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Posts Tagged ‘spor mountains’

The second part of the video on beryllium is now finished. You can watch it here:

This video has literally been 2 1/2 years in the making; my students Amy Zirbes and Nathan Jane videotaped our interview with subject expert Phil Sabey, the Manager of Technology and Quality at the Delta mill, in NOvember, 2007. This video discusses the history of mining beryllium at the mine site in the Spor Mountains of western Utah, including how the bertrandite deposit was discovered, and the land rush that occurred as a result (including an incident involving Maxie Anderson, who was head of Ranchers and the general counsel for Anaconda. Maxie Anderson went on to be one of three men to first cross the Atlantic in a helium balloon in 1978). This video also shows how bertrandite it is mined today by Brush Engineered Materials using open pit mines, then transported and processed at the concentration plant near Delta, Utah. The concentrated beryllium hydroxide is then shipped by rail to Elmore, Ohio for final refining into beryllium metal, alloys, and ceramics products. This episode also discusses Chronic Beryllium Disease, the main health hazard of refining or working with beryllium.

Chronic Beryllium Disease:

Beryllium dust, when in the air in concentrations of greater than 2 micrograms per cubic meter, gets inhaled and irritates the lung alveoli. The body treats it as an invading body, and sends white blood cells which surround the beryllium particle and form small granules called granulomas in the lungs. At this point, a person is said to have sub-clinical CBD or is “sensitized” to beryllium. Most people who are sensitized do not develop clinical CBD, but in about 2-5% of sensitized people, the immune system overreacts and the granulomas build up to where the lungs become stiff and respiratory function is impaired, leading to symptoms similar to pneumonia. There is no cure once CBD has set in, and the eventual result is painful death.

Before the effects of beryllium dust were known, a high number of workers in the beryllium industry were getting sick, especially in certain plants such as the old Brush Wellman plant in Lorain, Ohio. Beryllium in its ores (beryl crystals and bertrandite) is tightly bound to the crystal lattice and is therefore harmless. But refining bertrandite or beryl means that the beryllium is physically and chemically separated from the crystal, resulting in fine beryllium particles getting into the air unless precautions are taken. The effects of beryllium disease were well enough known by the mid-1960s that when the Delta concentration plant was built, safeguards were put in place that reduce beryllium dust to under 0.2 micrograms per cubic meter of air, or less than 10% of the maximum safety levels. Workers also wear respiratory equipment such as facemasks with filters to prevent even that level of dust from entering their lungs. There has not been any incident of chronic beryllium disease in the workers at the Delta plant.

Final beryllium metal, alloys, and ceramics are also fairly safe as the beryllium is part of the metal and not airborne. The danger occurs when these materials are cut, machined, or milled, which allows beryllium particles to get into the air where they can be inhaled. The only way to cure chronic beryllium disease is to avoid it in the first place by preventing beryllium dust from entering the air. Special precautions must therefore be taken in any business that handles beryllium. OSHA has been studying CBD and is likely to be coming out with new and even stricter standards soon.

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Calderas of Juab County

Volcanic Calderas of Millard and Juab Counties, Utah

Usually, when one thinks of rocks and geology it’s all a bit impersonal; after all, they were formed in the distant past, in many cases hundreds of millions of years ago. Most of the rocks in western Utah, where I’m from, were laid down as ocean deposits during the Paleozoic Era. Now all the layers of shale, limestone, and dolomite have been thrusted, twisted, and even overturned, so that in some areas the Paleozoic rocks lie on top of younger Mesozoic rocks. How could this have happened? But in addition to these sedimentary rocks, there are some anomalies; whole mountains that puzzled me because they didn’t fit in. My grandfather, who lived next door to us in our small hometown of Deseret, would take me for drives out on the west desert looking for trilobites or pine nuts or just collecting rocks. One area we visited was Topaz Mountain at the southern end of the Thomas Range in Juab County, where one can find topazes just by walking along an arroyo on a sunny day, following the flashes of light. The rocks there are weird, with strange cavities and a light gray texture much different than the surrounding mountains. I wondered where it came from, how the topazes got there, how old the rocks were, and above all, how geologists were able to answer these questions.

Desert Mt. Pass

View from Desert Mt. Pass

This was all very interesting to me as a child, but then geology got personal. My father was a farmer and cattle rancher, and one day in June of 1971, we were hauling a load of yearling heifers out to our ranch in southern Tooele County (about 50 miles due north of Deseret). As we were driving our old 1952 model half-ton truck over the pass on Desert Mt., the brakes and clutch both failed at the same time and we found ourselves rolling down the steep and winding road without any means of stopping (the road has since been improved, as you can see at right. Back then the road cut along the left side of the pass and was much more dangerous). Dad tried to slow the truck down by ramming it into the embankment on his side, but the impact jarred the cab, flung open the door on my side, and threw me from the cab (this truck had no seat belts). Fortunately, there is a gap in my memory at that point for several seconds. The next thing I can remember is lying on my back looking at the truck as it rolled away from me and disappeared out of sight over the edge of the embankment. Then I saw my right leg, which was twisted unnaturally, with my thigh badly torn up – a whole piece of my thigh seemed to be missing, as far as I could see through the tattered remains of my pants. The best I can figure is that the rear dual tires of the truck rolled over my leg, breaking it in two places and tearing up the skin and underlying tissue badly. Or my leg dragged over the rough, sharp rhyolite rocks of the mountain. Or both.

