SANDIN E. PHILLIPSON, Ph.D.

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Adventures in Geology, Petrography, and Mining

Adventures in Bolivia
As a graduate student, I finally had the opportunity to work on a project in southern Bolivia. Although I had spent previous summers camping alone while conducting fieldwork in remote areas, this was to be my first journey overseas, to a country known variously for coca growing, revolution, and the final resting place of Butch Cassidy and the Sundance Kid.
La Paz is nestled in a series of steep valleys that are eroded in a jagged, blasted moonscape of sun-baked volcanic rock. One of the city parks is called "Valle de la Lunas" or Valley of the Moon. The city has sprawled up the valley slopes onto the Altiplano, or high desert. As my taxi drove from the airport over the lip of the high desert, the city was spread out below, partially obscured through a haze of heavy smog. After finding the company office, a driver took me to a hotel in the old part of the city, popular with young, dominantly British and Spanish backpackers. Left to my own devices for several days, I taught myself the phrases and words to order breakfast and dinner, and wandered through the open-air market to practice my nascent Spanish skills on vendors of flashlights, jeans, and trilobite fossils. I found Bolivians to be the friendliest of people, who seemed to delight in talking to a Norteamericano. At first, I felt no ill effects from climbing the steep streets in what has been described as the World’s highest-altitude capitol city. After several days, altitude sickness left me with a feeling of exhaustion and constant headache in spite of six weeks of hiking in the Colorado Rockies.
At last I was to depart for the exploration camp in southern Bolivia, as the pickup laden with fuel drums and survey stakes arrived to collect me. My driver, Nicco, guided the pickup through the bustling, chaotic streets of La Paz and we rolled south on a two-lane, newly paved highway toward Oruro, a hot, dusty, windblown town that represents the end of pavement. There, the sun-baked main street was covered in a one-inch layer of dust that was excited into whirling vortexes as lines of Volvo flatbed trucks trundled through. Gray, windblown silt covered the cobblestone street, sidewalks, building facades, and withered decorative trees to produce a desolate dreamscape devoid of color. We rolled through a featureless landscape beneath an endless expanse of blue sky and mercilessly bright sun. As the daylight began to wane, the highway degenerated into a pair of deep ruts across the featureless desert, passing desolate adobe towns. We forded streams of frigid meltwater from the Cordillera Oriental, often breaking a thin film of ice. Night fell and still we rolled south, now across the Salar de Uyuni salt flat. Despite the heater in the Mazda 4x4, the cold crept in, and in the ghostly play of the headlights, the shimmering white deposits of salt might have been snow drifts. Time dragged, with only the constant rumble of the tires on hardpan marking a cadence in the darkness that surrounded the small, heated compartment of the pickup. At last we reached a town, a sign of human habitation in what seemed increasingly like a harsh wilderness. Not a single light bulb was evident as we thumped slowly over the cobbled streets. Dark shapes shuffled along the sidewalks, and the shadows of adobe buildings rose and fell, capering in the glare of the headlights. Stars, bright and brilliant as diamonds, but equally as cold, seemed to provide the only other light. Amidst this scene of harsh desolation, the corpses of dogs littered the streets, frozen stiff where they had ultimately succumbed to the uncaring elements.
After another three hours of crawling through the frigid darkness, the road seemed nothing more than a gully, with sagebrush whipping the sides of the truck. Almost imperceptibly, we left the desert and a sheer rock wall suddenly loomed out of the darkness. The truck climbed the rapidly rising road, which clung to the side of the cliff, and the engine whined in protest at the exertion caused by the steep grade and thin air. In the days to come, my own heart and lungs would register a similar wheezing protest. We passed through a looming cleft in the rock wall, beneath towering ramparts massed in the impenetrable gloom. Suddenly, the truck stopped and we had arrived. Arrived where? In the dim light, I could barely discern an adobe wall. There were no lights, no sound of people or animals, and no hum of machines that we have come to expect virtually everywhere in North America. In the dead quiet, pitch black surroundings, I might have been standing in a cavern instead of in front of the quadrille where I would live for the next four months. I had arrived in Bolivia.

