasure;  I can’t imagine any art collector asking the Vatican for a “discount” because the marble was not exactly as Michelangelo carved it long ago.  On the other hand, the restoration process went to great lengths to assure that nothing changed from the original – no added expression to Mary’s face, no extra lamb seated at her feet.


The Alma Queen; a 10 cm, complex rhomb of rhodochrosite perched in a matrix of fine quartz crystals.  This “rock” was found in 1966 at the Sweet Home MIne, and has been called the finest mineral specimen in the world.

The Rhodochrosite Royalty – a family full of plastic surgery

In 1966, a 90 year old silver mine located on the slopes of Mt Bross – one of Colorado’s 53 peaks that have elevations in excess of 14,000 feet above sea level – yielded a remarkable mineral specimen.  The mine was called the Sweet Home, and during its on-again, off-again mining history had periodically produced some of the world’s best rhodochrosite.  However, the standard for rhodochrosite was reset when a mining crew drilled into a pocket and found a 10 cm rhombohedron of cherry red rhodochrosite perched on a slab of pencil thin white quartz. The specimen was purchased by one of Colorado’s earliest fine mineral dealerships, Crystal Gallery, for the princely sum of $2500.  Crystal Gallery was a partnership between Merle Reid and Colorado collector legend George Robertson.  The rhodochrosite ended up in the hands of Peter Bancroft (much to the chagrin of George Robertson), who christen the piece as the “Alma Queen”, in recognition of the mining town a few miles southeast of the Sweet Home Mine (the picture above is “official” photo of the Alma Queen from its present home, the Houston Museum of Natural Science).  In short order the Queen passed through a hands of a number of famous mineral dealers, finally becoming a prized possession of Perkins Sams.  In 1986, Sams sold the Queen to Houston Museum – and a few years later it was being moved and was broken!  Actually, it was not too surprising given that the rhodochrosite has perfect cleavage, and the huge crystal was isolated and perched on matrix.  Fortunately, the crystal was “repaired” – it is impossible to see the glue reattaching the rhomb – and is still considered a masterpiece.

The Alma Queen enticed others to want to return to the Sweet Home Mine and search for more rhodochrosite. In 1991 Bryan Lees and partners began a professional and systematic exploration for mineral specimens.  In 1992 Lees’ operation discovered a 1.5 meter long pocket that yielded incredible — larger than even the Alma Queen — specimens.  Most of the crystals were detached from matrix, jarred from their natural perches by the mining activity.  The largest of the crystals was more than 15 cm across, and was dubbed the Alma King.


Bryan Lees holding the Alma King, just outside the Rainbow Pocket.  The crystal was some 15 cm across!

The Alma King was eventually reattached to matrix, and was brought to the Tucson Gem and Mineral Show in 1993.  I remember seeing the specimen, and was stunned.  I also recall standing next to a old time collector who remarked “too bad it is repaired”.  Wow – my thoughts were not conflicted at all – the repair was sincere and returned a natural masterpiece to it’s rightful magnificence.  It was exactly like the restoration of the Pieta!


The Alma King – repaired. The specimen now sits in the Denver Museum of Natural History.

There is little argument that the repair of the Sweet Home rhodochrosites was the right course of action, and certainly did not diminish the value of the specimens.  However, it also coincided with the crest of a darker tsunami in the collecting hobby that demanded specimen perfection, and art aesthetics overtaking  all other metrics of mineral specimen evaluation.  A significant percentage of the Sweet Home specimens required repair, although the evolving euphemism was “specimen preparation”; a dialog developed around the theme of “returning the specimen to the condition it was in nature”.  This catch phrase has become the a divide between collectors;  those that prize the art of mineral specimens are willing to see flaws removed by polish and resins, while other collectors recoil at any man-induced enhancements and celebrate only that which can be documented “as found”.  This gulf is wide, and brings cries of “fake and fraud” from collectors in the later group when they view many of the world’s best mineral specimens. However, this group of collectors – the old school – is dying away.  Not yet irrelevant, but mostly marginalized.  I am old school.


The cover of the Mineralogical Record, January 2015. On the cover is one of the most amazing tourmaline specimens in existence, and the volume is full of information on the Pederneira mine. What is missing is the painstaking history of specimen repair and restoration – much work is done with added materials.

When a grey line becomes red — and crossed

In the last 50 years the mineral collecting hobby has seen dramatic changes – or perhaps evolution.  What was once the realm of rockhounds is now a glided age of art.  One of the most obvious symptoms of this change is what collectors accept and expect in a mineral specimen.  Repair and restoration have always been important for mineral specimens; however, the definition of repair and restore has changed as prices have escalated.  There has always been a desire to make specimens attractive, but today it is expected that many  specimens are oiled, waxed or sprayed with silicon to enhance their luster and hide their imperfections.  Use of these cosmetic trappings was once a “red line” for collectors – absolutely rejected.  But just like US foreign policy on the use of chemical weapons, that red line was faded to grey.  A tour through the many hotel rooms of the “high end” mineral dealers participating in the 2015 Westward Look Fine Mineral Show in Tucson (February 6-8) reinforces this dramatic shift;  it is fair to say that most expensive fluorite specimens for sale have been treated with oil, every recent amazonite dug from the pegmatites in the high peaks of Colorado has been “juiced” to enhance the luster, and most gem-quality garnets are getting at least a spray of enhancement.  And, further, casual conversation with collectors seems to reinforce that this is what they want.  Perfection is essential for a work of art.


A comparison of “before and after” for a cut emerald. The cut stone on the left is natural, and on the right has been treated with cedar oil (from

The desire to “improve” minerals is a couple of thousand years old.  There is written accounts of Greeks using cedar oil on emeralds to enhance the color.  The purpose of the oil was to fill the flaws and cracks with a material (the oil) such that when light is shined on the crystal there would not be reflections from the imperfections.  The cedar oil had approximately the right index of refraction (about the same as the emerald itself), and low enough viscosity (when heated) to flow into the tiny cracks, but high enough such that it would remain (at least for a while) after treatment.  Today the oil is mixed with a polymer which “fixes” the oil.  There are about a half dozen “restoration” labs in the US that work on minerals, and most have proprietary processes to do essentially the same thing as the cedar oil treatment except for fluorite, sphalerite, garnet, etc.  The science behind these processes is fairly sophisticated — but the treatment is rarely disclosed.


Classic Gary Larson cartoon – Rowing in Circles. This reminds me of specimen restoration – dealers on one side, collectors on the other. Dealers provide what collectors want, and collectors hear from dealers what specimen perfection should be. It is just rowing in circles.

Today it is hard to “lay blame” for the practice of mineral restoration that relies on removing perceived imperfections at the doorstep of dealers.  The nature of the “trophy collector” is to find perfection – and that sense of perfection does not have to be the hand that nature dealt.  Further, it is clear that repair and restoration no longer decrease specimen value, but actually increase value.  As Sir Walter Scott opined: Oh what a tangled web we weave, When first we practice to deceive.

Old School with a New World Order

I love collecting minerals – it is something that I have done with passion for more than 50 years.  I have changed along the way, and the hobby has changed even more than I.  I am deeply disturbed by many of the changes, but that does not make them “wrong”. Just as I am aghast at at what I perceive as the personal values of generations other than mine, my sense of why I collect, and what a mineral specimen means to me, does not have to be shared with others.  The Dalai Lama says: “Happiness is not something ready made. It comes from your own actions.”  I don’t need to change what and how I collect.  It is the science and human story that are codified and crystallized in my minerals. That is why I happily collect that which is repaired and total reject oils and waxes.  A red line.

Seeing Red: The Addictive Allure of Proustite

Beauty of whatever kind, in its supreme development, invariably excites the sensitive soul to tears, Edgar Allan Poe, 19th century American Poet.


Proustite, Chanarcillo, Chile (3.8 cm tall).  Wendell Wilson photograph.  This is the first very fine proustite I obtained for my collection in 1983 from Simon Harrison. Click on photographs to get full-size versions.

There are certain minerals that hypnotize the collector – some with their monetary value, some with their art esthetics, and others with their specimen fame and history. A few appeal to a most primal attraction, a fascination with a rich and distinctive color.   Perhaps no species in the mineral kingdom has a more unique and appealing hue and chroma than proustite; vermillion-scarlet red, appearing to glow under moderately bright light, yet fleeting and fading with time. In Mexico and Chile, miners use the phrase “Sangre de Toro” – the Blood of the Bull – when they encounter freshly broken rock that exposes proustite (or the closely related mineral pyargyrite). These miners celebrated the rock bleeding with rich silver ore.

A “great proustite” is prized in any mineral cabinet, and is considered an essential in a great mineral collection.  However, proustite is enigma to most collectors — beautiful, but it poses very special challenges in terms of curation.  Proustite is well known to darken on exposure to light – mainly sunlight, but also on exposure to the light from most electrical bulbs found in mineral cases. Proustite is probably the only mineral that is proudly advertised as “stored away in a dark box for the last 100 years”. A great mineral that no one every gets to observe? By far, proustite is the mineral I get questioned must intensely about; Can you reverse the darkening? Why does my proustite that I leave boxed up develop a white coating? Can I find display glass for my mineral case that will block damaging light? Unfortunately, the same chemistry and physics that endows the mesmerizing color to proustite leads to its ultimate demise.

I bought my first fine proustite in 1983 at the Tucson Gem and Mineral Show — or more correctly, I bought it late one evening in a dingy hotel room in the Desert Inn located a few blocks west of the TGMS show. The crystal is about 3.8 cm high, and distinctive in its habit; there is no question that it was from Chanarcillo, Chile.  I was introduced to an English mineral dealer named Simon Harrison, who was reported to have a fine proustite.  Simon took me into the bathroom to show me the piece — I recall that the bathtub was filled with ice and cans of beer, and there were mineral flats stacked high — and as I opened the box I was incredibly excited (the crystal is shown at the top of this article).  Inside was a perfect prismatic crystal, fantastic color, and an retired British Museum of Natural History label.  Reality splashed over me as I realized this piece was probably out of my meager means — having just completed my PhD, and was only notionally visualizing what a “paycheck” was.  He told me the price was 3000 dollars – cash, no stink’in checks.  I quickly said yes, but had no clue where I was going to find 3k.  I had three flats of pretty good material in my car out front, and I hoped to sell them in the next couple of days.  I was incredibly lucky that I was able to cajole a dealer to take them all for 3,800 dollars, and I became the proud owner of a piece of ruby silver.


Labels from the Chilean proustite pictured above. The label on the left is from the British Museum of Natural History, and documents that the specimen was purchased in 1865 from Steve’s Sales Room.

I showed my treasure to a number of friends and colleagues and the everyone told me it was great, but that I had to keep it closed up tight in a box, and make sure it never saw the harsh and bright Tucson sunlight (I recall thinking that perhaps everyone was confusing the proustite with a miniature vampire…).  I stored it away, and was happy.  Two years later I opened up the box to show a friend, and I was dismayed to see a white powder near the base of the crystal.  The color seemed as great as ever, but what the heck was the white powder, and what did it portend for the demise of my great specimen?  I removed the white powder with a tooth brush and x-rayed it;  I found it was arsenic oxide.  This seemed mysterious to me, and started me down a path of understanding the complex chemistry and physics of proustite.

Since that first purchase long ago, I have added about 15 proustites to my collection.  I love the species, and even occasionally show the pieces.  I have also probably been asked a hundred times on how to reverse the aging of proustite; sadly, just like the human body, a grand chemistry experiment is going on all the time, and although it is possible to delay the darkening of the crystal, the majestic color will eventually change.  It is not a mystery, but a testament to the wonderful properties of the element silver.


Proustite crystal, 3.1 cm high, Schneeberg, Germanay. This piece is reported to be from Shaft 207, and was probably mined in the 1950s. Jesse La Plante photograph

The next two sections of this post are about the structure and color of proustite – they require some faith in quantum mechanics, and for some readers it is best to just jump to the section on The World’s Great Proustite Localities.

The structure of proustite; silver sulfides and sulfosalts all die and go to heaven

The color of proustite, and the fact that it fades and decomposes on exposure to sunlight, is a result of its chemistry and crystal structure. The chemical formula for proustite is Ag3AsS3, which represents the arsenic end-member of a solid solution series with the “dark ruby silver” pyrargyrite (Ag3SbS3). From a chemical point of view, the proustite-pyrargyrite series is one of the simplest silver-bearing sulfosalt systems. “Simple,” however, is relative when dealing with anything that contains silver. For example, in the laboratory it is possible to make antimony-rich proustite; yet in natural proustite, only a tiny fraction of the arsenic is actually replaced by antimony.


Crystal structure of proustite; shown on the left is the unit cell and in the center is the packing of molecules in a typical crystal shape.  Most proustite crystals are prismatic terminated by the scalenohedron and the obtuse rhombohedron.

The crystal structure of proustite contains covalently bonded As-S3 pyramids, which are stacked in a spiral parallel to the c-axis of the crystal. The silver atoms are situated between the As-S3 pyramids, and link the over and underlying pyramids via S-Ag-S bonds. The figure above shows the packing, and the resulting crystal symmetry. The stack of the unit cells gives a hexagonal structure (in the ditrigonal pyramidal class). Proustite crystals are typically highly modified scalenohedrons – often they resemble “dog-tooth” calcite crystals.

Prismatic proustite crystals, St. Andresberg, Harz, Germany. The cluster of crystals is 1.6 cm across. Jesse La Plante photograph.

The classical representation of the atomic interactions in the unit cell does not capture the complexity of proustite very well;  it is important to take a quantum view, more fully appreciating that the silver atoms are fickle with their attachment to a given sulfur atom.  Below is an individual proustite molecule presented using Einstein’s model for the harmonic displacement of atoms. The ellipsoids represent an envelope of space with a certain probability that the atom is inside; in the figure sulfur is shown in yellow, arsenic in green, and silver is the in silver (of course!).  The silver atoms have the largest ellipsoids — in fact, larger than the entire As-S3 pyramid dimension — reflecting the fact that silver wanders within the structure.


Einstein’s model for the harmonic displacement of the atoms within a proustite molecule. The sulfur atoms are shown as yellow and arsenic as green, and the silver atoms are the large ellipse on the outside. This figure was made by Robert Downs, UofA mineralogist, a structural guru.

In the classical description of the proustite structure a given silver atom interacts with two sulfur atoms (on the over and underlying As-S3 pyramid).  However, if you consider the interactions of a given Ag atom with the neighboring six sulfur atoms, it is possible to define a very distorted AgS6 octahedral group.


Interaction of silver atoms in proustite with neighboring sulfurs. On the left image, there are two bonds which are vertical and the four non-bonded S are in the horizontal plane. In the right image, the view is down the direction of the vertical bonds; the image shows the flat pancake shaped displacement ellipsoid which “cages” the silver. Figure courtesy of Bob Downs.

In this representation two of the S atoms are much closer to the silver atom as compared to the other four (making the silver 2-coordinated). The other 4 sulfur atoms form a plane around the Ag, defining a “cage”.   When the silver atom experiences thermal motion it bounces back and forth between the four sulfur atoms undergoing short periods of being bonded to each of them. This can lead to strong silver migration within the proustite structure — and this is the root cause of the deterioration of proustite on exposure to light!


Figure from the 19th century showing the growth of silver wires from proustite crystals. These wires were produced by spot heating — and look very much like the silver wires from acanthite.

The mobility of silver in sulfides and sulfosalts is described as a thermal effect, which usually leads one to the conclusion that physical heating is required. In fact, the thermal motion of the silver atoms can be excited by radiation, including visible light. When light shines on proustite the unit cell increases in volume; this volume is accommodated in the c lattice parameter, meaning that the distance between the As-S3 pyramids in adjacent layers increases, promoting a reaction that liberates the arsenic which reacts with the atmosphere to produce As2O3 – the white powder that is sometimes seen on proustite. The light also mobilizes the silver, which typically combines with the sulfur to form acanthite. The “darkening” of proustite on exposure to light is actually the surface growth of acanthite and silver.

Proustite cluster from Schneeberg. Specimen is 3.1 cm across. There are a number of silver outgrowths on the proustite. Jesse La Plante photograph.

The chemical changes associated with light degradation of proustite are irreversible. Once the silver migrates and reforms on the surface as a new sulfide, the host proustite is forever changed. The “darkening” of the proustite is in fact a surface coating, and it can be removed with silver cleaner, although this “cleaning” leaves a pitted and damaged surface.

The mobility of silver in proustite is hardly unique; in fact, all silver sulfides and sulfosalts are temperature sensitive. The classic example is the growth of silver wires out of acanthite. Recently, there have been a large number of “constructed” silver wire specimens from Morocco and China where acanthite crystals have been blow-touched to liberate bright curls of silver. The same thing happens to proustite when point heated, something that has been know since the 19th century when the figure above was published (criminal, blow-touching a proustite crystal!).