Desert Mt. Rhyolite

Rhyolite formations at Desert Mt. Pass

This was a hot day in June. We had water and snacks, but my father had sprained his ankle and could not walk. This was before cell phones or even CB radios, and we had no way of getting help. You have to visit the west desert of Utah to appreciate just how isolated it is. Dad lit the truck on fire, hoping the column of smoke would attract attention from the ranchers (including my grandfather) across Ereksen Valley, but no one saw it. Hours dragged by. I was slowly bleeding to death as blood seeped out of my wound, and I was going into shock. After about five desperate hours, my father saw a car sitting on the road leading up to the pass; they had stopped when they came around the corner and saw the smoldering remains of our cattle truck. Dad stood up and waved, and they drove on up. The car was driven by a an elderly couple from Odgen, Utah: rockhounds who were out on the west desert looking for Topaz Mt. All they had was a hand-drawn, inaccurate map and they were off course by 40 miles. Dad was able to ride in to the nearest phone (about 15 miles) and call the ambulance and Doc Lyman from Delta. After several days in Intensive Care, two months in the hospital with skin grafts, and another three months in body casts, I was finally able to walk again. I am lucky to have two legs.

So my life was profoundly affected by the geology of Utah’s west desert. Desert Mt. almost killed me; Topaz Mt. saved my life. So I have understandably been curious about the geology of these two mountains. I can honestly say that I am a part of that geology – somewhere on Desert Mt. there’s a small patch of dirt that used to be me. And that geology is a part of me, too – the doctors were never able to get all of the small rock fragments out of my leg that had been ground in. Yes, I know it’s a bit grotesque, but it’s literally true.

That’s why I’ve wanted to complete these episodes on the beryllium deposits of western Utah before doing any others, because telling that story includes the story of the geology of the area and how those two unusual mountains came to be there in the first place. The episodes are coming along nicely, and I have completed the geology section completely and offer it now for your enjoyment. The first episode (on the sources, uses, and geology of beryllium) will be ready in a few days; the second episode on the mining, refining, and hazards of beryllium will be ready by next week.

Here is the script of this section, in case you’d like to read along with the video:

Geologic Origins of the Bertrandite Deposits in Western Utah

To understand the origins of the beryllium deposits in the Spor Mts. we have to go back to when western Utah was still under the ocean. For hundreds of millions of years, this ocean floor built up gradual layers of shale, limestone, and dolomite. The North American tectonic plate began to separate from the rest of Pangaea about 200 million years ago and was moving westward into the Farallon Plate, which was subducting under the western margin of North America. The sediments carried down with it were heated and rose toward the surface to cool as the granitic plutons of the Sierra Nevada Mts. For the first time, the western half of Utah and Nevada rose above the ocean.

Overhead View of Topaz Mt. Area

Aerial View of Topaz Mountain Area

Then, about 150 million years ago, the North American Plate sped up; instead of moving about 2.5 cm per year, it leaped ahead at the breakneck speed of about 8 cm per year. Instead of subducting, the remnants of the Farallon Plate were pushed under western North America, scraping and dragging the roots of the continent with it. This friction caused a wave of thrust faulting and mountain building to travel west to east across Nevada (the Nevadan Orogeny), then across western Utah (the Sevier Orogeny) about 125-75 million years ago. A huge mountain range rivaling today’s Rockies sat on the Utah-Nevada border, with sediments washing off of it into an inland sea to the east to form the upper layers of the Colorado Plateau as dinosaurs wandered through the mud flats and swamps. These swamps became the coal deposits of central and eastern Utah.

As the thrust faulting continued east, it encountered the thick Colorado Plateau and bent it into the huge anticline of the San Rafael Swell. When it reached Colorado and Wyoming about 55-60 million years ago, the thrust faulting created the Laramide Orogeny that resulted in the Rocky Mountains, including the Uinta Mountains of northeast Utah.

About 50 million years ago the North American Plate slowed down again and the remnants of the Farallon Plate collapsed from underneath, pealing away in a wave that now traveled from east to west. A wave of volcanism traveled with it, moving back across Utah and Nevada. Much of the mineralization found in Colorado, Utah, and Nevada occurred at this time, including the silver, copper, zinc, lead, and beryllium deposits of Utah. In western Utah, the volcanism produced several zones of Andesitic volcanoes with calderas and ash flows, including the Thomas-Drum Mt. caldera along with calderas at Keg Mt. and Desert Mt., about 45-39 million years ago and continued for at least 30 million years through several phases. In the first phase, quartz-rich magmas formed the calderas and ash flows that covered much of the area and produced the gold, copper, and manganese deposits of the Detroit District in the Drum Mts. The second phase of area volcanism occurred as the calderas in the Spor and Drum Mountains subsided and were filled with rhyolite from the Dugway Valley caldera about 38-32 million years ago.