Treasure in the Andes
I awoke to strange surroundings, my first view of the plaster-peeling room in which I had spent the night being afforded by the early-morning sunrise on the Bolivian Altiplano. After arriving near midnight in the frigid darkness of the high desert, my thoughts had been only of how quickly I could unpack my sleeping bag and crawl in. Now as I peered out of the window, it became apparent that I was in a quadrille, the famous architectural style of squares-within-a-square that is a hallmark of the former Spanish Colonial Empire from California to South America. My "room" consisted of a small shack, which with a series of other small, straw-thatched, adobe huts, defined the walls around a central courtyard paved with flagstones. There was no heat source, and thus my morning dressing routine required only that I emerge from my sleeping bag, it having been too cold to consider removing my several layers of clothing the previous night.
The courtyard upon which I gazed had been the home of a Polish mining engineer who came to seek his fortune in the fabled land of the Inca, drawn, as many before him, by stories of fabulous wealth. The first reports of silver to reach the Spanish Colonial authorities came from a Spanish priest in 1537, although the Inca had undoubtedly extracted the precious metal for their own use before that. I had also come to seek my fortune in this place, not by extracting tons of silver ore, but by unraveling the geological history as a subject of thesis research. In fact, I was living my dream of working as an exploration geologist amid remote, rugged surroundings, as the only Norteamericano for a hundred, and probably three hundred, miles.
I exited the courtyard through a low wooden door that represented the only means of egress, and found myself on a narrow, cobblestone street bounded by the adobe walls of other quadrilles. The stygian darkness that accompanied my arrival the previous night had concealed the size of the town. I trudged up the street, panting for breath in the thin, 12,000-foot air. Upon reaching the outskirts of the village, which required only a few minutes, I assailed a ridge and, upon reaching the crest, took in what the view afforded. I surveyed a desolate landscape devoid of trees or vegetation, save for the small, wind-worn tufts of spiked grass that dotted the hillsides. The Bolivian Altiplano stretched to the horizon in all directions, broken only by jagged mountains that floated in a shimmering, salt-tinged mirage in the distance. The bright blue sky similarly stretched everywhere to the horizon, unblemished by the smallest cloud, until merging with land in the parallax of distance. The blazing white sun constituted the sole occupant of the sky, and although its rays burned my skin and faded my clothes within days, no warmth seemed to emanate from that orb. Instead, the biting wind tore through my layers of clothes, chilling me even as I was being sunburned. The thin air, lack of vegetation to provide perspective of distance, the expanse of blue sky, and blazing sun combined to induce a detached, dreamlike state of near-hypoxia in which concepts of distance and time ceased to have meaning.
The village below was laid out in a grid, consisting of four streets by five streets, and apparently little changed since the 16th Century. There was no electricity, no running water, and no source of heat except bundles of mesquite acquired at some remote location. The source of water that was available was frozen except for two hours in the afternoon. A haze of mesquite smoke hung over the village, nestled in a shallow valley within a larger depression. The village appeared to have some natural fortification, hidden by a ring of volcanic hills. The valley breached the ring of hills along a fault zone, which fractured the rock into three giant spires. In local lore, these three great rock spires were known as Tres Gigantes, or the Three Giants, and appeared in pictures with the patron saint of the town. Who knows but that the founding saint, Saint Christopher, might have been the same Spanish priest that first reported the presence of silver to the outside world?
The surrounding hills were white, the volcanic rock having been altered to the consistency of powdered sugar by acidic solutions. But rather than tasting sweet like sugar, the powdery rock was alkaline, like corroded battery cables. Far from being associated with the feelings of defeat and failure evinced by a dead battery, this natural acid-bleached rock constituted the bulk of the silver resource at the site and was a source of great excitement. The countless miners who toiled to wrest high-grade ore from wide silver veins would have found it impossible to recognize this as silver ore. How ironic that for centuries, miners had removed silver ore from the district until all thought it exhausted, when in fact the vast bulk of silver occurred in this white, crumbly rock, unseen to the naked eye. As often occurs in life, great treasure may lie at our very feet if only we could but recognize it.