The color red – band gaps

The structure of proustite is also responsible for its marvelous color. It also requires a detour through quantum mechanics to understand how electrons behave with energized.  Proustite is a semiconductor, and thus its color is controlled by the energy of electrons and the “band theory of metals”.  The main tenet of band theory is that the outermost electrons of the atoms within the mineral belong to the crystal as a whole. For pure metals, such as silver and gold, each atom contributes the electrons in their outer orbits to a “pool”; these electrons are free to move throughout the crystal, and this results in high thermal and electrical conductivity, and metallic luster.  For semiconductors – like proustite – there is a prevalence of covalent bonding, or electron sharing.  This limits the mobility of electrons, and there are gaps in energy between the covalence band and a band that would be required for the true electronic sharing (the conduction band).  The size of this energy gap controls the color of the semi-conductor.


Energy gaps, or bands, in minerals and metals. If the gap is nonexistence, there is no band, and the material behaves as a conductor. If the gap is small, the material is a semi-conductor. The size of the gap controls the perceived color of the material.

For metals, the electron pool absorbs energy from incident light and the electrons are excited to higher energy levels; the electrons return to their native lower energy state and emit a photon of energy proportional to the difference between the excited and native levels.  For gold, the electrons have a strong absorption of energy at 2.3 eV, which we observe as yellow.  For silver, the absorption peak is at about 4 eV, which is closer to the ultraviolet – so all the visible spectra is returned and the metal acts like a mirror. Hence the shiny, nearly white color of the metal.


Color table for semi-conductors. The visible light spectrum covers a range of energies, and absorption is possible at all energies above the band-gap of the material, but not below. If the gap is very small (<1.5 eV) then all the light energies are absorbed and a black color is observed.

For semiconductors, it is only possible to absorb the energies of incident light at all energies above the band gap, but not below. If the gap is very small, the color appears black.  If the gap is very large, no absorption occurs, and the mineral appears colorless.  Diamond has an energy gap of 5.5 eV, well beyond the spectra of visible light. Proustite has an intermediate gap – about 2 eV — and therefore only red light is transmitted; all other colors have energies larger than Eg and thus, are absorbed. Pyrargyrite has slightly smaller gap (the difference between a covalent bond with antimony vs arsenic) and therefore is slightly darker.

The unique hue of proustite is a product of silver-sulfur bonds competing with the arsenic-sulfide pyramids.  Since most silver sulfides and sulfosalts are similarly constructed, they all have a red color.  We tend to think of minerals like miargyrite and polybasite as “black”, but in fact their streak is red.

The World’s Great Proustite Localities

Proustite is known from thousands of localities, but only a paltry half dozen have produce collector specimens of note.  Proustite and pyrargyrite are generally late forming minerals in hypogene (high temperature and pressure fluids) environments, although occasionally there found in supergene (near surface, and typically controlled by meteoric waters) environments.  Proustite is considerably rarer than pyrargyrite; both minerals are typically dispersed in smallish grains within vein systems. The abundance of proustite in world-wide silver localities portends that there should be exceptional crystals from many localities.  However, macro-crystals are quite rare except at Chanarcillo, Chile and near Schneeberg, Germany.

Chanarcillo: The undisputed heavy weight champion of proustite localities is Chanarcillo, Chile.  Between 1850 and 1875 an extraordinary number of terminated, undamaged proustites were recovered in veins of calcite.  The largest of these crystals is reported to be more than 9 cm in length, and hundreds of specimens are known in museums and private collections across the globe that are long prismatic candles of red in excess of 5 cm length.

Proustite (121829-00)

Proustite, Chanarcillo, Chile. This specimen was originally in the Vaux collection, and is now in the National Collection at the Smithsonian Institution. The main crystal is a little longer than 7 cm. Photograph provided by Paul Powhat.

The Chanarcillo deposits are located south of Copiapo, about halfway between Antofagasta and Santiago, Chile, in the Atacama Desert.  In May 1832 a freight hauler and prospector named Juan Godoy was hunting Ilamas when he tired and decided to rest under the shade of an outcrop.  Godoy noticed a waxy vein and began to pry the vein material out with his knife – he later described it as “soft as cheese”. He loaded up two mules with the ore — chlorargyrite — and headed to the nearby town of Copiapo to have it assayed.  Godoy entered into partnership with a friend, Juan Callejos Miguel Gallo, and founded the Descubridora mine.  Rumors of the richness of the strike started a rush to Chanarcillo, and by 1850 there were 1,750 mires in the district.  Unfortunately, the story of Godoy ends sadly, in the way of many prospectors;  Miguel Gallo became immensely wealthy, but Godoy squandered his share of the Descubridora and died a beggar.


Vaux proustite, National Collection, Smithsonian Institution. This specimen, thought to be from the Dolores Mine, is about 4 cm high, and cherry red. The photo was taken by Wendell Wilson in 1972 – at the very beginning of his illustrious career as a mineral artist, photographer, scholar, and editor.

The Descubridora Mine produced the largest and best native silver specimens from Chanarcillo.  Much of the silver occurred as thick wires encased in calcite, but the most characteristic habit is arborescent “flags” or herringbone plates of crystals.  Two other mines produced specimens of note: the Mina Dolores Tercera and the Bolados.  The Dolores is perhaps the most famous to mineral collectors, and during the 1850s the lower levels of the mine encountered a series of vugs filled with proustite, acanthite and chlorargyrite.  The Bolados (named after four brothers who discovered it) contained huge masses of native silver — one of these weighed an estimated 1,360 kilograms, and had to be hand-chiseled from the mine because black powder blasts only dented and bent the lode.  Another Bolados bonaza pocket contained chloragyrite and silver weighing 20,450 kilograms!


Chlorargyrite from Chanarcillo, Chile, about 6 cm across.  I obtained this from Cal Graeber in 1999, and although it is just labeled as “Chanarcillo”, the date of the original label and form suggests it was from the Bolados Mine.

There were 18 major mines in Chanarcillo that produced more than $90 million (as measured in 1875 dollars) worth of silver in aggregate.  Most mining was abandoned by the end of the nineteenth century due to the exhausting of the ore. There were periodic attempts to revive the camp in the camp in the 20th century, but this only resulted in all the dumps being hauled away for processing.  Every trace of mineralization has been chipped away from the tunnels and open workings.  I visited Chanarcillo in 2001, and was amazed how little remained.  The value of the proustite is not lost on the locals; if you travel to Copiapo and inquire about buying proustite, someone will show up at your hotel room with red-colored rock and asking price of thousands of dollars.  Sadly, no new proustite has been recovered in more than a century.


Fettelite crystal group, Chanarcillo, Chile. The largest crystals are 0.7 cm across. Jesse La Plante photograph.

However, there are plenty of Chanarcillo proustites stored away in museums, and occasionally returned to the collector world.  About 12 years ago a large proustite was traded out of the Harvard Museum;  as traded it was an ugly clod. It was a mass of calcite with glimmers of proustite.  The dealer made the trade with the hope that the removal of the calcite would reveal a masterpiece.  In fact, it revealed many masterpieces!  During the cleaning it also revealed some material that looked like red mica.  Testing confirmed it was fettelite, a rare silver-mercury sulfosalt (Ag16HgAs4S15).  Fettelite was only described in 1994, and all the known material was flakes less than .2 mm across.  However, the “cleaned” Harvard piece yielded crystal books to .7 cm!  I was fortunate to acquire the very best of these (before others decided that these should be really expensive since they were the world’s best!).

Proustite, Schlema, Germany. Specimen height is 5.0 cm tall. Jesse La Plante photograph.

Schneeberg/Schlema: The Erzgebirge — translates as the ore mountains – is a fault block mountain range that forms the border between southeastern Germany and the Czech Republic.  For mineral collectors, The Erzgebirge is a mineral locality of mythical proportions;  Freiberg, Marienberg, Annaberg, Jachymov, Johanngeorgenstadt, Pöhla and Schneeberg.  These mines operated for centuries, and gave birth to modern mining geology, engineering and mineralogy.  These mines produced a larger volume of world class silver minerals than any where else on the globe – and  so many of these specimens are preserved because of the rise of gentlemen naturalist that were ravenous collectors in the 18th century had access to these marvels.


The “silver road” – a journey through the most amazing silver mineral localities in the world. The yellow line traces the route from Dresden to Schneeberg. I had the privilege to make this pilgrimage in 1991, shortly after the fall of the Berlin Wall.

Proustite is found throughout the Erzgebirge, but a series of mines in the Schlema valley produced the very best specimens. The town of Schneeberg sits at the western end of a small valley — about 5 km long — that drains into the Zwickau Mulde (river).  Within this modest strip of land sits the Schlema-Hartenstein and Schneeberg mining districts.  Silver was known to have been mined in the area from at least since the beginning of the 15th century, and the first major discovery occurred in 1470.  Within 4 years there were 176 mines recorded to be producing silver.  The most famous of the early mines was the St. Georg; in 1477 a large lode of native silver and various silver sulfides was discovered which is said to have contained 20,000 kg of silver. A large slice of this lode exists today in the Senckenberg Natural History Collections, in Dresden.


A piece of the 20,000 kg silver lode discovered in 1477 in the St. Georg mine in Schneeberg. Photograph by Barbara Bastian.

The mines in the Schneeberg-Schlema area exploit a network of hundreds of veins that vary in size;  the most important are over 2 km in length and 3 meters wide.  The character of the mineralization within in the veins is complex which is the result of the superposition of multiple hydrothermal events over a long period of time — from the Permian to the Cretaceous.  The complex mineralogy is characterized by the metals C0-Ni-Bi-Ag-U.  In fact, the variety of metals also explains the long mining history of the region.  Within 25 years of the first major discovery most of the silver mining had ended, but the region was revitalized in 1520 when cobalt became an important commodity to produce blue glass.  In the early part of the 19th century the focus of the mining shifted to nickel, and by 1830 the uranium became a main mining target.


Proustite, Schneeberg, Germany. Crystal 2.7 cm tall. Jesse La Plante photograph.

After the conclusion of World War II the Soviets invested heavily in the region to mine uranium for their nascent nuclear weapons program. By the end of the 1950s East Germany was the fourth largest producer of uranium, and the Schneeberg-Schlema area is now recognized as the largest vein-style uranium deposit in the world. By the time the mines shut down in 1990 the total uranium production was more than 96,000 tonnes.


Waste dumps from the mining of uranium above Schlema. Photo was taken in 1960 (from the German government agency responsible for remediation).

Although the Schneeberg-Schlema mines had a complicated history in terms of the target metal, a constant through time was the occasional encounter with rich pods of silver ore. Proustite specimens were documented as being recovered from the mines for over 500 years. Many of the best specimens were recovered in the 20th century, and preserved.  Unfortunately, the names of the specific mines are often obscured — in fine Soviet tradition the mines operated post WWII were donated by numbers assigned to the adits or shafts.  The most famous of these shafts was “207” located in Niederschlema.  WISMUT, the uranium mining enterprise, made a gift of several dozen stunning proustites from shaft 207 to the Technische Universität Bergakademie Freiberg (the Frieberg Mining Academy).  These proustites reside in a drawer – hidden from light, but when the proustite drawer is brought out the reaction from collectors is always one of disbelief!

Proustite, Schneeberg, Germany. Crystal height is 3.2 cm. Jesse La Plante photograph.

To Show or Not to Show

Proustite is a marvelous and complex mineral – to quote Winston Churchill, it is “a riddle, wrapped in a mystery, inside an enigma”.  The unique color of proustite demands attention, but each flash of attention under the display lights inevitably permanently changes the specimen.  There is no simple solution to delaying the darkening of proustite — the short wavelength end of the spectra causes the reaction to occur more rapidly, but the lattice will swell with exposure to any part of the visible light spectra. Thus, it is not possible to just install UV glass on a mineral case and assume your fine proustites will glow red for a generation.  On the other hand, a brief exposure to light for an occasional display has little consequence.  Judicious displays — both in frequency and out of direct sunlight – can make poustites objects to behold for at least a hundred years.

El Tour de Tucson: Riding bikes with 8,400 friends

A man on foot, on horseback or on a bicycle will see more, feel more, enjoy more in one mile than the motorized tourists can in a hundred miles – Edward Abbey, in Desert Solitaire 


Looking north across the Tucson Basin in southern Arizona. The El Tour de Tucson is one of the largest biking events in the country – nearly 10,000 riders circle around the “Old Pueblo”.

I moved to Tucson  late in the summer of 1983 to become an Assistant Professor of Geosciences at the University of Arizona.  I spent 20 years in the “Old Pueblo” and lived the academic life, became curator of an outstanding mineral museum, worked on the greatest mineral show in the world (the Tucson Gem and Mineral Show), met my future wife, raised my family and saw my son become a third generation Eagle Scout.  The Sonora Desert is like a cactus in bloom – beautiful but also deadly.  I hated the summers that seemed to stretch from May 1st to the end of October, but the months of November and February are so extraordinary that heaven is the only description that is sufficient.

A few years after I arrived in Tucson I began to ride a bike to recover from knee surgery, and discovered that long rides in the Sonoran Desert were therapeutic both for the body and soul. In the 1990s Tucson was a very bike friendly community, and you could choose rides of any flavor; climb 6500 feet up Mt Lemmon along the Catalina Highway, ride the frontage road near I-10 to the north and easily average 22-25 miles an hour, group rides, and daily commutes.  My first “serious” bike was an aluminum framed Cannondale, and in 1990 I purchased a sweet steel lugged Serotta Colorado.  I entered a number of the centuries, and in 1991 I signed up for one of the premier long rides, the El Tour de Tucson.


The official poster for the 1991 El Tour de Tucson. The route was 109 miles and traversed the perimeter of the Tucson Valley.

The El Tour de Tucson, which had its inaugural event in 1983, is one of the nation’s largest single day cycling events. The father of the Tour, Richard DeBernardis, wanted an epic event that captured the challenge of “riding the perimeter” of a landmark, and circling the Tucson Basin fit the bill perfectly.  In 1991 the event attracted around 3000 cyclists – which seemed immense to me when I pushed my bike to the start line at the Sheraton El Conquistador on the north side of Tucson.  It was  a cool Saturday morning just before Thanksgiving, and riders were segregated in “corrals” based on ability – I was in the massive public corral.  It took me a little less than 5 hours and 20 minutes to ride the 109 mile course that included some iconic peculiarities of the El Tour (there were two “water” crossing that require the cyclists to dismount and carry or push their bikes – mostly the crossings are about getting off the bike, but sometimes they are wet!).  Cyclists that finished the course in times between 5 and 6 hours received a “gold medal”, and I only regretted that I totally bonked the last hour and imagined I barely missed out on a “platinum” medal (it is really unlikely I could have made up the 20 minutes, but that is the power of positive thinking!).  I rode the El Tour again in 1994 when the temperatures at the starting time were much less than 40 degrees and froze, but still did the ride in less than 5 1/2 hours.


Rainfall totals around Tucson for 8 hrs beginning at the start of the El Tour de Tucson on November 23, 2013 (figure made at click on the image for a full size image to see the rainfall totals). The three day storm dumped nearly 3 inches on the Old Pueblo.

When I left Tucson in 2003 I always thought I would return to ride the El Tour often — I did not find the time until 10 years later when a couple of friends from Los Alamos and I entered the 31st version of the El Tour.  We headed out from New Mexico on Friday, November 22, and by the time we got to Tucson it was raining.  It is not unusual to get some precipitation in Tucson in November, but the storm forecast called for a significant chance of rain during the race.

It rained overnight before the race, and was lightly sprinkling at the start of the race.  Cold and wet, I waited at the start line with high expectations — how bad could it be?  Well, it rained nearly continuously for 4 hours.  The map above shows the rainfall totals at stations across the Tucson Basin during the race – many recorded more than 1.5″ during the race.  I never had a more miserable ride – between the rain fall, the spray from other riders, and road grim that comes with big storms, the ride was a major challenge! I did the first 75 miles on pace for a 5:50 finish, but cramped up and limped home in a time of 6 hr 21 minutes, and placed 521 out of 1626 riders (the race officials pulled a large number of riders off the course because the Sabino Creek crossing became too dangerous – and thus there was a much smaller finishing cadre than usual).  After a few hours of recovery, my friends and I vowed to return and conquer the El Tour in 2014 and simply celebrate the most ridiculous and wet ride we just experienced.


Crossing Sabino Creek in the rain in 2013. The organizers closed this crossing about 40 minutes after I crossed over.