Utah during Oligocene Epoch

Utah During Oligocene Epoch, 30-40 million years ago

The ancient thrust faults and collapsed calderas created fractures, which served as avenues to intrude veins of mineral-bearing magmas. Beginning about 25 million years ago, a third phase of volcanism pushed domes of highly alkaline rhyolite rich in fluorine and beryllium up through these fractures. The fluorine and beryllium minerals formed gases that were injected into the thrust faults and eventually encountered ground water, which flashed into steam, shattering the surrounding rhyolite and forcing the beryllium minerals to precipitate throughout the fractures and empty spaces in the host rhyolite rocks. Gradually, minerals were deposited as crystals of topaz, fluorspar, garnet, and bertrandite in the Thomas-Spor Ranges, and red beryl in the Wah Wah Mts. Additional trace elements such as uranium, lithium, aluminum, zirconium, iron, and thorium were also deposited.

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The next videos that will be completed for the Elements Unearthed Project are two episodes on the sources, mining, refining, and uses of beryllium. I’ve written a few posts previously about this topic, and as I continue to organize and prepare materials to use in the videos (which will be edited over the next week), I have created several diagrams that describe the process used for surveying and developing open pit mines at the Brush Resources’ Spor Mt. mine site in western Utah. You might say, “Beryllium? Why should I care about some rare metal that I’ll never use in my lifetime?” But you’d be surprised. You are already using beryllium (for example, the electrical contacts inside the automatic windows of your car use a beryllium-copper alloy because it can handle frequent changes in heat and resists corrosion better than many other alloys). Beryllium is also an essential metal for medical, nuclear power, and aerospace applications. I’ll discuss more of beryllium’s uses and its refining and sources in a later post, but in this post let’s talk about how the bertrandite ore is mined.

Spor Mt. beryllium deposits

Location of Bertrandite in Western Utah

Mining Operations at Brush Resources

The bertrandite ore found in the Spor Mts. is very similar to clay (an aluminum silicate) and looks like common dirt except it has a slight pinkish color. It’s also associated with fluorspar or fluorite, which is often a deep blue to violet color. One is tempted to think the more colorful fluorite is the mineral we want, but it’s actually the crumbly pink coating found on the fluorite nodules. Elsewhere in the Spor Mts., the fluorite has been mined commercially.

The first attempt at mining the bertrandite ore was started by Anaconda on their claim. They tried hard rock mining, but the soft altered rhyolite of the ore body proved too dangerous to mine that way.  One day, while the miners were all having lunch, the mine caved in. Fortunately no one was hurt, but it was determined then that the only safe method was open pit mining.

Exploratory drilling

Exploratory core drilling

Potential mine sites are surveyed by drilling core samples every 100 feet to map out the general location of the ore bodies. The bertrandite deposits in the Spor Mts. are located in a mineralized zone of altered rhyolite tuff that overlies a bedrock of limestone. This soft and crumbly altered layer is overlaid by a tough, hard layer of unaltered rhyolite with about the same composition and hardness of granite. All of this is further overlaid by a layer of gravel, loose rock, and sand deposited by Lake Bonneville during the last ice age. Since the ore body is tilted, it occasionally reaches the surface (where it was originally discovered) and in other places dips so far below ground as to be unfeasible to mine. Several mine sites, such as the Blue Chalk and Roadside I sites have already been mined, but enough reserves have been mapped to last at least 50 more years at current production levels.

Planning an Open Pit Mine

Planning an Open Pit Mine

Once the location of the ore body has been generally mapped out, mining engineers plan out an open pit structure that will reach the ore with the least disturbance to the overlying layers while keeping the sides of the pit terraced to safely prevent rockslides and excessive erosion. Once the plan is approved, a contractor is hired to remove the overburden, usually in the winter and spring months. The loose alluvial gravel and soil is removed first and set aside for later reclamation. The hard rhyolite is blasted and removed, and the altered rhyolite layer is also removed to within about seven feet of the bertrandite ore.

Removing the Overburden

Removing the Overburden

A second phase of core drilling is carried out, with holes every 25 feet to more accurately map out the exact ore locations. For a typical ore body, between 40 and 60,000 cores are drilled and sampled every two feet. 3D structural maps are prepared to identify where various grades of ore are located. The ore is then removed carefully; a technician with a portable field berylometer walks before the bulldozer and stakes out the locations of the ore grades that are being removed; a self-loading scraper scoops up the ore and moves it to stockpiles where it is sorted by grade into the same pile. The ore is then transported by 18-wheeler to the processing plant near Delta, Utah, about 50 miles southeast. High-grade ore is mixed with low-grade ore so that all the bertrandite coming to the plant has about the same percentage of beryllium. The final ore has less than .65% beryllium, or about four pounds per ton.

Next Post: Refining Beryllium Ore

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