Stay Out of That Old Mine!
It seems like the most adventurous thing in the world. That dark opening in the hillside beckons, tantalizes, excites. What wondrous treasures await discovery inside? What artifacts might remain in this time capsule, mute testimony to an era when grizzled men moved tons of rock in pursuit of their dreams? Such is the poetic, romance-novel appeal that might induce you to take leave of your senses and crawl into an old mine. Thousands of such small openings are scattered throughout the country. Although most common in the historically "hard rock" Western mining states, they can also be found in the old lead and copper districts of the Midwest. In reality, multiple dangers lurk beyond the pale ring of light that filters through the adit mouth.
While scoping out a field area for a thesis project, I spent six weeks camping and hiking in the West Elk Mountains, in the Colorado Rockies. My days were spent tramping around the flanks of a majestic 13,000-foot peak, chosen due to tantalizing reports of silver mining activity around 1900. During my ramblings, I came across several old mine workings. Some were simply short adits driven into the hillside, designed to test for the presence of silver, copper, and lead minerals that might be distributed within the contact zone of the porphyry intrusive that defined the mountain peak. Other workings, though small, were relatively more sophisticated and had rail tracks extending from the passageways out onto the progressively extended pile of fine waste rock. I explored each of these, sometimes crawling over piles of rock that had fallen from the roof or ribs, or widening a hole and sliding down the pile of washed-in dirt to reach the adit floor.
This really was the height of folly, as I was alone in the wilderness and had no idea of the potential dangers. I currently work in the field of ground control engineering, and have firsthand knowledge of numerous fatalities that occurred in active mines when rock fell out of the roof without warning. I have also become more familiar with the extensive engineering design work, and variety of support systems, required to develop and maintain a mine opening. The "old timers" were often lucky by developing small openings in hard rock, but modern mining engineering indicates that time does not favor stability.
A more insidious danger is represented by a lack of breathable air. In sealed underground openings, the air may have become "stale" by not being circulated through the outside. In modern mines, a staff is devoted to designing and maintaining ventilation systems that cycle fresh air through the mine. Some gases displace oxygen, but are colorless and odorless and give no warning of danger until the person suddenly realizes that they feel as though they have been holding their breath for several minutes. This is a condition known to miners as "black damp" that can cause loss of consciousness or death. While working in Bolivia, I entered over a dozen small mines in a district that had been developed initially by the Spanish, or perhaps even the Inca, and later by a Polish mining engineer in the early 1900’s. The most modern operation had closed in the 1980’s, when the underground portion of the mine was abandoned as uneconomical, but a small open pit was developed that intersected some of the old workings. As a geologist working to unravel the geological history of this area, I entered the mine to document the relationships between intrusive phases. As I was intently concentrating on the last face of the mine, trying to decide if the rock was rhyodacite or dacite, I suddenly noticed a warm, tingly, numb sensation in my nose and lips. Panicked, I exhaled what little air remained in my lungs and held my breath, while at the same time wheeling and sprinting back up the tunnel. Weird, ghastly shapes of rotten canvas and timbers danced in the shadows thrown by my flashlight. I had little hope of sprinting the nearly 300 yards to the mine mouth, but as gray spots floated before my eyes, I determined to keep my legs pumping in hopes that I could at least get out of what might only be a pocket of bad air. Then I saw a sliver of light where the floor of the open pit had intersected the tunnel. Fresh air! I ran to the cut and gulped in the thin mountain air. Although the air smelled like decaying sulfides, at least the threat of black damp was gone, and so my panic subsided enough to allow me to walk briskly out of the mine.
Crawling into an old mine, in which no miner or engineer has evaluated the condition for decades, is something that I would now consider as pure stupidity. No shiny bauble or rusty artifact is worth it. Take a picture of that beckoning hole, and then leave it alone. Remember that the "old timers" have already taken out the rock and dumped it on the ground for you. Satisfy yourself with a little piece of azurite, malachite, chalcopyrite, or pyrite from the dump pile if you must have a souvenir, but stay out of that mine!

Click here to see pictures of rocks under a microscope!
Click here to see pictures of metallic ore minerals under a microscope!