The 2014 El Tour de Tucson

The line up for the El Tour begins before sunrise and the sky has a faint red glow associated with the sunlight diffracting from beyond the horizon. 3200 cyclist mill around the starting line in Armory Park near the center of old Tucson just before 7 am start time for the 104 mile race/ride (the distance of the course changes from year to year depending on road construction).  It is always clear that the cyclist come in all varieties — there are expensive bikes, mountain bikes, tiny people, large bodies, and some just strange sights like the fellow in a hot pink body suit.  The Armory Park area dates from the the civil war when Union troops from California established a military camp here, and today it is the heart of one of the oldest Tucson neighborhoods.  It is cool — 38 degrees — as the starting count down begins.  I know I am pretty far back in the corral, right behind a group of riders that are wearing jerseys advertising bicycle accident lawyers (Hurt in a Biking Accident? Call xxxx).  I am not sure if this is some sort of message from father fate, but I am reminded that I really have to be careful over the next 30 minutes.  The countdown from 10 signals the start — and I don’t move for 3 minutes as the mass of cyclist in front of me slowly start up;  it takes another 1 1/2 minutes until I pass the official start line.   The mass of cyclists is amazing.  Finally, I am rolling along and hugging the far left side trying to pass as many of the cyclist as possible within the first 5 minutes.


Starting line corral at 6:45 am. The official starting line is on the horizon of the photograph, and I am in a sea of some 3500 riders get ready for the 104 mile event. A total of about 8400 riders competed in an El Tour Event and 5122 crossed the finish line at Armory Park.

Tucson sits in a broad valley (with an average elevation of about 2600 ft above sea level) surrounded by tall mountains in all directions.  To the east and north are the Rincon and Santa Catalina Mountains, to the west are the Tucson Mountains, and to the South are the Santa Rita Mountains.  Despite the high mountains, the El Tour de Tucson is a relatively flat course – rolling hills, but less than 3000 feet elevation gain/loss for 104 miles.  Of course, this is because of geology!  It is a little hard to examine geology from a bike, especially during a fast moving century, but I have the advantage of knowing about the geology and that makes the ride much more interesting.


Simplified geology map of the area surrounding Tucson (from the Arizona Geological Survey). The red colors are granitic batholith rocks (although sheared). The Tucson Mountains, on the west side of the basin, were once located some 30 km to the east above the batholitic rocks. The Tucson Basin is an alluvial filled down-drop basin and range graben.

The Tucson Basin separates the crystalline cored mountains in the east (the Rincon and Santa Catalina mountains) from the mostly andesitic volcanics in the Tucson Mountains.  Before about 1975 it was assumed that the Catalina-Rincon mountains were simply an uplifted batholith (granitic roots that represented large, mid-crustal depth magma chambers), but there was a perplexing rock fabric that was exposed with the granite that hinted at much more complex geologic pedigree.  Around 1980, Peter Coney (an extraordinary geologist from the University of Arizona) proposed that this fabric was the result of extensive “stretching” of the crust and denuding of the deep seated rocks along low angle detachment faults.  The fabric in the rock is a metamorphic (recrystallization due to extreme stains due to the crustal extension) overprint on the granites.  The Catalina-Rincon mountains became the “type” locality of what geologist coined as metamorphic core complexes (MCC).  When I was a young faculty member at the University of Arizona there was an intense debate on how low-angle detachment faults could form – in fact, to this day, their origin is hotly – and emotionally – contested.  What makes the MMC model so significant for the Tucson Basin is that it provides an mechanism to connect the Tucson Mountains to the Catalina-Rincons;  the Tucson Mountains once set on top of the Catalina Mountain rocks!


A model for the MMC based on the Catalina-Rincon Mountains (from a paper by Spencer and Reynolds, 1996). Around 30 million years ago the crust began an episode of extraordinary extension and the upper crust was transported to the west along a detachment fault. As this detachment fault “uncovered” deep seated rocks, these rocks uplifted creating a large domal structure, which is defined by the crest of the Catalina and Rincon mountains today. The rocks that were “pulled” to the west eventually traveled some 30-50 km.

The start of the El Tour sends the riders for a short jaunt to the south before ending east and crossing the Santa Cruz River.  The Santa Cruz River is a misnomer today – it is a dry ribbon of sand that only comes alive when there a large rainstorms that run off the parched desert landscape.  The Santa Cruz River drainage basin covers a large area in southern Arizona, and eventually empties into the Gila River just south of Phoenix.  Two major tributaries of the Santa Cruz — again, dry sandy washes most of the time – are also crossed by the El Tour.  These are the Rillito River which drains the southern Catalina Mountains, and the Canada Del Oro which drains the northern Catalina Mountains.  Last year all three washes were flowing with brown, churning water; this year they are sandy hiways.


Official map for the 104 mile El Tour de Tucson. In red are a couple of landmarks in the text.

The first 5 miles of the El Tour is all about survival – avoiding accidents and falling water bottles, getting ahead of wandering cyclists, and making a couple of sharp turns with cyclists of mixed experience. There is lots of shouts of “hold your line” – mostly in vain, but survive I did!  After about 15 minutes the rider field is beginning to spread out, and the course turns back east; almost immediately we have our first “river crossing” — a run through the sandy Santa Cruz channel.  The riders have to dismount and wade/walk/trot about 150 yards.  This crossing seems crazy, but it actually spreads out the rider field.


Riders crossing the Santa Cruz — I am in there somewhere. Once you come up the east bank the riders are pretty spread out, and the real cycling begins. Photo from the Arizona Daily Star.

Once I climb out of the wash I quickly get back on my back on my bike knowing that the real ride begins now.  The vistas to the east are spectacular (although, in truth, my glances towards the Rincons are very brief as I mostly worry about other cyclist’s wheels).  The detachment faulting that beheaded the Catalina-Rincons occurred between 30 and 20 million years before the present.  Around 10 million years ago Southern Arizona was subjected to another episode of crustal extension, characterized by fairly steeply dipping faults (in opposed to the shallow dipping detachment faults) and a whole series of down dropped grabens were developed to accommodate the extension.  In the Tucson area a series of high angle faults down dropped the area west of the Catalina-Rincons producing a deep basin.  Subsequent erosion of the mountains has filled the basin with sediment, and the relatively flat topography of the developed area of Tucson belies the 1000s of feet of sediments filling the basin. The fast flat track of the El Tour more or less follows a contour line circling the basin.

A notional model for the formation of the Tucson Basin and surrounding areas (from the Arizona Sonoran Desert Museum). Looking from the north to the the south, the sequence begins 30 million years before the present with the eruption of a large andesitic volcano.

The first hour of the bike ride is mostly uneventful; I averaged 21 miles per hour and pass at least a 1000 riders. The course loops around Tucson International Airport, and eventually turns along the frontage road of I-10. Finally, we turn north off the  I-10 frontage road on to Kolb Road and cross over the massive freeway.  A few minutes after the peddling along Kolb the riders pass through a unique Tucson landmark — the Bone Yard.  Kolb road slices across property associated with Davis-Monthan Air Force Base that is home to the Air Force Materiel Command’s 309th Aerospace Maintenance and Regeneration Group (AMARG) – an organization charged with “dealing” with excess military and government aircraft. In reality, “dealing” with excess aircraft means miles and miles of out of service planes parked in the dry Tucson desert. As I cycled along Kolb I can see planes to the left of, planes to the right (and I am stuck in the middle with a bunch of jokers on bikes). One of my favorite planes in the line up are a few hundred B-52s that have their wings chopped off – all in the name of the START I treaty that required the US and Russians to remove a large number of delivery systems for nuclear weapons.


A 2014 google image of the Bone Yard. The vertical stripe is Kolb Road, the route of the EL Tour, and the line up of decommissioned aircraft stretches for miles.

At about mile 29 the already huge mass of riders merges with the riders that have chosen to ride the 75 mile tour.  The merger is more than vaguely related to a stream being captured by a river; the 1200+ riders that are starting the 75 mile course flow in from the left, but are slower than the passing mass of the 104 mile cyclists, so they tend to form a strip of cyclists that keeps its “identity” for at least a half a mile.  The organizers plan the start times of the shorter routes such that all but the elite riders can arrive at the finish line within about a 2 hour window.  This means that although the long stream of riders gets thinned out by cycling ability and speed it gets repopulated 3 times (for the 75, 55 and 40 route starts) and you never are cycling alone – you get 8400 friends joining you!

A few miles after the merge of the 75 milers the course turns north on to Freeman Road, and begins a 3 mile climb up Freeman Hill, the high point along the El Tour.  The climb is only a few hundred feet, but it serves to break up the pack into much smaller groups.  Freeman Road is the western boundary of Saguaro National Park East, and home to one of the largest saguaro cactus forests.  Saguaro are only native to Arizona and a very small region of California in the US (despite showing up in advertisements for salsa from Texas, Oklahoma, and even New Mexico — sigh), and are a remarkable sight.  The cactus can grow to 70 feet in height, and typically live for more than 200 years.  For the first 70 years or so of life, a saguaro is a solitary green thumb; after 70 years the cactus might grow arms, giving the saguaro an anthropomorphic silhouette.  Riding along Freeman road my state of exhaustion causes me to image the saguaro are a marching army of green aliens.

Saguaro National Park East, ca. 1935. NPS 3423

Image circa 1935 of what will become Saguaro National Park East, right along the El Tour course. The cactus in the foreground about about 55 feet tall.

At mile 47 (and 2hr 21 minutes into the race for me) the El Tour arrives at the Sabino Creek crossing – an event in its self.  Sabino Creek travels through Sabino Canyon which is a deep incision into the southern flank of the Catalina Mountains, and has its headwaters just below Mt. Lemmon, the high point in the mountain range. Sabino Creek is an ephemeral stream, but is usually flowing in the winter months due to the high mountain precipitation.  The average stream flow at the Creek during the tour is usually on the order 10-50 cubic feet per second (a fire hose is about 1-2 cfs).  During last years El Tour the flow reached a few thousand cfs, which meant that the water was calf deep when I waded through – this year the stream flow is more like a garden hose, channel through a culvert. I dismount to run along the dirt crossing and use the porta potty.  There is a Mariachi  Band playing, and scores of volunteers cheering the riders on and refilling rider’s water bottles.  I pause and listen to the music and look at the dry stream boulders at the crossing – and they are fantastic.  You can see large blocks of light colored granite as well as boulders of dark banded gneiss.  The gneiss was created by the strains associated with the detachment faulting 30-20 million years ago; because I am dismounted from my bike I can actually see the geology!


Sabino Creek Crossing – dry in 2014, but still have to dismount. The Mariachi Band was great, and the volunteers here are fabulous.

Once we pass through the Sabino Creek aid station there is about 57 miles to go.  The first stretch of the remaining route is through the Tucson Foothills – a mostly swank and newer group of neighborhoods and resorts located on the Santa Catalina Mountain alluvial fan. After about 60 miles the El Tour turns north on Oracle Road; this is where the change in Tucson since my arrival in 1983 becomes overwhelmingly apparent.  In 1983 there were about 550,000 people in Pima County, mostly residing in the area around Tucson proper.  There were essentially no homes along Oracle Road – even when I rode my first El Tour in 1991 this section of the course was largely rural mesquite chaparral.  Today it is developed and most of this section of the course is through neighborhoods.  By the time I left Tucson in 2003 the population of greater Tucson had grown to about 900,000 and today it is nudging 1.2 million.  As typical of southwestern cities and communities this population growth translates to suburban sprawl; the population of Tucson proper has not grown much, but all the open desert around the Old Pueblo is vanishing.  Given the scarcity of water this population push is unsustainable, but likely to continue.  I suspect that when I return to ride the El Tour in 2026 – I will be 70 year old – the entire ride will be urban/suburban.


When I arrived in Tucson in 1983 the population of the greater Tucson area was a bit more than 550,000. By the time I left it was 880,000 and today it is just a little less than 1.2 million. Most of this population has settle on the fringes of Tucson in places like Oro Valley and Marana — when I rode the tour in 1991 there were no houses along the northern part of the route. Today it is becoming crowded.

Cycling along through the foothills and on to Oro Valley I am now in a group that will be with me until the finish.  We work together — although we are rank amateurs everyone takes a pull, and we maintain a nice pace. I am pretty sure by mile 65 that I am going to easily finish under 6 hours.  I feel very strong, and have been sticking to my fueling and drinking plan. What a difference a year makes!  Last year in the rain this part of the course was littered with riders shivering with hypothermia at the aid stations, but today everyone seems like they are part of a schooled peloton.


The pace line coming down Tangerine Road. I found a group of about 7 that worked together for 20 miles,

After the quick descent from the Tortollita alluvial fan the El Tour course passes under I-10 and does a hard left on to the frontage road along the bank of the Santa Cruz River.  The course is a relatively straight 22 mile shot back to down town Tucson, and a steady, gentle climb.  However, I am tired, and know that this is slog time. It should take me about 1hr and 15 minutes. The real reason it is a slog is is not the gentle uphill but that there is a pretty strong head wind.  However, I am with the same group of riders, and we continue to work together (although slower, as our average pace is more like 17 miles per hour compared to 20 miles per hour earlier in the race).


Vanadinite from the Old Yuma Mine, in the collection of colleague Tony Potucek.

10 miles into the homeward stretch the El tour crosses over a road named El Camino Del Cerro.  If I turned right here I would reach the home I built in the Tucson Mountains.  I was single during the construction and lived in basic camping conditions for the year 1986.  The house was definitely on the outskirts of Tucson at the time (not so much today!), and was located only a short mile from one of the most famous Arizona mineral localities, the Old Yuma Mine. As I noted earlier, the Tucson Mountains are a volcanic complex that once was located above the Santa Catalina Mountains.  That old volcanic complex was moderately mineralized, and the transport along the detachment fault left the mineral riches intact. There are four mines of significance in the Tucson Mountains, and the Old Yuma was the largest and most successful. The Old Yuma was mined for gold, but it also was rich in colorful secondary lead minerals.  It was a favorite locality for collectors that occasionally found seams covered with deep read vanadinite or yellow wulfenite; these specimens now grace mineral collections world wide.  I visited the Old Yuma many times, but never found anything of note.  After I left Tucson the Federal government purchased the mine from my friend Richard Bideaux and cemented the shafts and removed all the mine dumps — it is a locality no more.


The 2014 El Tour de Tucson is in the books.

Finishing the 32nd El Tour de Tucson

5 miles from the finish any pretense of working together with my group falls apart.  Everyone can taste the finish line, and we are at a time of just under 5 hours.  I am peddling comfortably, trying to save a little reservoir for the last mile which can be a sprint.  I round the corner to the last mile before the finish line, and stand to sprint.  However, I seem to have encountered some sort of gravitational well and my bike simply stands still!  I beg my wheels to turn faster, but they don’t.  I cross the line at a clock time of 5 hrs 24 minutes and 20 seconds; the chip time, which takes in account that I did not even reach the start time for over 4 minutes, is 5 hrs, 18 minutes, 56 seconds (this is my garmin time!).  I average 19.5 miles per hour, and am pretty happy for an old guy. The deluge of 2013 suddenly becomes a fond memory!  Michelle, my wife, entered her very first cycling race in this El Tour, riding the 55 mile version of the course.  She finishes in under 3 hrs, and looks fresh like she could have done the 104 miles event.  The furthest that she ever has cycled before the El Tour was 42 miles, so her’s was a fantastic ride.  All told, about 8400 riders participated in El Tour de Tucson — covering difference distances, but all ending together at Armory Park.  The finish line park is a festival, and unlike the finish line of an ultra run, every body type in the human race is represented — and everyone is smiling.


Michelle Hall and Terry Wallace at the finish line with our gold medals!

The 2014 El Tour did not turn out as well for some of my other Los Alamos companions because of tire troubles, but over all, we all feel the disappointment of 2013 vanquished.  I don’t know for sure when I will be back, but the event is one of those “great challenges” that one just needs to experience.  Besides, expending 5500 calories in a race means you are free to indulge in one of Tucson’s iconic restaurants, El Charro and feast on the world’s best carne seca.  Who says bikes, geology and chile don’t mix?

Tales from the Tags: Mineral Labels and Specimen Value

I go down to Speaker’s Corner I’m thunderstruck They got free speech, tourists, police in trucks Two men say they’re Jesus one of them must be wrong – Dire Straits, 1982 song Industrial Disease


Chalcopyrite coating acanthite Joachimstal, Bohemia (now in the Czech Republic).  Originally in the A.F. Holden Collection, bequeathed to the Harvard Mineral Museum, traded out and sold to William Pinch, and eventually came to my collection from dealer Cal Graeber.

One of the questions I get asked most often when I visit a mineral show: “Is it real?”.  I mean this in a mineralogical sense, not a judgement of my personality.  The origin of the question is uncertainty about a mineral sample, and the particular inquiry is focused on whether the mineral is as advertised, or “fake”.  The nature of fakery in the mineral hobby can be subdivided into four broad categories:  (1) is the mineral actually identified correctly, (2)  has the mineral specimen been enhanced, repaired or constructed, (3) is the mineral actually natural, and (4) is the ancillary information with the specimen – locality information, previous ownership, etc. – correct?  To me, the last category is particularly vexing.  The ancillary information, usually provided in a label or series of labels associated with a specimen, documents the history and significance of the specimen. I collect minerals partially because of the their “science” (chemistry, geology, and crystal beauty), but also because they are artifacts of history.  Someone had to mine the specimen, decide it was worth keeping, pass it on to a collector or dealer that valued it, and finally making its way to my collection.  From underground mine to my collection the specimen develops a patina of human history.  I very much value this history —  the story in the label with the mineral is part of its “worth”. The specimen pictured above is an exemplar of a mineral as a historical artifact.  The specimen is a miniature sized matrix acanthite with an epitaxial coating of chalcopyrite. The locality is Joachimsthal, one of the most important historic silver mining regions in the world.  The specimen has a well documented pedigree:  it was in the A.F. Holden collection that was bequeathed to the Harvard Mineral Museum in 1913, and transformed Harvard’s collection from a typical university cabinet into one of the world’s greatest mineral holdings.


Labels for the chalcopyrite coating acanthite specimen pictured at the top of the article. The specimen was in the A.F. Holden collection, went to Harvard, traded to a dealer that sold it William Pinch. Eventually, Pinch sold the piece and it made its way to my collection in the 1990s.

In 1912 the Engineering and Mining Journal declared that the finest collection of minerals in the United States is “believed to be that in the American Musuem of Natural History in New York, the basis of which was the famous Bement collection. There are several important private collections. Among those, that of Col. W.A. Roebling, Trenton, N.J., is considered to be the best; anyway, the largest. Next in rank are probably the collections of A.F. Holden, Cleveland, Ohio and Fred Canfield, Dover, N.J.” Albert F. Holden graduated from Harvard in 1888 with a degree in Mining Engineering. After graduation, Holden entered the family mining business, and by 1906 he had built one of the largest mining and refining companies in the world. His holdings included what would become the Bingham Canyon copper mine in Utah, and dozens of mines spanning the mineral wealth of Alaska to Mexico.  In the 1912-13 Annual Report on Harvard University, the curator of the Mineral Museum, John Wolff, wrote “received this year a mineral collection which represents the greatest single gift of minerals made during its history of one hundred and twenty years…Mr. Holden had found time in the last eighteen years to accumulate one of the finest private collections in existence….As a result, the larger part of the six thousand specimens are of the highest quality, while many are unique.” In the detailed instructions to Harvard accompanying the collection, Holden wrote “There shall be no obligation on the Museum authorities to keep any of the specimens when they have lost their scientific interest”. Although the chalcopyrite coating acanthite in my collection is modest, its tie to a mining great, and subsequent membership in the Harvard Museum, and ultimately its pathway into one of the great modern collectors, Bill Pinch, is what makes it “more” than a pretty mineral.  Remove the labels, and the specimen is interesting, but it loses its significance.  The tale told of specimens from labels is their character — and it is also why labels can also be used to deceive or misrepresent.


Acanthite mounted on a wood pedestal from Bryn Mawr.

The original mineral twitter:  Mineral Labels

I am often surprised that many mineral collectors don’t spend much intellectual capital on the pedigree of the specimens that they pursue and collect.  That statement is, of course, a gross generalization because there are many collectors that intensely focus on the specimen history, but most collectors are first and foremost interested in the perfection of the specimen itself.  However, every specimen has a story to tell, and often that story is gleaned from a few lines written on an old mineral label.  Although labels may only contain the briefest inscriptions, these are often delightful clues to the thoughts and passions of the original collector. The picture above is a large thumbnail of acanthite from the Las Chispas Mine, Arizpe, Mexico.  For a very brief period, the first decade of the 20th century, the Las Chispas mine near Arizpe in Sonora produced some of Mexico’s largest and best specimens of polybasite crystals, large clusters of “poker chip” stephanite crystals, fine acanthite crystal clusters and a few very fine pyrargyrite specimens. Many of the specimens were saved through the enlightened efforts of mine manager Edward L. Dufourcq (1870-1919), and now populate museums and privates collections worldwide.  The pictured specimen is fairly unremarkable, even if distinctive of Las Chispas acanthites.  However, the label (and the wood stand that holds that displays the specimen) are what make this a historical artifact.  I purchased this specimen from a dealer in 1986 – but what I saw when it was displayed in his stock was the label — it is a very distinctive “Vaux” tag! George Vaux (1863-1927) was an attorney and member of one of the most important Pennsylvanian families – in fact, he was the 9th George Vaux (and passed the name on to his son too!). George Vaux was the nephew of William S. Vaux, who one of the earliest American mineral collectors. George followed his uncle’s lead and passionately collected minerals. When he died in 1927 he had amassed an amazing collection, particularly rich in South American and Mexican specimens (Vaux’s Chanarcillo proustites are still considered some of the finest examples of what I believe is the most beautiful mineral). Vaux lived in Bryn Mawr, located west of Philadelphia, and upon his death his family kept the collection intact and on display in their home. Bryn Mawr is home to the small college of the same name, founded by the Religious Society of Friends (Quakers) in 1885. In 1958 the family decided to donate his collection of more than 8,000 specimens to the college – and suddenly a small women’s liberal arts college had a major mineral holding! The transfer of the collection included Vaux’s labels – there are several types, but several thousand were the simple lined cards, with handwritten descriptions (like the one pictured above). In the early 1980s many of the Vaux specimens were traded out of the Bryn Mawr collection, including my acanthite.  The wood stand and black wax mount were Vaux’s work.  On the base of the stand Vaux wrote “Cahn, 11/20” which indicated that he had bought the specimen from Lazard Cahn, a Colorado Spring mineral dealer.  Eventually, it was acquired by Al McGinnis (a San Mateo dealer) for his private collection, which was dispersed upon his death. A few years after I acquired the Arizpe acanthite, I found another Vaux labeled acanthite specimen in the stock of mineral dealer Gene Schlepp.  In fact, the Vaux label was was tagged with the number 703, only a few digits different than the Arizpe piece!


Aguilarite, Guanajuato, Mexico.

The Vaux label stated that the specimen was Argentite (acanthite) from Guanajuato, but I suspected the specimen was actually Aguilarite (Ag4SeS), a far rarer mineral.  The skeletal dodecahedrons are distinctive of the species, and the specimen looked very much like the very best aguilarites I had seen in other collections.  I purchased the piece, and hurried off to the lab to do an x-ray.  My hopes were confirmed – a outstanding aguilarite with history to boot!


Vaux label

The front of the Vaux labels only tells part of the story.  Turn over a Vaux label and there is a few scribbles that connect Vaux to his mineral suppliers.  Below is a picture of the Arizpe and Guanajuato labels.  In Vaux’s hand writing you can see where and when he acquired the specimens.  The Aguilarite was obtained from Wards in 1895 — which is very consistent with the very best samples were mined.  Around 1890, Ponciano Aguilar, superintendent of the San Carlos mine at Guanajato collected an “unknown” that he thought might be Naumannite, and sent it to S.L Penfield for identification — and Penfield discovered it was a new mineral and named it in honor of Aguilar.


Back of the Vaux labels; where the specimen was purchased, when it was purchased, and a three letter code. The code is likely the purchase price.

A mystery on the Vaux labels are the three letters scribbled after the date of purchase.  I have looked at about a dozen Vaux labels and they always have these initials, all different.  Wendell Wilson, editor of the Mineralogical Record, suggested that this might actually be an encrypted purchase price.  Several collectors from the first half of the 20th century used ciphers to record value.  Martin Ehrmann used “tourmaline” as his  cipher — 10, non-repeating letters, each corresponding to a numeral, 1-9 and 0 (e.g.  tne would translate to 190).  Carl Bosch, whose fabulous collection ended up in the Smithsonian Institution, used a similar code, with amblygonit thought to be the cipher used to record value in German Marks.  I don’t have access to nearly enough of the Vaux labels to “break the code”, but it is likely that the three letters are some important secret about the specimens. Not all minerals come with a rich history, and when there is a documented pedigree it is still hard to convert that history to a monetary value.  The Vaux labeled specimens in my collection are cherished by me, but in the future (hopefully distant future) when they are sold to other collectors the value will be mostly determined by comparison of the specimens with “their peers”.  The aguilarite will still be one of the best in the world, with or without the label.  But the real value will be the story behind the minerals – it may not be monetary value, but it will be fingerprints of humanity on stones recovered from the Earth.


Bideauxite, Tiger, Arizona

When Labels Go Bad

One of specimens I treasure the most in my collection is a Bideauxite, a very rare lead-silver chloride (Pb2AgCl3(F, OH)2) from Mammoth-St. Anthony Mine, Tiger, Arizona.  The photograph above is a closeup of my specimen, and displays two hexoctahedral crystals of Bideauxite associated with boleite on a quartz matrix — the crystals are tiny, only a few mm across.  The unusual chemistry of Bideauxite requires a very restrictive set of conditions for formation, and in fact, the mineral is only documented to come from two localities:  Tiger and a small prospect in  Tarapaca, Iquique Province, in northern Chile.  The species is named after the late Richard Bideaux, a good friend and a fountain of knowledge for all things mineralogy (he is co-author of the Handbook of Mineralogy), especially Arizona mineralogy (co-author of Mineralogy of Arizona).  Richard “discovered” the mineral when working on his thesis at Harvard;  he was going through material in the Harvard Mineral Museum from Tiger and found a tiny gray-pink fragments of a mineral he thought was chlorargyrite on boleite.  Richard sent the material to Sid Williams who determined that it was a new mineral, and named it Bideauxite. In 2005, Dave Bunk bought part of the mineral collection that contained many specimens from Erberto Tealdi (the late editor of Rivista Mineralogica Italiana) collection. Tealdi collected a large suite of minerals from Colorado — and in the  material Dave acquired was the most amazingly labeled sample:  Bideauxite, Sherman Tunnel, Leadville, Colorado.  Acquired, Rich Kosnar.  Looking at the sample I immediately knew that it likely Bideauxite, but what a bizarre reference to the Sherman Tunnel!  Never has there been a more ridiculous assertion for a locality — wrong geology, wrong mineralogy, and about as believable as the theory that Roman Christians established a colony on the outskirts of Tucson, Arizona around 700 AD (this theory is based on an archeology hoax, but will live forever on the internet – I love archeological hoaxes!). It is clear that the original label listing the Leadville locality was used to deceive, but really it was a rather flaccid attempt. I eventually obtained the Bideauxite from Dave Bunk, and have labeled it as from “Tiger.” This is an example of a very troubling phenomena in which the Label is Bad.  In the case of the Bideauxite, the bad label has little consequence because  it was so preposterous.  However, for the very reason that labels add to the value of specimens — both in terms of history and monetary value — the issue of bad labels is one of the worst diseases in the mineral collecting hobby.


The Colorado Dragon

Recently, Pala Minerals published an article about the sale of arguably the most important Colorado mineral specimen — a gold sample from the early days of the Colorado’s rich mining history — in their internet newsletter ( The specimen is fabulous – more than 5 ounces of crystallized gold that demands attention.  The specimen is reputed to be from the Gregory Lode, Gregory Gulch, Gilpin County, Colorado – the label is shown below.  The significance of the label is “Gregory” — as in John H. Gregory.  Gregory, a prospector from Georgia, is credited with discovering the first major Colorado gold deposit located near what would become Central City, in May, 1859.  Gregory sold his claims, and pretty much disappeared  (although there are many Gregory legends, mostly they are unsubstantiated canard).  The label changes the “Colorado Dragon” from a great mineral specimen and transforms it to a hugely signifiant historical artifact.  Further, the mineral label states that the gold actually belonged to John Gregory, and that he had personally donated the treasure.  There is absolutely no other evidence that Gregory collected or owned this outstanding gold, nor that he donated specimens, but the label titillates!


Label included with the Colorado Dragon.  Note that it states Gregory donated this gold, even though he disappeared in the early 1860s.

The “original label” for the Colorado Dragon is stated to be from the State Historical Society. The State Historical Society received minerals originally acquired by the Colorado Bureau of Mines over a period of about 80 years, in 1956.  This mineral collection was filled with history – it had specimens from senators, miners, and millionaires.  The label above serves as exculpatory evidence for those that would cast doubt on the provenance of the gold.  The faded piece of paper with a few typed phrases links the nugget with the birth of the Centennial State.


A label accompanying the Colorado Dragon, from the Colorado School of Mines

Eventually, the Historical Society gave the mineral specimens to the Colorado School of Mines, and it was placed into the Mineral Museum holdings.  The photo of the label above is stated to be the School of Mines tag associated with the specimen.  In 1990s the Colorado Dragon was obtained by Colorado Dealer Richard Kosnar (the same Kosnar associated with my bideauxite) from the School of Mines.  This year the specimen was obtained by George Hickox a noted Colorado gold collector. This would be a remarkable tale, but just as the labels add immeasurable value to the gold, they also cast a dark cloud over the authenticity of the specimen.  The problem is that there are at least two more specimens labeled “number 5600” – so three competitors to the throne!  Two of the specimens are labels EXACTLY the same (reference to donation by Gregory, which is certifiably false) including the  Colorado Dragon!  Just as the tag line at the top of the blog from the Dire Straits’ song says that when two people claim to be Jesus, one must be wrong! In the case of the Gregory Gulch gold there are three competitors for the label designated 5600.

CSM 5600 with CSHS label

Number 5600 in the Colorado School of Mines display.  Note no mention of a donation by Gregory.

The photograph above shows a gold specimen on display at the Colorado School of Mines, and it carries the number 5600.  This specimen has all the documentation to suggest that it is the original 5600, although no where is there any indication that it was donated by the original prospector. This does not mean the specimen on display is authentic. There are many reasons that the Colorado School of Mines piece could be a misrepresentation — including an attempt by someone at the School of Mines to cover up trading away the original Colorado Dragon.  But that said, two specimens with the same number, and at least one of those with very questionable historical references? At the very least, one is left with a tremendous sense of uncertainty, and anger that such an important historical artifact is now tarnished. Ed Raines is the Collections Manager at the Colorado School of Mines Geology Museum, and one of the most knowledgeable professionals I know of in terms of Colorado minerals.  Ed is also a bulldog – he pursues information with tremendous tenacity, and is a stickler for facts. He understands the importance of Gregory gold, and has scoured the records to shed light on the mystery.  Along the way he found a third specimen labeled 5600, now in another private Colorado collection!  Two is bad, three is ridiculous.

Lau collection Old 5600

Another 5600! In a private collection

The picture above shows this third specimen, and its label — identical to the one with the Colorado Dragon.  This third specimen was also acquired from Richard Kosnar.  Without labels, all three golds would be interesting specimens;  with the labels they become locked in the evidence room of speculation and innuendo.  Just as labels add to the “value” of many specimens, these simple tags can cast doubt, and ultimately, disgust.  The principals in the original transactions may know the real facts, but today there is only conflicting labels and at best, duplicate specimens.  In my professional life I am asked to make judgments based on incomplete and conflicting data;  I can not conclude anything from this mess other that someone(s) behaved inappropriately.

Why do Collectors Believe?

There are untold numbers of minerals that are inappropriately mated with labels. There are obvious examples where this matching is done with malfeasance – simply mineral fraud. Every collector is also familiar with unintentional mislabeling. This usually occurs when old collections have fallen to a state of disrepair, and labels become disassociated with the physical specimens. There are many tales of collecting apocalypse where carefully nurtured and curated collections that are passed along to uninterested progeny only to end up in a garage sale (I did acquire an outstanding jalpaite thumbnail in estate sale once for the princely sum of 3 dollars!). There are also many labels that are applied to specimens based on “guesses” – some are educated guesses and sometimes they are little more than wishes and hopes (my bideauxite pictured above is now labeled Tiger, but that really is just an educated guess). Unfortunately, once a label is attached to a specimen, however indelicately, it develops some credibility. This credibility resides mostly in the hearts of collectors – it is easy to blame unscrupulous dealers, but in the end it is the collector that decides the value of a specimen. The vast majority of mineral labels are above reproach; if there is something incorrect it is usually based on good intentions (e.g., when I label bideauxite as being from Tiger — no good intention is had by labeling it from Leadville!). However, there are some startling examples where mineral pedigrees that are incredulous, yet are accepted and promoted by knowledgeable collectors. This speaks to the psychology of collectors, especially the most passionate members of the hobby. Their pursuit of minerals can cloud their judgment to point of accepting the flimsiest evidence if it means they acquire something unique.


Barlow Chalcocite: originally sold as Jalpaite

I experienced an example of this power of wishful thinking in the early 1990s when I was asked to write a chapter documenting the silver specimens in John Barlow’s collection. John had acquired an incredible jalpaite, purportedly from the Caribou Mine, located about 20 miles west of the modern city Boulder, from Richard Kosnar. John’s later recollection of the acquisition was that he was skeptical of identification, but when I first saw the specimen in his home in 1993 he presented it as the world’s finest jalpaite – it is pictured above. Peering at the fine miniature, I reacted with typical skepticism and sarcasm – I laughed. I had seen the specimen in the pictured in the Mineralogical Record years before (1976 to be exact), but in person the specimen was stunning….just not jalpaite.  Laughing was probably not the best way to start a serious mineral discussion; nevertheless, John eventually had the specimen “tested” at the Smithsonian, and it was confirmed to be a chalcocite. It was a very fine chalcocite, but clearly was not from the Caribou Mine. John eventually came to terms with Kosnar, and decided that it was a chalcocite from Levant Mine in Cornwall, and had come to Colorado as a collectable by William Turnby, a partner in the Caribou mine back in the 19th century.  Turnby had spent time in Cornwall, thus, this became “a plausible explanation”. This is how the specimen was labeled in John’s collection when he died. Is the Barlow label believable? Not to me.

The most disquieting aspect of this story is that John Barlow was a very knowledgeable collector – why would he accept this fanciful explanation? John was not duped into his belief by an unscrupulous dealer, but truly believed he had an amazing treasure. This tale is hardly unique – many collectors have labels that they want to believe against a preponderance of evidence.

When Specimens are Historical Artifacts, not Works of Art

Mineral collecting has as many different facets as there are collectors. For many, minerals are works of art; for others, they are expressions of science. For some collectors, including me, minerals collections are ultimately an expression of humanity. Labels tell that human story. When labels go awry – intentionally or accidently, the story of a collection is diminished. Sometimes this is inconsequential, but other times, the mislabeling is historical theft.

Tsoodzil: An ultra run on turquoise mountain

How glorious a greeting the sun gives the mountains! John Muir, the great Scottish-American naturalist.


The Summit of Mt Taylor on race day. The view is to the east down the amphitheater.

80 miles west of Albuquerque a lone mountain peak rises above the horizon; it seems distant but significant, an alpine oasis in the high desert of the Colorado Plateau. The peak is Mt. Taylor, an extinct stratavolcano that towers some 5000 feet above the uranium mining boom town of Grants.  The high point of Mt. Taylor is 11,305′, located along the lip of an eroded caldera, and offers unobstructed views for at least 90 miles in all directions of the compass.  The mountain is one of four sacred peaks that surround the Dinetah, the traditional homeland of the Navajo.  The name Mt. Taylor was assigned in 1849 to honor President Zachary Taylor, but the Navajo call the mountain Tsoodzil, and more informally, the turquoise mountain – a name that it deserves as it appears to be a deep blue  gem on the horizon.

Mt Taylor is home to one of the three crown jewels of northern New Mexico trail running (the others being the Jemez Mountain Trail Runs and the La Luz Trail Run).  It is a relatively new event (the inaugural race was in 2012, although early versions of the run existed), but its fame, or at least admiration, has grown rapidly. The start and finish of the Mt Taylor 50k is a couple of miles west of the caldera rim and is at 9400′ elevation.  The course has some steep climbs (and equally steep descents) – about 7000′ elevation gain – much on single track, and through unspoiled mountain top wilderness.  I have wanted to do this race for some time, and signed up for the run within minutes of when the registration was opened in early February of 2014.  The run is limited to 175 people, and indeed, the roster fills early creating a waiting list.

Although I grew up about 100 miles north of Mt. Taylor, I had only visited the peak once; that was back in the summer of 1975 when I was an undergraduate student working summers at Los Alamos National Lab.  We installed a temporary seismic station near La Mosca lookout – which is on the course of the 50k! – to record seismic waveforms from a number of underground nuclear tests conducted in Nevada.  The nuclear weapons tests were part of Project Anvil, a series of 21 tests.  In 1974 the US and Soviet Union agreed to the terms of a bilateral treaty that would limit the size of nuclear weapons tests to 150 kt or less;  this treaty is known as the Threshold Test Ban Treaty (TTBT).  Although the terms of the TTBT were negotiated in 1974, both nations wanted to conduct a series of tests before it would come into force — this resulted in a period of frenzied activity for nuclear testing.  The treaty was submitted to the US Senate (but not acted on) in July 1976, and 150 kt became the punch line in numerous conflicts with the Soviets in the subsequent 15 years.  Little did I know at the time, but the concept of monitoring nuclear tests, and more importantly, determining the nuclear yield from geophysical data would dominate my career.  However, the installation of the seismic station on Mt. Taylor nearly 40 years ago was mostly a just a chance to visit at really interesting mountain top. I was far more familiar with the flanks of the Mt. Taylor were my father and I had collected numerous radioactive mineral species in the early 1970s. The Mt. Taylor 50k provided a long overdue opportunity to visit a wonderful New Mexico mountain.


From the north looking to Mt. Taylor on the horizon above Mesa Chivato, and a volcanic plug called Cabezon in the right center (the picture is high resolution, so click on it).  The picture was taken while touring the geology of the Naciemento Uplift along the western margin of the Jemez Mountains.

Mt Taylor – A beautiful stratavolcano and tombstone

Mt. Taylor is a magnificent landmark – it really is an isolated volcanic peak on the edge of the Colorado Plateau, a huge region (more than 130,000 square miles) of relatively flat mesas and valleys with an average elevation of about 7000′.  The Plateau is a geologic mystery; it represents a region of relative geologic stability that has existed for  nearly a half a billion years.  All around the plateau there are geologic provinces that suffered tremendous episodes of geologic deformation – the Rocky Mountains, the Basin and Range in Arizona and Nevada, and the Rio Grande rift in New Mexico.  Why did the Colorado Plateau escape these tectonic spasms?


Location map from Kelley 2014; The Mt. Taylor volcanic field is part of a series of volcanic provinces that ring the southern half of the Colorado Plateau. Mt. Taylor sits atop Mesa Chivato, which is a group of basaltic volcanic vents that were most active as Mt. Taylor became extinct.

Mt. Taylor seems unique, but is actually part of a much larger geologic phenomena – a ring of volcanoes that surrounds the southern boundary of the Colorado Plateau.  The most famous of these mountains in this “ring of fire” is the San Francisco Peaks north of Flagstaff. The Plateau is defined by a thick sequence of sedimentary rocks – some of these rocks were deposited in marine environments, others in wide river valley flood plains, and still others represent long periods of time when the surface was covered with wind blown dunes. Taken together, this block of real estate was near sea level for nearly an eighth of the entire age of the Earth. Around 25 million years ago the Plateau began to rise uniformly to its present elevation of 7000’ feet. The cause of this rise is a subject of much speculation and research, but most geoscientists accept that the uplift was due to a hot mantle. This idea holds the key to why the edge of the plateau has so much volcanism, similar to that that that produced Mt. Taylor. The juxtaposition of the thick, and obviously stable, lithosphere of the plateau and the much thinner lithosphere of the Basin and Range created what is know as Edge Driven Convection (EDC). This EDC brought hot mantle materials up toward the surface along the edges of the plateau and it melted rocks both in the upper mantle and lower crust which then erupted in a series of volcanoes.  The same reason Los Alamos has the marvelous Jemez Mountains is the reason Grants celebrates the glorious vista of Mt. Taylor.


A notional cross-section through Mt. Taylor – the conical shape of the stratavolcano is a layered stack of andesites and ashes from eruptions. At some point Mt. Taylor probably reached 14 or 15,000 feet elevation; however, the volcano eventually blew its top and created the geomorphology that is seen today.

Mt Taylor first erupted about 3.5 million years ago, and was active for 2 million years.  The volcano had many eruptions that were mainly ash; these eruptions built an edifice that probably reached a maximum elevation of between 14 and 15,000 feet (which would have made the Mt. Taylor 50k much more difficult!).  Today there is a pronounced depression at the top — it is called the amphitheater — that is the eroded remains of a caldera.  The amphitheater is open towards the southeast and is drained by Water Canyon.  The shape of the amphitheater looks eerily like Mt. St. Helens 30 years after that volcano blew its top. As the volcanism of Mt. Taylor was winding down, a whole series of small vents developed to the northwest.  These vents extruded basalt rather than ash, and built a broad and flat table land known as Mesa Chivato.


Aerial view of Mt Taylor and Mesa Chivato. The high crest of Mt Taylor is visible in the new snowfall (the snow line is about 7000′ in this photo). The right of the crest is the amphitheater which drains to the southeast. The broad basaltic table land that is Mesa Chivato is to the upper right of Mt. Taylor (photo from Kirt Kempter) .

As spectacular as Mt. Taylor is, the rocks of the Colorado Plateau that sit beneath the volcano are more unique. There is a 2 km thick sequence of sedimentary rocks hidden below Mt. Taylor and Mesa Chivato, and these rocks contain one of the largest known reserves of uranium ore in the world. This uranium fueled the American nuclear power and nuclear weapons enterprises for half a century; it also brought tremendous devastation to the miners, in particular the Navajo miners, that extracted the ore from underground workings.

The long history of stability of the Colorado Plateau played an important role in making it a “trap” for uranium.  As great mountains of granite and ancient volcanoes rose and were eroded over the last half a billion years the rocks from these massifs were ground to cobbles and grains.  In turn, these grains slowly released their constitute minerals which reacted with the environment;  a tiny fraction of these minerals contained uranium, which was eventually mobilized by the ground waters and flowed through the rocks of the Plateau.  Occasionally these ground waters would encounter conditions that caused the uranium to precipitate out of solution and be deposited as new minerals.  When these conditions lasted millions of years the precipitates would become extensive enough to become uranium ore.  After WWII the US government started a prospecting frenzy for uranium, and the sediments of the Colorado Plateau became site of a new “gold rush”.


Location map for uranium mines that have produced ore to be milled. 98% of the ore came from mines in New Mexico, Arizona, Colorado and Utah – all on the Colorado Plateau.

Uranium was first discovered in New Mexico part of the Colorado Plateau in 1950.  A Navajo shepherd, Paddy Martinez, had heard about the uranium rush, and seen some yellow colored ore.  Martinez recalled seeing rocks with similar yellows stains at Haystack Butte, just west of Grants (strictly speaking, Martinez “rediscovered” the uranium deposits that others had noted in passing in the early 1920s), and started a mad era of exploration and mine development in the Grants Mineral Belt, which encircles Mt. Taylor. Legend has it that Martinez brought several pieces of yellow ore to stake his claim, and that the yellow ore was carnotite. I personally doubt this is true because carnotite is extremely rare in the grants Mineral Belt (I have never seen a single specimen). Nevertheless, the population of Grants went from a few thousand to 45,000 in a decade.  Two major mines were developed; Ambrosia Lake, north and west of Grants (you can see the mine workings as you drive up to the start of the Mt Taylor 50k), and the Jackpile Mine, a few miles east of Grants.  The Jackpile mine was remarkable; it was discovered in 1951, and between 1956 and 1960 it was the largest producer of uranium in the world – during the same time it produced more uranium than all other mines in the US combined!


Jackpile uranium mine in full production in the 1970s.  Mt Taylor is visible on the horizon of the picture.

The ore of the Jackpile mine is dispersed uranium — mostly in the form of the minerals uraninite (UO2) and coffinite (U(SiO4)1-x(OH)4x) — in a sandstone that was created by a systems of braided streams that flowed from somewhere west and south of present day Grants in Jurassic time (145 to 200 million years before the present).  The host sandstone at the Jackpile defines a sausage shaped body that is about 50 km long and 25 km wide, and the average grade of ore is less than one percent.  However, it is clear that one of the factors that contributed to the deposition of uranium out of the ground waters was the presence of carbonaceous materials — dead plants.  Throughout the Jackpile sandstone there are large petrified logs – trees that must have been swept away in floods and then stranded as log jams – and these petrified logs are where uranium concentrations can rise to 20 percent or more.  In 1972 my father got a call to visit the Jackpile because they had discovered a cluster of logs that appeared to be completely replaced by uraninite.  I accompanied my father, and we collected about 20 pieces of petrified wood.  From our geiger counters it was clear that the material was radioactively “hot”, but the uniform dark color made identifying the minerals by sight impossible.  One of these logs became the source materials for my education in power diffraction. Back in Los Alamos we prepared about 15 different powder samples and my father performed the x-ray diffraction at work; he then brought home the films and it was my job to identify the diffraction peaks.  The material ended up being almost all coffinite.  I have long since gotten rid of all the material (safely and securely), but I learned how to identify minerals with x-rays on uranium grunge….sort of poetic justice I suppose.


The decay chain of uranium 238 to radon and progeny. Although U238 is barely radioactive, its daughter radon 222 and subsequent decay to polonium 210 are cause of many miner’s lung cancer.

The Jackpile mine was an open pit mine, but many of the other mines had underground tunnels.  In general, the ventilation in these underground facilities was poor, and the presence of the uranium means that there was radon, which is a radioactive decay product. U238 is marginally radioactive (it has a half life roughly equal to the age of the Earth!), but when it does decay it will eventually produce radon gas as a daughter.  This gas is quite radioactive and decays by emitting an alpha particle.  The progeny of radon, in particular polonium, also emits an alpha particle.  Inhalation of radon allows the alpha particle emissions to interact with the very sensitive tissues of the lungs;  this irritation of the lung tissue dramatically increases the chances of developing lung cancer.  The cancer rates among Navajo uranium miners is extraordinary, and a very sad legacy of the mad rush to find the heavy metal.  A mineralogical sidebar to this tale is that in the year 1530, Paracelsus described a wasting disease that afflicted miners in Joachimsthal which he called male metallorum – we now know that is lung cancer from the exposure to radon.

The Navajo also associate Mt. Taylor with the home of the chief of the monsters – and by monsters, the Navajo means those things that get in the way of a successful like.  The monster the Navajo deal with now is leetso, the yellow dirt.  It is strange to write about running an ultra race and spend so many words on things nuclear.  But to me, there is always a celebration of the place of the race, and for Mt. Taylor there is a fabric that is very much woven by things nuclear;  a high peak overlooking a legacy, a cenotaph.


Start of the race at 6:30 am. Cool and dark.

The race

I signed up for the Mt. Taylor 50k in February, and had every intention that it would be the my crowning achievement for ultra runs this year.  However, my approach to the race was quixotic at best.  I have run 4 ultras, many shorter trail run races, climbed Rainier, and done several cycling events this year, and by the end of September, my dedication to training for a long tail run had wained.  As September 27 approached I oscillated between unrealistic optimism and trepidation.  My base fitness was good – I run 30 to 35 miles per week and cycle 60 to 65.  However, I had not put in the long miles on individual runs that I needed for a tough ultra.  Further, much of the summer I had chosen to train for climbing Rainier (carrying a back pack, hiking 14ers in Colorado). In fact, I was still experiencing the effects of Rainier — I still had some blisters on my feet, and I had only partially recovered from an infection I got from stabbing myself in the leg with a crampon.  Finally, I had been called unexpectedly to DC the week before the 50k run for a very tough set of meetings and only flew back to Albuquerque late in the afternoon before the race.  But, then again, what could go wrong in 50 kilometers?


The race ascends the ridge below MLookout as the sun is rising. The color of fall is glorious. View to the west.

The race starts at 6:30 am – in the dark at Rock Tank Shelter.  The runners head due east and climb about 1500′ over 3.5 miles to the ridge just below the Mosca Lookout.  The goal is to reach the ridge as the sun rises above the horizon and welcomes Mt. Taylor to a new day.  I am quite certain that many of the runners made the ridge as the sun rose — I settled for a little more leisurely ascent, but nevertheless basked in glow of autumn colors and fantastic views.


My gps track through the Mt. Taylor 50k.

The course for the Mt. Taylor race has three major climbs;  the Mosca Lookout ridge, the top of Mt. Taylor, and then a tough final climb up out of Water Canyon in the Amphitheater. After the first big climb the trail is descends down a forest road to about mile 10.5  This descent is fast and should be pretty easy.  Lots of people pass me running fast.  However, I realize that something is amiss on the descent.  My toes are really hurting because of the blisters, and the downhill pounding irritates the wounds.  I am a little unsure if my feet will betray me, or this will pass like the many aches and pains that appear during a 50k race.  Around the 11 mile mark the course turns on to the Continental Divide Trail (CDT).  This trail is soft single track, and rolling through conifer forest.  It is just a pleasure to be running along the trail and thinking about the fact that you could actually follow this trail from Canada to Mexico, some 3100 miles , and straddle the drainage divide between the Pacific and Atlantic.  No one is passing me on this section of the trail, but it hindsight that is because there is no one behind me.

The CTD loops around to return to the Rock Tank Shelter at about mile 16.  My feet are really bothering me as I approach the aid station, and I seriously consider dropping out here.  However, the race organizers have hung a banner that basically paraphrases the famous Lance Armstrong quote: “Pain is temporary. It may last a minute, or an hour, or a day, or a year, but eventually it will subside and something else will take its place. If I quit, however, it lasts forever.”  What, seriously?  Like the Sword of Damocles, the quote on quitting hangs over me.  I stumble into the aid station, get my drop bag, take off my shoes, change the bandages, and continue the journey.


The long trail up to the summit of Mt. Taylor

The run between Rock Shelter and Gooseberry aid station is pretty flat and easy.  I am slow, but I am also determined to finish now.  Of course, I am beginning to fret about actually making the cut off times at the various aid stations!  The Gooseberry aid station is at about mile 20, and the many volunteers admonish the runners to be prepared for the long climb to the top of Mt. Taylor.  Indeed the climb is unrelenting for 2000 feet over the next 3.25 miles.  I did not find the climb to be physically punishing, but it was a mental challenge.  After about 2 miles the trail emerges from tree cover and you can see the top of the mountain;  but as one gazes towards the goal you can see switch backs and tiny dots representing runners ahead of you that appear to be barely moving.


The elevation profile — three climbs, but the climb from Gooseberry aid station to the top of Mt. Taylor is epic.

I actually began to pass people on the ascent to Mt. Taylor.  Most of the runners (I use the words “runner” here out of respect.  None of us are running up this climb) look pretty bad to me.  Sweating, cursing, and asking the rhetorical question of “are we there yet?”.  I suppose I looked the same, but in my mind I had to look better than that.  The geology of the whole run is pretty uniform.  The rocks are andesite – gray and sharp.  However, on the ascent you begin to get views into the amphitheater, and magnitude of the stratavolcano comes into focus.  On the far horizons you can see the pastels of the rocks of the Colorado Plateau, and even some of the volcanic plugs dotting Mesa Chivato.


Andesite ridge in the amphitheater — monument to eruptions past.

The last few switchbacks brings you to the summit ridge.  I can see the Jemez Mountains to the north and my home.  I can see the Ladron Mountains to the south (just north of Socorro), and I can image that this very vista has invoked the same sense of wonder I have right now for 5 thousand years.  Many others have come here before me, and I hope my son and grand children will follow.

Mt Taylor 50k - September 27, 2014

Finally at the top – it is cloudy, and threatening rain. However, it just brings relief from a warm September sun.

At the summit I am surprised to see my wife Michelle who has been waiting patiently for me for 90 minutes.  She has hiked up to take pictures, and seeing her provided a jolt of energy I needed to finish the race. The official photographer is also at the summit, and he deflates me as fast as seeing Michelle lifted me — he asks “is there anyone behind you?”.  I want to say, “oh yeah, there are lots of slower people than me, and I will not experience the pain of quitting!”.  But alas, I mumble that there are several people yet to come.  From the summit there is a tricky descent into the aid station at mile 24.  At this aid station the diabolical streak of the race organizers surfaces.  The course descends nearly 1000 feet into the amphitheater over 2 miles only to reverse course, and climb back up those same contours fighting gravity for 1 1/2 miles back to the same aid station.


Running downhill towards the finish line.  Almost done!

I comtemplate the sadistic streak in the race organizers, but any homicidal thoughts are quickly tempered by the truly outstanding volunteers that work on the course.  They are among the best I have ever seen, and their kind words of encouragement and concern for the runners is amazing.  There are now only a few miles remaining, mostly down hill, to the course finish.  My feet feel pretty much like hamburger, but the end is in sight.  I begin the descent – but wait, all those people I passed coming up the big hill start to pass me!  They all say “great job” – I can’t believe I am actually being passed by those folks that looked terrible below the Mt. Taylor summit.  They don’t look terrible now.  I amble into the finish line a little dejected, but happy that I committed to doing the entire course.  I feel I have some unfinished business, and will have to return next year to run the race the “right way”.


It is a pleasure to remove my shoes – my feet are not a pretty sight, but the Mt. Taylor medal is terrific.

The great volunteers at the finish line have food, and make you feel like you must be in first place.  That notion is quickly dispelled when you notice that your drop bag is quite lonely on the trap where there were 175 drop bags a few hours ago.  However, I am informed I won a door prize, and it is a Patagonia jacket!  I have never won any prize for running before, and even if the trophy is purely based on serendipity, I feel like a winner!  It took me 8 hrs and 50 minutes, by far my worst ultra.  But I am quite glad I did it.  When I take off my shoes a survey the damage, I decide that I will not be running for a couple of weeks.  I have to get these toes back into functional form.  Within a couple of hours of the race conclusion all the pain has faded, and only the joy of the journey lingers.  I loved the Mt. Taylor 50k.

Climbing the Great White Whale: Mt. Rainier and marveling plate tectonics

Each volcano is an independent machine—nay, each vent and monticule is for the time being engaged in its own peculiar business, cooking as it were its special dish, which in due time is to be separately served – Clarence Dutton, American Pioneering Geologist, 1880.


Mt. Rainier, the great white mountain (for me, the great white whale!). This photo was taken on Sept. 9, as I flew into Seattle to begin my journey to the summit. The photo is from the east/north, and you can see the summit crater on the top left flank of the mountain. The clouds are at about 6500 feet elevation.

Mt. Rainier is the most iconic mountain in the contiguous United States. Its nearly perfect conic shape rising 14,410 feet above sea level, and located only 35 miles from Tacoma and Puget Sound make it the most prominent geologic structure in the country; the white cap of the summit plays a game of hide-and-seek with the major metropolitan sprawl of Seattle-Tacoma and when the clouds rise even the most jaded Emerald City resident is jarred by its majesty. I have long wanted to climb Rainier, but never found the opportunity in my youth or the time in my middle age. However, my wife surprised me with a gift on our 25th anniversary in 2013 – the opportunity to climb the great white whale. Work commitments still made the scheduling of the climb non-trivial, but finally in September of 2014 I had the chance to join an organized expedition.


Mt Rainier from an airplane flight (SEA-DFW) I took in the summer of 2013. The clouds cover the summit, which has a topographic prominence of over 13,200 ft. There are 26 alpine glaciers on Rainier which gives it its perennial white appearance.

Rainier has a special place in the minds of geologists – it is a magnificant monument to the violence of plate tectonics. The Cascade Mountain Range stretches from Mt Garibaldi located just north of the Canadian-American border to the Lassen Peak in northern California. Along the 700 mile arc of the Cascade Mountains there are at least 20 young volcanic peaks – Rainier is the highest today, although the nature of stratovolcanoes is that Rainier will eventually follow the example of Mt. St. Helens and “blow its top”. In the 1960s it was recognized that the Cascades where the volcanic signature of a subduction zone – the collision between the Juan de Fuca oceanic plate to the west and the North American continental plate to the east. I was a graduate student at Caltech in the late 1970s, and understanding the nature of subduction was a subject of intense research. In addition to stratovolcanoes, subduction zones are the source of most of the largest earthquakes observed on the planet. Understanding why some subduction zones had mega earthquakes – events with magnitudes that exceed 9.0 – while others only had earthquakes with a maximum magnitude of 8 or 7 was a mystery. In the Seismolab at Caltech there was a daily coffee in which the faculty and other graduate students discussed the most recent seismicity and new areas of research. It was in these “coffees” that a generation of seismologists were created – everyone was expected to contribute to the discussion and debate, and very foundations of modern seismology were laid. Hiroo Kanamori, perhaps the greatest observational seismologist in history, was pondering the “why some subduction zones have mega earthquakes” question and working with  several of my peers developed the rationale for mega thrusts based on the concept of “coupling” between the subducting plates. This spawned the concept of “comparative subductology” which is rooted in Scottish geologist James Hutton’s concept of uniformatarism – if it is happening now, then it happened in the past, and will happen in the future. One of the surprises of the comparisons of subduction zones world-wide was that Cascadia looked a lot like the segments of the Chilean and Aleutian subduction zones that generated mega earthquakes in 1960 and 1964. However, Cascadian was pretty quiet seismically, so there was a general skepticism in the geologic community that Seattle would some day have an earthquake that would dwarf anything that could happen in California. Today the discussion is not about size of a future earthquake in Cascadia, but rather when and how often.


Caltech 1980 — I am one of the leaders of a field trip to Owens Valley (I am the guy at the far left with the clip board and the really strange ball cap) after the Mammoth Lakes earthquake sequence. The earthquakes occurred within a week of the eruption of Mt. St. Helens, leading many to suggest a link. The Seismolab was home to an amazing cadre of faculty and graduate students in the 70s and 80s that help define the paradigm of modern plate tectonics — including the understanding of the Cascadia subduction zone.

My own research at Caltech was more focused on computational methods for seismology and understanding the seismograms from nuclear explosions – however,  I was captivated by the discussions of mega-thrusts. In May 1980 Mt St. Helens erupted – and the reality of the restlessness of Cascadia hit home. I very much wanted to climb Mt. Rainier right then. However, it took nearly 35 years before the opportunity would arise. Of course, this is a geologic blink (or wink!) of an eye, and the decades had not diminished my enthusiasm to walk on the volcano.


Google Earth image of the Cascades. The white dot in the middle is Mt. Rainier. To the south (to the left in the image) are Mt. Adams and Mt. Hood. This line of high peaks are stratovolcanoes above the subducting Juan de Fuca oceanic plate. The high mountains of the Cascades blocks the oceanic moisture and makes the Pacific Northwest coastal region a rain forest — and a relatively dry desert in eastern Washington and Oregon.

A brief history of Mt. Rainier (apologies to Stephan Hawking)

Most discussions that start with the topic of “history of Mt. Rainier” focus on it relatively modest relationship between the mountain and man. The earliest evidence of human occupation of the Pacific Northwest is about 13,000 years before the present, and it is certain that the mystic vision of the rugged, glacier -covered tower of andesite evoked the same since of wonder that it does today.

The first written records associated with Mt. Rainier are from the annals of Captain George Vancouver who was the commander of the English vessel Discovery that was sent to explore the Pacific Northwest. In May of 1792 the Discovery sailed into Puget Sound, and Vancouver saw the snow covered volcanoes of the Cascades, and noted three (Mt. Baker, Hood and Rainier) stood out “Like giants stand To sentinel enchanted land”. On May 8, Vancouver wrote “the round snowy mountain, now forming its southern extremity, and which, after my friend Rear Admiral Rainier, I distinguished by the name of Mount Rainier”.


The eruptive history of the Cascade volcanoes (figure from the Pacific Northwest Seismic Network) over the last 4000 years. Mt. Rainier is the largest of volcanoes, but it the last few thousand years it has been less active than Mt. St. Helens.

The eruption history of the Cascades – about 50 eruptions in the last millennium – doubtlessly meant that the indigenous peoples knew that the Cascade peaks were volcanoes. However, this first recorded suggestion that Rainier was volcanic was noted in the diary of William Fraser Tolmie in 1833. Tolmie was a remarkable naturalist from Scotland that was trained as a physician at Glasgow University, and joined the Hudson’s Bay Company in 1832. Upon arrive in Puget Sound one of the first tasks he undertook was to visit Rainier on a “botanizing excursion”. In is notes he wrote that the rocks of Rainier were “volcanic”. I don’t know what character of the rocks lead him to that conclusion, but Tolmie set the stage for USGS studies 40 years later that would confirm that Rainier was a composite volcano. As a side note, Dr. Tolmie as also the first person to write about an earthquake in Cascadia when a small tremor struck Puget Sound on June 29, 1833.

Mt. Rainier attracted many attempts to scale its heights, but the first documented successful ascent occurred by the son of the first governor of the Washington Territory and a pioneering mountaineer in 1870. General Hazard Stevens (a well-named military man, especially climbing Mt. Rainier) first came to the Puget Sound area with his father in 1854 and resolved to climb the “great white mountain”. After a military career and the end of the Civil War, Stevens returned to Washington Territory, and teamed with Philemon Beecher Van Trump in August 1870 to climb Rainier. Stevens wrote an account of their journey – which was quite harrowing – that was published in Atlantic Monthly in 1876. Stevens wrote “We had spent eleven hours of unremitted toil in making the ascent, and, thoroughly fatigued, and chilled by the cold, bitter gale, we saw ourselves obliged to pass the night on the summit without shelter or food, except our meagre lunch. It would have been impossible to descend the mountain before nightfall, and sure destruction to attempt it in darkness… Climbing over a rocky ridge which crowns the summit, we found ourselves within a circular crater two hundred yards in diameter, filled with a solid bed of snow, and inclosed with a rim of rocks projecting above the snow all around. As we were crossing the crater on the snow, Van Trump detected the odor of sulphur, and the next instant numerous jets of steam and smoke were observed issuing from the crevices of the rocks which formed the rim on the northern side. Never was a discovery more welcome!” Today we recognize that they had found fumarole activity, a reminder that silhouette of Rainier is only temporary.


The Muir party summiting Mt. Rainier in 1888.

P.B. Van Trump would visit the summit 5 more times including guiding John Muir in 1888.  Muir had to be convinced to undertake the climb, but once at the top he stated “I hardly know whether I had better try to describe the view but will say that for the first time I could see that the world was round, and I was up on a very high place. The air was very light…I stood there all alone, everything below and all so grand. I had never before had such a feeling of littleness as when I stood there and I would have stood there drinking in that grand sight, but they wanted to go so we started down”.

By the 1930s geologists had begun to unravel the complex volcanic history of Mt. Rainier. The present conically shaped mountain is quite young – less than 600,000 years old. Beneath the high reaches of the mountain though are a complex series of mostly volcanic rocks that record ancient geologic environment and long extinct versions of Mt. Rainier.  The most prominent basement rock is the granodiorite of the Tatoosh Pluton (there are a range of ages for the pluton which probably reflects a complex history – it cooled between 25 and 12 million years before present) which was the crustal magma chamber of former stratovolcanoes.


A geologic cross-section through Mt. Rainier from Crandall (1969). The modern andesite and mudflows that define Rainier today lie above a large granodiorite batholith that is approximately 25 million years old.

Mt. Rainier birth as a stratovolcano probably occurred about 850,000 years before the present, and the bulk of the present conical shape is about a half of a million years old. The present summit has two craters that reflect recent eruptions.  It is clear that in the past the summit of Rainier was somewhat higher — maybe reaching 16,000 feet elevation — but explosive eruptions have removed the older cap rock.

Although the nature of the Cascades and Mt Rainier were understood by the 1960s, it took the articulation of theory of plate tectonics to set the framework for why the stratovolcanoes exist. The North American plate, dominated by a large continental mass has interacted with an adjacent oceanic plate, known as the Farallon Plate, since Jurassic time (more than 150 million years before the present). Eventually most of the Farallon plate was subducted beneath North America, but a fragment remains off the coast of Washington, Oregon and northern most California. This fragment is known as the Juan de Fuca plate, and is being subducted at a rate of about 4 cm/yr.  In addition that subducted oceanic crust is young – about 10 million years old.  The USGS figure below shows a notional cross section beneath Washington.


The Cascade volcanoes are a direct product of the subduction of the oceanic crust of the Juan de Fuca Plate.  As the plate descends beneath North America the minerals within the plate release water due to increasing pressures and temperature in the mantle.  This water has the effect of promoting melting of mantle rocks in North American kneel above the sub ducting plate.  The melt rises, and eventually creates magma bodies in the lower crust, which in turn occasionally erupt in volcanoes at the surface.  Once a pathway for the magma to rise to the surface is established a stratovolcano grows. A science paper that was published this year (2014) provided an image of the mantle and crustal rocks beneath Mt. Rainier.


Electrical resistivity in the Earth for a cross section beneath Mt. Rainier (the location is shown with a triangle).

The electrical resistivity of rocks is highly dependent on a couple of things;  temperature, water content, and mineral content.  In the figure you can see the cold oceanic crust of the Juan de Fuca plate descending (the blue streak on the left side of the figure).  At about 50 km depth pressures are reached that cause a “de-watering” of the plate, which in turn, promotes the mantle melting.  This is the red and yellow colors beneath Mt. Rainier. The dark red blob to the left of Rainier is likely it’s magma chamber, located between 5 and 10 km below the surface.

Although the volcanoes of Cascadia are not at all unexpected, seismologists did not understand why earthquakes seemed so infrequent in Washington.  Most subduction zones would have a much higher rate of seismicity that was observed here  — and this was the topic of discussion at Caltech in the late 1970s.  Kanamori and graduate student Larry Ruff looked at subduction zones worldwide and plotted the size of the maximum observed earthquake as a function of the age of subducting plate and the rate at which the subduction was taking place.  The analysis showed that rapid subduction of young oceanic plates resulted in very large earthquakes — mega thrusts.


Size of maximum observed earthquake as a function of rate of subduction and age of plate being subducted (from Ruff and Kanamori, 1980).

Tom Heaton and Kanamori used this “comparative subductology” and other geophysical constraints to postulate that the Cascadia subduction zone was capable of generating a mega-thrust earthquake — as large as magnitude 9.0 (paper appeared in 1984). The paper was meet with a great deal of skepticism because the seismicity along the Oregon-Washington coast was quite moderate.  However, in 1987 Brian Atwater, a USGS geologist, found evidence of a major tsunami inland from the coast.  Finally, Japanese seismologists had long been perplexed by a tsunami that hit the coast of Japan in 1700 but did not appear to be connected to any Japanese earthquake.  Connecting the dots, seismologists were able to show that the 1700 Japanese tsunami was most likely created by an earthquake with a magnitude between 8 3/4 and 9 1/4 in Cascadia.


A trench through a coastal deposit in Oregon shows the sands brought ashore by the 1700 tsunami (Atwater et al., 1999).

Today there remains debate about the repeat frequency and size  expected for the Cascadia earthquake, but it is now excepted that it is only a matter of time before it strikes.  Mt Rainier seems like an ancient and noble giant benignly guarding Puget Sound. In fact, it is a very ephemeral geologic feature that will disappear in a few hundred thousand years, and most certainly will do violence to the equally temporary residents of the Pacific Northwest.  Surely this makes climbing Rainier most interesting for a geoscientist!


Mt. Rainier from Paradise Ranger Station. This is the start of the IMG hike up the mountain – elevation of Paradise is at an elevation of 5200 ft, snow line is 7000 ft, and the top is 14,411 feet.

The expedition

The National Park Service keeps track of the number of people that attempt to climb Mt. Rainier and those that actually make the summit.  The numbers are a little surprising;  a little more than 10,000 attempt the ascent annually, and about half actually make it tothe top.  This statistic is pretty robust for the last 25 years, and clearly establishes Mt. Rainier as a signifiant challenge.  It is difficult to obtain quality data on the reasons that the success rate is so low, but the two most common anecdotes are weather and altitude maladies.  The weather is easy to understand – the strong oceanic flow from the Pacific brings significant moisture inland to the mountain. When the flow encounters the mountain it is forced to flow over the elevation – which cools the air, which in turn forcing out the moisture, building clouds, and raining/snowing. The jump off for my expedition is the Paradise Ranger Station (elevation 5,200 feet), which has an annual rainfall of 126 inches. That is twice as much precipitation that is received at Ashford (elevation 1,760 feet) the home to International Mountain Guides, my chosen expedition team. Ashford is only a few miles west of Paradise, but the difference in rainfall illustrates the rapid change in weather and how the steep topography of Rainier controls its environment.

The challenge of the weather, and the fact that a significant stretch of the ascent is on ice are the reason that I chose to join an expedition rather that trying to cajole a few friends (whom are all as old as I am) to take a week off work and avoid ice crevices.  I was not particularly worried about the physical part of the climb – running ultra trail races is more demanding – but I last climbed alpine glaciers more than 25 years ago, and as Shakespeare said “The better part of Valour, is Discretion”.  There are three well regarded companies that provide a suite of guided expeditions up Mt. Rainier.  I choose International Mountain Guides (IMG) for my adventure based on the rave review of a friend.  I was a little nervous about joining a group expedition – in general, I am not a group kind of guy – but my friend assumed me that this was a great experience, and in fact, he was correct!

On Wednesday afternoon (Sept. 10) the 8 climbers in my expedition checked in with IMG in the small town of Ashford which is situated on the Nisqually River.  The Nisqually is the main drainage of the southern half of Mt. Rainier, and I spent a couple of hours before checking in at IMG facility hiking along the river, and there are some spectacular exposures of the Paradise Lahar cut by the river channel.  The age of the Paradise Lahar is probably about 7,500 years before the present, and the thickness exposed near Ashford is at least 100 feet — it must have been a significant and destructive event.  The purpose of checkin is to assure that all the hikers are ready (so there is a very long equipment check), make introductions, and set expectations.  The climbers in my group come from all walks of life; the director of strategy for a unit from a major company, a nurse, commodity trader, dentist, venture capitalist, lawyer and a financial analysts for an aerospace company.  All have experience in mountains, although highly varied.  Most importantly, all seem like fine people to send the next three days with tied to ropes, sleeping in crowed tents, and cursing crampons.


IMG delivers the expedition to Paradise. The wind is very strong, and the posted wind chill is 38 degrees.

The expedition started on Thursday morning — loaded up out packs at IMG headquarters and traveled east up the Nisqually River to the Paradise Visitor Center.  I had weighed my pack early in the morning – full water bottles and mountaineering boots attached, and it was a marginally agreeable 46 pounds.  But, alas, I forgot I had to take a group food package that would eventually become my dinner and breakfast the next two days.  I don’t know how much my package weighed, but probably on the order of 5 pounds.  So, loaded pack was about 50 pounds, about 45 pounds more than I ever run with on the trail.  This was the only thing that I was truly dreading;  pre hip and knee replacement 50 pounds would be no problem, but not positive what the next 3 days would hold.

Although the morning felt cool at Ashford, it was down right cold at Paradise.  The wind was blowing strongly, and the posted wind chill was 38 F.  IMG assigns 1 guide for every 2 climbers, so our team was 12 strong.  Our lead guide was Cedric Gamble, and had the job of both assessing risk and assuring the team that were are super strong climbers; thus, we heard both the comment that the wind was amazing and not at all usual, and surely this weather will pass and all is good.  I had my Garmin GPS watch and tracked the multi day climb.  By my watch, the starting elevation was about 5100 feet. The path wanders out of Paradise and climbs up to Pebble Creek (this was about 3 miles by the route we were on, and a gain in elevation of 1900 feet).  Hiking is easy even with the full pack, although the wind gust literally blew me over a couple of times.


Climbing the Muir Snow Field – putting on our mountaineering boots.  The views to the south are spectacular with Mount Adams, St. Helens and Hood dominating the horizon.

Crossing Pebble Creek, the trail runs into the Muir Snowfield.  The snowfield is not a glacier but a perennial mass of snow that is both slick and wet.  The path for our expedition is to follow the snowfield up to Camp Muir, some 2.2 miles and 3000 feet elevation gain away.  We changed out of our trail shoes into mountaineering boots for the trek up to Muir — this meant that my pack was lighter, but it also meant that I had to wear the plastic mountaineering boots, which are  composed of an outer hard plastic waterproof shell and an insulating inner boot. These are heavy and warm, and I absolutely hate them.  Too heavy and hot, it was like running in dress shoes.  Over the next couple of days I would realize that these boots, when outfitted with crampons, where by far the most difficult aspect of the entire expedition.


IMG tent at camp Muir – a great restaurant.

About half way up the Muir snowfield we ran into another IMG team descending the mountain.  A rather sobering and somber conversation took place between the two teams — the descending team had not been able to summit because of the high winds and had turned around at 13,000 ft elevation.  It was very difficult to imagine that one could not summit on a clear day and that there were many factors that determine a successful climb.  The rest  of the first day’s climb is easy into Camp Muir.  Muir is an assortment of small buildings situated on a ridge that separates the snowfield from the Cowlitz Glacier.  The buildings serve as a way station for climbers, and IMG has a small room there where the team can bunk down for the night.  The room is about 20 x 20 feet, and is a couple of plywood shelves to role out your sleeping bags.  Pretty small quarters, but shelter from the wind (it also turns out the expedition members don’t really snore nor have nocturnal gaseous emissions).  The IMG guides have a tent that serves both as the communal restaurant and their sleeping quarters.  Dinner at the IMG tent was a very pleasant surprise, and suddenly I felt very guilt for my mental grousing about carrying that five pounds of community food.  Dinner serves as a chance for all the team members to learn about each other — and I learned far more than I ever thought possible about pediatric dentistry, the incredible attributes associated with living in Coeur d’Arlene and climbing Aconcagua (I am jealous).


A sketch of the east side of Rainier (from Crandell, 1969). The path for our ascent crosses the head of Cowlitz Glacier, then follows the rock spur below Gibraltar Rock up to cirque of Ingraham Glacier over looking Little Tahoma Peak. The original summit of Rainier went from Point Success to Liberty Cap – before a major eruption 5500 years ago, Rainier was 16,000 feet high.

Friday morning the trek really begins — we practice ice axe skills, crampons on ice, and roping up groups of climbers.  We cross over Cowlitz Glacier and then have a short hike up what is called Cathedral Gap;  the Gap section is bare rock and our passage is in our crampons, a first distasteful snippet of walking on rock and dirt while wearing sharp spikes of metal.  After a relatively short hike we arrive at the high camp located on the upper reaches of Ingraham Glacier.  Ingraham Flats is a moderately sloping section of ice at an elevation of 11,500 ft.  The camp is four tents for the climbers, two more tents for the guides, and small kitchen carved in the ice and snow.  The views are breath taking; the sounds are unnerving.  The Flats are framed by Gibraltar Rock to the south and the Disappoint Cleaver to the north.  Gibraltar lords over the camp as vertical cliff of nearly 800 feet, composed of layers of eruptions and lahars past.  Every few hours rocks fall from the cliffs, a not so subtle reminder that Rainier is always changing.  I also peer up at the ice of the head of Ingraham Glacier and think about the disastrous ice fall in 1981 that took the lives of 11 climbers.  It is the worst climbing accident in American history, and to be in it’s shadow is a reminder that gravity is unforgiving.  I decide it is best not to ask about the accident with the other members of the team.


High Camp – Ingraham Flats, on Ingraham Glacier.  Over my left shoulder is the Cleaver, a nasty stretch of rock that is the heart of the climb to the summit (which is visible some 3000 feet above us in the center of the photo).

We have “dinner” at 3:45 on Friday so that we can be in the tents by 5:30 pm.  This is to facilitate a 1:00 am wake up call and a 2 am debarkation for the summit.  Sleep that night seems fine for me (better than most of my hotel visits to Washington DC every couple of weeks), but most of the team is beginning to feel the effects of altitude.  Living at 7400 feet elevation has its rewards!  Breakfast at 1:15 is instant oatmeal and coffee.  I opt for multiple cups of coffee and pass on the oatmeal.  At 11,500 the boiling point of water is about 185 degrees F instead of the sea level value of 212 degrees, so the coffee is tepid.  No matter, it is still nice fuel.  The morning is cool – my thermometer that I left just outside the tent reads 28 degrees F.  The wind is still though, so it is quite easy to dress comfortably.  Unfortunately, before we rope up to cross the glacier and head up the cleaver we remove layers to assure that we don’t over heat on the climb.  That means it is cold when we start our trek.  The climb is steep, and the half moon gives a nice glow, but mostly you look at the ground in front of you illuminated by your head lamp as travel.


High Camp from Disappointment Cleaver. This picture was taken on the descent, mid-morning.  The tiny dots are our tents at the high camp.

The Cleaver is an 800′ elevation climb on rocks.  It is technically the most difficult part of the entire ascent.  Not particularly physically challenging, but the combination of large blocks of Andesite, crumbly scoria, and even some obsidian means that every step of the crampon encased boot is a challenge. Around 3:30 we finally finish with the Cleaver, and are back on the welcome crunch of ice.  The guides lead us back and forth up the south face of Rainier until we finally cross the lip of West Crater about 7 am.  The sun is just rising, and the winds are calm.  Unbelievably majestic.  Crossing the lip of the crater is considered a summit, but I know that we are across the crater from the true high point on Rainier.  Several of us drop our packs and hike the couple of hundred yards to the northwestern rim and climb up to the Columbia Crest, the “true” summit of Rainier.  We arrive there about 7:30, and revel in the success of the trek.


Summit Team at Columbia Ridge. Just below me is the USGS marker for the elevation.  The marker was placed in 1956 – my birth year.

The views from the summit are both spectacular and disappointing. The skies are clear, and one can easily pick out every major volcano in the Cascades well into Oregon. However, the humidity in the air gives a sense of haze in the distance that one never sees from the summit of a 14er in Colorado. The crater itself is magnificent. A stone circle created by an eruption a few thousand years ago, it has dozens of fumaroles all along the rim. Wisps of steam give hint to the hot rock not far below the surface. I applied the sniff test to several of the fumaroles, and only caught the faintest notion of sulfur; mostly was just moist stream.


West Crater

Around 8 am we began our long trip reversing our footsteps back to Paradise. By my Garmin we had hiked 12.2 miles and with the ups and downs (mostly ups!) we had gained 9600 feet elevation. The journey down was more difficult than I expected – not because it was a physical challenge, but because the sun was shining and the views were extraordinary! I wanted to stare and ponder the magic landscape, which meant I did not want to focus on traveling on a rope along an icy and steep trail. The descent back to the top of the Cleaver went by uneventfully, and I was able to get a picture of the moon setting over the top Mt. Rainier.


Rainier Descent – moon setting over the rim of the crater.

The traverse down the Cleaver was by far the most difficult part of trip down. We are all a little tired, and those damn boots and crampons! I did manage to stab myself in the left leg with the crampons from my right boot. I drew blood, and it is only appropriate as a sacrifice to a great mountain. We finally get back to high camp for a brief rest, and some lunch. The journey back to Camp Muir was pretty trivial, and we stop for some water at the IMG tent. All that stands before us and the end of the trek is the Muir snowfield – how hard can that be? However, we decide to keep on the crampons to cross the field since it is soft and slick. Drudgery! But unexpectedly, the slog was made tolerable by the fact that it was Saturday, and there was a menagerie of folks climbing the snowfield from Paradise. We saw people in shorts, skirts, tennis shoes, formal wear, and of course, flip flops! Consider that these snowfield adventurers had invested hiking more than 3 miles and 2000 feet elevation gain, you have to wonder how much thought went into their apparel. One of the most humorous moments of the entire journey was when one of our teammates engaged a woman in a long dress in conversation on the snow and said “you can do it!”. He was being positive, but also preposterous! Finally, at Pebble Creek we shed our boots and crampons, and all is right with the universe.

The trek up Rainier was a spectacular experience. I am fortunate to have combined the wonder of a high mountain climb with a favorable group of colleagues, and wonderful guides. I could not have been more delighted – but of course, I got something a little extra. On the flight home Sunday morning the American Airlines flight to Dallas took off to the south out of SEATAC and flew towards Rainier. Once we reached the Nisqually River the pilot took a hard left and flew right over Paradise, and suddenly out my window was the entire picture of my trek. Fabulous!


Passing over Rainier on the way home (9/14/14). The image is high resolution so click on it and expand. The various way stations are labeled.

Rainier will one day erupt, and will no longer be the high point of the Cascades. I am grateful that I got to experience the great mountain in its finest state – and mood.

The Zen of Stephanite: Collecting Minerals in the Era of Art

The most beautiful experience we can have is the mysterious – the fundamental emotion which stands at the cradle of true art and true science.  Albert Einstein


A family gathering of Stephanite – Ag5SbS4 – a black and rather plain silver mineral. From the left, a single crystal from Pribram (crystal is 4.5 cm high, scale for other specimens), a cluster of bright crystals from the Husky Mine, Yukon, Canada, and dozens of prismatic crystals on matrix from Joachimstahl, Bohemia.

I have been collecting minerals for 54 years, and in that half century there has been a dramatic evolution of the “mineral hobby”. Perhaps this evolution is normal, but today the hobby is barely connected to the rock hound roots of my past. I was recently offered an incredible (a more descriptive adjective would be “obscene”) sum for one of my mineral specimens. The dollar amount was more than 3 times the annual salary I drew when I started as an assistant professor at the University of Arizona in 1983. Rather than being pleased with the offer and congratulating myself on the thoughtful investment strategy I must have concocted all those years ago, I was despondent. The collector persisted, and told me the “specimen was a masterpiece, a work of art”. Art!  Indeed I collect minerals because they are meaningful artifacts – the perfect combination of science, human history and perfection in nature, but the way the term “art” was being used reduced the specimen to the calculus of trophy hunting.

My depression was an expression of  the culmination of frustrations and fascinations with the changes in mineral market I have observed.  In the 1960s and early 70s most minerals were within the economic reach of a dedicated mineral collector. There was a “top end” to be sure, and certainly many minerals fetched prices that exceeded the cost of a new automobile.  However, there were many collectors that built incredible collections on a bargain budget.  These collectors were driven by a passion I can relate to – most were very knowledgeable about mineralogy and had a rudimentary understanding of the geology.  In the early 1970s there was a strong push by a group of mineral dealers and curators to describe some minerals as “natural works of art”. Paul Desautels was at the vanguard of this movement, and in 1968 he published The Mineral Kingdom, which is arguably the most influential mineral book in history.


The Mineral Kingdom – a remarkably influential book published by the curator at the Smithsonian in 1968. Although perfection and beauty in mineral specimens had long been sought, The Mineral Kingdom laid out why mineral specimens should be thought of as art.

I received a copy of The Mineral Kingdom for Christmas in 1970.  I loved the book (still do) – it has chapters on the science of minerals, the history of minerals, famous localities and countless historical drawings and photographs.  It also has chapters entitled “Mineral Masterpieces” and “The Connoisseur”.  The opening soliloquy of the chapter on Mineral Masterpieces: “Classic mineral specimens, like great works of art, achieve their status through experts’ judgments”.  This sentence is, of course, 100 percent factual – and I would be very hypocritical to suggest that I don’t covet, pursue, and cherish mineral masterpieces.  However, this tie to art has driven the mineral market in the last 40 years in ways that are not healthy.  In the art world the top end of the market seems to have little relationship to driving prices and value at the low end of the market.  That is not true in the mineral collecting world – prices for top pieces provide justification for pricing lesser specimens.  The conversation goes like this:  I saw a Kongsberg silver wire that was just sold for $300,000 dollars, therefore this lesser Kongsberg must be worth at least $40,000!  In the art world no one says that a 25 million dollar Rembrandt sketch of a smiling woman means that similar drawing by Elmer Fudd justifies a price of 1 million dollars.

In my opinion mineral collecting in this era of “minerals as art” has made minerals much less accessible to beginning collectors and those of modest means.  The market place is still adjusting, and Darwinian forces will most certainly win out.  Luckily, there are still some minerals that have resisted the art trends — mostly very common minerals, very rare minerals, or those that are considered “ugly”.  Being a silver collector I am fortunate that some of the silver species fall in later two categories.  One of these is stephanite – and as Einstein notes, it is mysterious mineral, at the intersection of science and art.

Minerals as Art

There is a vast body of literature devoted to the psychology and motivations of collectors of high priced art. In truth, art collectors are probably not a lot different that collectors of “any objects” – baseball cards, model trains, stamps, coins, etc. However, there is a special aura associated with art collecting. In November, 2013 Christie’s auctioned the Francis Bacon painting “Three Studies of Lucian Freud” for $142.4 million dollars (there are rumors of private art sales for even more – $250 million for a Cezanne in 2011, for example). To me, the Bacon painting is just flat; it does not move me in any way.


Francis Bacon’s Three Studies of Lucian Freud, painted in 1969. Christie’s sold the painting in auction for more than 142 million dollars, which 7 bidders competing for the right to own….these three panels.

142 million dollars?  Those that analyze the art market claim that the value is driven by both passion and competition.  The passion is easy to understand, but it is the competition that propels the price sky high.  Competition in this case is not the same as demand for a rare resource, although that is a factor.  Rather, the competition is about denying others the trophy.  This lust for winning strikes a deep nerve.  The ultimate trophy is an important aspect in mineral collecting today.

In 2012 the Economist magazine profiled several studies on the art market, including a Barclays Bank report entitled “Profit or Pleasure? Exploring the Motivations Behind Treasure Trends”. The report interviewed 2000 art collectors and dealers (all very rich people) from 17 different countries, and found that this rich clique had a strong sense of community. The collectors, and dealers that cater to them, shared that buying art engendered feelings of victory, cultural superiority and established a badge of social distinction. The sense of community also leads to mechanism of validation – these collectors want what the other collectors want, and were actually quite conservative in branching out on their own, and rarely are trend setters.

Art Basel is an annual art fair in Switzerland that is sort of like the annual Tucson Gem and Mineral Show. Some 300 plus very high end galleries put on a show that is a “do not miss” event for collectors and museums. In the Barclay report there were a number of dealers that talked about their strategies for selling their wares. They often make a list of people they think would be a “good home” for a piece of art, and then show the piece only to those queued on the list. Collectors that have a piece reserved for them personally are nearly twice as likely to buy the art work than if it is openly displayed in a gallery. This last year Art Basel tried an experiment of opening the art show early to select “VIPs”; lesser VIPs had to wait a few hours before they could buy. Predictably, the lesser VIPs were angry – mostly about their demotion in status.


Ikons, a 2007 publication by mineral dealer Wayne Thompson, was a tribute to minerals as art. Thompson makes the argument that visual presence of certain specimens makes them “ikons” — as the art standard for the mineral community.

The description of Art Basel could easily be Tucson if the words “art works” and “mineral specimens” are interchanged. Today the highest end mineral specimens are sold at “pre-show” gatherings at resorts like Westward Look. The well healed arrive a week before the main show in downtown Tucson, and visit the pre-shows. They ask if dealers have anything set aside for them – and the successful dealer always has a stash hidden away, under the bed or in the bathroom, that is just to be viewed by the preferred customer. The “lesser collectors” (people like me – knowledgeable but never a VIP) then can browse the more modest minerals on the shelves of the display cases. I am told that the preferred customers account for 10 percent of the sales in volume and 75 percent of the monetary value.

In 2007 Wayne Thompson published a special volume in the Mineralogical Record. This volume was called  Ikons – Classic and Contemporary Masterpieces.  It is a homage to minerals as art, and makes the point that iconic specimens are as important at art masterpieces.  However, there is a huge disconnect between pricing for mineral masterpieces and lesser specimens.  It is always difficult to know what an “ikon” has sold for — rumors help drive up prices — but a simple example illustrates this dilemma.


The Aztec Sun – legrandite — as displayed in the MIM museum in Beirut. This is one of the world’s most famous mineral specimens, and now is a standard for comparison for all legrandite.

One of the most famous mineral specimens in world is the Aztec Sun – a spectacular spray of lemon yellow legrandeite from Mapimi, Mexico. Today the Aztec Sun resides in a fabulous museum, MIM, located in Beirut, Lebanon. This specimen use to be in the Miguel Romero mineral collection, and I had the honor of curating the Romero collection for 5 years.  When it was decided to sell the Romero collection this piece was the subject of much angst on pricing.  How much was it worth?  I don’t know what the actual selling price was, but the rumor was 2 million dollars.  It is about 20 cm high, and really, a rather simple mineral; (Zn[AsO4] [OH].H2O).  The rumored sales price reverberated through the mineral community, and I know of at least 3 cases where a mineral dealer raised their prices on the legrandite specimens in their stock — in one case the repricing was an escalation by a factor of 3!  Why?  The specimen that suddenly carried a hefty price tag was hardly the Aztec Sun; in fact, it was a rather unremarkable 4 cm cluster of slightly damaged crystals on brown limonite matrix.  A decade later that specimen is still for sale, although now only twice its original price tag.

This dragging up in value of lesser specimens by the sale prices of the “ikons” is a perplexing problem in the mineral hobby.  It seems to suggest that a mineral species or its locality is the equivalent to a named artist – i.e., legrandite = Van Gogh.  It is difficult to know what the market trend will be for minerals – will they become mineral specimens again, or only works of art?


Stephanite is one of the four “common” silver sulfosalts – the others being polybasite, pyrargyrite, and proustite.  Stephanite is known from hundreds of localities, and in the past was a very important ore of silver (in fact, stephanite along with acanthite, was the primary ore at Comstock Lode in Nevada where 200 million ounces of silver were produced). Despite its relative abundance and chemical kinship to the other more highly coveted silver sulfosalts, stephanite is hardly ever considered a “classic”. A picture of stephanite has never graced the cover of Mineralogical Record, and it does not even get a tiny shout-out in Ikons. Stephanite is black, rarely lusterous, and mostly found in small crystals. However, it is a mineral with a rich history, and is an important artifact from every historic silver mining camp in the world. It well may be the antidote to minerals-as-art movement. Stephanite is where I find my Zen.

4.5 cm tall crystal from Pribram, Czech Republic.  Jeff Scovil photo.

4.5 cm tall crystal from Pribram, Czech Republic. Jeff Scovil photo.

If there was a “world class” stephanite it would probably be the crystal pictured above from Pribram, Czech.  The crystal is of extraordinary size for the species, and a bright luster.  The mines of Pribram are quite ancient – silver mining is known here from the 13th century.  During the 19th century the Pribram mines were some of the most technologically advanced in the world, and were the first to have shafts that descended 1000 meters below the surface.  The best silver species specimens were mostly mined before 1860, and are very well represented in the Narodni Museum in Prague. The pictured stephanite is the best I know of, although it is difficult to document its lineage.  Below are the mineral labels still with the specimen; it came to me through Gene Schlepp.

Labels for the Pribram stephanite.  Only the last label is recognizable to me - Rukin Jelks (who was a very highly regarded southern Arizona collector).

Labels for the Pribram stephanite. The H. Maucher label most be from the late 1930s.  Rukin Jelks (who was a very highly regarded southern Arizona collector) was the last owner before passing the specimen through Western Minerals in Tucson.

The common silver sulfosalts are part of a group of complex chalcogenides with a chemical formula AxBySn where A = Ag, B = As, Sb or Bi, and the S is sulfur. For stephanite the formula is Ag5SbS4. The fact that polybasite, proustite and pyrargyrite are part of the same group means that they all have similar properties structurally – and which of these mineral forms in a geologic environment mostly depends on temperatures and pressures. In almost all cases, the silver sulfosalts form in epithermal veins – hydrothermally driven fluids.  Stephanite is the last of these minerals to precipitate out of solution – in fact, stephanite  is not stable above 197 degrees C.  Above this temperature stephanite decomposes into pyrargyrite and acanthite.


Stephanite on polybasite, Fresnillo, Zacatecas, Mexico.  The stephanite is the last silver mineral formed in most epithermal silver veins.

The specimen pictured above documents the paragenesis of stephanite from Fresnillo, Zacatecas, Mexico.  The core of the specimen (with is 3.5 cm high) is a polybasite crystal.  Sprinkled across the polybasite are stephanite crystals which grew on the polybasite as the vein fluids cooled.  Fresnillo is an amazing silver deposit, and source of some of the very best silver sulfosalt specimens in existence.   Mining at Fresnillo dates from Spanish Colonial time, although few specimens survived before the mid 1970’s.  Fresnillo is often mentioned as an important silver district in historical literature, but it really was quite unremarkable. The district was nearly abandoned in the 1970’s, but a desperation drilling program discovered a blind vein system a couple of kilometers southeast of the main workings.  These veins average 800 g/ton of silver, and occasionally grade to 2000 g/ton.  Seams of solid pyrargyrite 35 cm thick have been reported and individual crystals more than 10 cm in length have been collected.  The district has now produced more than a billion ounces of silver (Kongsberg only produced 43 million ounces of silver!), and exploration in the surrounding region has located huge reserves. Many of the best specimens came out in the period of time 1992-1999;  I was extremely fortunate to have seen most of the best material, and acquired the core of my collection from Dave Bunk during this time.

Stephanite was first mentioned in literature in 1546 by Georgius Agricola.  Agricola, born Georg Bauer, is the “father of mineralogy”;  he was the town physician at the Bohemian mining center of Joachimsthal, and wrote extensively on the geology of the region. In his 1546 text  De Natura Fossilium Agricola described the mineral as schwarzerz in reference to its black color.  It is later referred to with various names – both in latin and german – as black silver ore and brittle silver ore.  In 1845 Wilhelm Haidinger proposed the modern name of stephanite in honor of the Archduke of Austria, Stephan Franz Victor.  Archduke Stephan was one of many nobelmen of the time that built “natural history cabinets” — however his was just extraordinary!  He acquired more than 20,000 specimens, mainly from the mines of Bohemia.  When he died the collection went to the House of Oldenburg. Much of it was sold, but some of the specimens remain in  the Natural History Museum in Berlin.  The Archduke’s labels are distinctive, and much coveted by mineral collectors today.


A complex cluster of stephanite crystals from Freiberg, Saxony. The specimen is a little over 5 cm tall. The specimen was originally in the Archduke Stephan collection, and has passed through at least 5 collections before coming to me.

Stephanite belongs to orthorhombic crystal class, although twining on the prism planes is extremely common giving rise to pseudo hexagonal crystals. There are three dominate habits for stephanite: (1) thin, hexagonal plates that can be as large as the size of a US quarter, (2) elgonated hexagonal prisms (like the Pribram stephanite pictured above), and (3) tubular clusters of crystals that form branching clusters.  Stephanite is iron-black in color and sometimes has a bright luster.  There are numerous mineralogical texts that claim the bright luster will dull with exposure to sun light, but I have no evidence of that, nor do I know what the physical mechanism would be.


Stephanite prism, Fresnillo, Zacatecas, Mexico. A classic pseudo hexagonal prism, 2.7 cm tall. Some of the very best stephanotis ever recovered came from Fresnillo in the late 1990s. Jesse La Plante photography.

The largest stephanite known are from a modest mine, the Las Chispas, located near Arizpe, Sonora, Mexico.  The production history of the Las Chispas is mixed; it was interrupted by revolution, strikes and seizure. The total silver produced probably did not exceed 20 million ounces of silver, but a very enlightened mine manger, Edward Dufourcq collected specimens and the mine owner, Pedrazzini, donated many to the Columbia School of Mines.  Dufourcq wrote the following in an article published in 1910; “The crystallized specimens of the silver minerals are especially noteworthy….What is probably the largest single specimen of stephanite in the world was presented by Mr. Peddrazzini to the Egleston collection at the Columbia School of mines, where there are also a number of other specimens of polybasite and stephanite, as well as a remarkable specimen representing the transition of an argentite crystal into cerargyrite and a fine embolite. The American Museum of National Hisotry in New York also has, from this mine (the Las Chispas), what is probably the largest mass of polybasite crystals ever taken out in one piece. This originally weighed over 65 lb., but was broken into two parts during the time it was in transit from Sonora to New York”.  When I was curator at the University of Arizona Mineral Museum we received one of the two pieces of the “65 pound” polybasite crystal group in trade – it only weighed 13 pounds!  The stephanite groups are smaller than the polybasites, but still giants for the species.  The largest I know of is a cluster of crystals 12 cm across.  The photo below is a very large crystal group in my collection.


Stephanite, Arizpe, Sonora, Mexico. A large cluster of crystals from the Las Chispas mine; the specimen as displayed is 6.8 cm across. Jesse La Plante photograph.

Stephanite has always been a favorite of serious collectors, even if it is not in “art world”.  Below is the mineral advertisement from the Foote Mineral Company of Philadelphia. Albert Edward Foote, who arguably is the most famous mineral dealer in American history, sold minerals from 1875 until his death in 1895 (the company passed to his son, a good dealer in his own right, and then to others and still exists today). The ad below includes a reference to “Stephanite, fine crystals, 75 cts to $5″ from Germany.


Mineral advertisement from A.E. Foote Minerals published in 1894. The stephanite specimen pictured below was one that was sold with this ad, and costs $3 dollars 120 years ago.

I bought a stephanite in 1988 (pictured below) that came with a photocopy of this ad, and a note that the specimen was purchased from the ad for $3 dollars in 1894.  It is impossible to confirm that this is indeed true, but it does provide a fanciful barometer for price increases.  I bought the specimen for 450 dollars – which translates into an escalation of a factor of 150.  There are many “inflation calculators” that can help give a sense of the rising costs overall.  These calculators say that consumer goods have increased by a factor of 20 over in the last 100 years (averages 3% a year), thus stephanite has been a “good” investment. But the 3% annual inflation is highly misleading – some commodities have increased in value and others have dropped tremendously (for example, the cost of electricity).  Another way to compare the value of the price increase is to compare it to a specific commodity through time.  For a mineral collector the perfect barometer is the cost of a pint of beer (mineral collectors, in general, think in terms of specimens and beer).  Using the average price for a pint of beer in a bar in New York City in 1900, and again in 2000, the cost increase was a factor of 180 (data from the Economist). In other words, stephanite prices have not kept up with the price of beer.  This truly means that stephanite is not art!


Stephanite, Frieberg, Saxony, Germany. A large thumbnail, originally bought from the A.E. Foote mineral company in 1894. Jesse La Plante photograph.

Mineral Collecting in the Era of Art

There are a number of ways to evaluate the value of a mineral specimen. These include rarity, locality, pedigree, and aesthetic beauty. Beyond the specific character of an individual specimen, it can have value as part of a collection, documenting the nature of a particular mine or geological deposit. Unfortunately, the evaluation criteria are highly subjective and subject to changes in mineral availability and popular notions of aesthetic beauty. In the last 20-30 years the “masterpiece” or trophy mineral has dominated the pricing paradigm in the hobby, and dramatically skewed the sense of worth.  Wendell Wilson and John White (1977) conducted an experiment in specimen appraisal by asking a group of museum curators, collectors, and mineral dealers to estimate the cost of ten different mineral specimens.  The survey was conducted twice, four years apart.  Although the time separation was too short to gauge slowly varying trends (like specimen size), it did capture the strong trends in trophy hunting. During this four-year period the average mineral specimen increased in value by 190%! Although not immediately obvious, this dramatic increase caused a cosmic shift in mineral dealing.  Dealers began to view specimens as an investment and certain new collectors demanded a high rate of return.  Those dealers that understood the trend were able to adapt the business practices of the art market.  However, this adaptation had some very unexpected consequences – all mineral prices became pegged to the highest priced trophies.  This meant that “esthetic” but otherwise unremarkable mineral specimens rose in marketing value at an unprecedented rate.  By the early part of the 2000s large numbers of collectors had either stopped buying, or were now buying specimens with much less frequency. Today, the mineral collecting hobby is changed – and will continue to change — and is no longer the bastion of “rock hounds”.  The question I am most frequently asked today is “how much is that worth”.  Almost never am I asked about why a specimen is important, or why I enjoy it.

Fortunately, I can still enjoy my hobby through scholarship, and the pursuit of a few, largely unappreciated species.  The Zen of Stephanite.


2.8 cm prism of stephanite with white calcite crystals, from Fresnillo, Zacatecas, Mexico.