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Posts Tagged ‘mammoth utah’

For the last week, I’ve been busy preparing for my classes at Walden School, including inventorying the science lab room (which is also my classroom) and planning out my course schedules. I’ll be teaching two sections of Chemistry, one of Astronomy, one of Computer Technology (a basic computer literacy course required in Utah), a section of Media Design, and a section of Video Production. This is, for me, a perfect schedule. In the meantime I’ve also been preparing a series of maps and 3D images of the Tintic Mining District, focusing on the ore deposits and the various mines located there. I’ve also prepared the script for this section of the video, which I have pasted below:

Mines in the East Tintic Mts

MInes and Roads in the East Tintic Mtns.

Tintic Geology

To understand how the ore bodies in the Tintic District were deposited, we have to start about 800 million years ago in the Precambrian Period when the western portion of the North American craton rifted away from the rest of the continent along a line where the Wasatch Front now lies – this Wasatch Line has been an important hinge line in Utah’s geology ever since. For the next 600 million years, a sequence of ocean sediments including dolomite, limestone, shale, and sandstone were deposited off the coast in the geosyncline that would become western Utah. Beginning 150 million years ago, Nevada and then western Utah were uplifted as the Farallon tectonic plate was pushed under North America. Like a throw rug being wrinkled up as it’s pushed over a hardwood floor, western Utah was folded by thrust faults into a large mountain range during the Sevier orogeny about 70 million years ago. This thrusting continued across eastern Utah and into Colorado and Wyoming during the Laramide orogeny, building up the Uintah and Rocky Mountains.

East Tintic Mines

Mines in the eastern portion of the Tintic Mining District

Then, about 50 million years ago, the Farallon plate began to collapse from underneath the continent. As it peeled away, a wave of volcanism moved from east to west across Colorado and Utah. Intrusive laccoliths rose to the surface, bulging up the LaSal and Henry Mountains in eastern Utah and forming explosive calderas in several places in western Utah. About 35 million years ago, a series of calderas formed in the area that would become the Tintic Mountains. A large andesitic volcano rose up from eruptions of ash and tuft.

Tintic Standard ore samples

Ore samples from the Tintic Standard Mine, eastern district.

About 31.5 million years ago, the volcano collapsed as the intrusive magma began to cool. Mineral rich fluids were injected into the surrounding limestone, quartzite, and dolomite as replacement beds. The hot magma caused the carbonate rocks to decompose; for example, limestone turns into lime or calcium oxide and carbon dioxide gas when heated. This left large cavities that then filled up with the mineral-laden magmas. These deposits are called stopes, such as the famous Oklahoma stope of the Chief Consolidated mine. The carbon dioxide released from the decomposing limestone and dolomite in turn dissolved into the hot magma, making it a kind of lava champagne, and reacting with it to form various exotic minerals, some of which are found nowhere else.

More Tintic ore samples

More ore samples from the Tintic District

The primary ore-bearing minerals in the Tintic District are enargite, tetrahedrite, galena, sphalerite, pyrite, marcasite, and native gold, silver, and copper. But many more minerals are present, including unusual minerals that blend copper, silver, tellurium, arsenic, sulfur, carbonates, hydrodixes, etc. At the Centennial Eureka mine, over 85 different minerals have been identified, ranging from common pyrite, malachite, and azurite to minerals found only here. It is the type locality (where the mineral was first identified) for leisingite, frankhawthorneite, jensenite, juabite, utahite, and eurekadumpite. Other rare minerals include xocomecatlite, carmenite, adamite, duftite, and mcalpineite.

These mineral deposits occurred around the edges of the caldera and formed the five large ore zones of the main Tintic District. The Gemini Ore Zone runs to the west of Eureka south to the north edge of Mammoth Gulch. The Gemini, the Bullion Beck and Champion, the Eureka Hill, and the Centennial Eureka mines (known collectively as the Big Four) are located on this zone.

The Chief-Mammoth Ore Zone begins under the center of Eureka and extends due south across the mountain to the east end of Mammoth Gulch. The Chief Consolidated mine is located on the richest ore body, which is right under the center of Eureka city; up the hill is the Eagle and Blue Bell mine, named for the beautiful deposits of azurite found inside. Further south over the top of Eureka Peak lie the Grand Central, Mammoth, Apex, and Gold Chain mines that are also part of this deposit.

Ore zones in the Tintic District

Ore Zones and Major Mines of the Tintic Mining District

The Plutus Zone branches off of the Chief-Mammoth Zone high up in the Tintic Mountains. The Godiva Zone starts just east of Eureka and runs southeast in a curve where it joins the Iron Blossom Zone, which continues in a curve south and then southwest. Some mines in these zones include the Godiva, May Day, Humbug, Beck Tunnel, Sioux, and Iron Blossom mines.

In the eastern section of the Tintic District, several zones of minerals were deposited and were among the last to be discovered because they are overlain by 400 feet of igneous rock. These bodies include the Burgin ore body, the Tintic Standard, and the North Lily bodies. Other bodies are located at the Apex and Trixie mines.

In the southern section of the Tintic District, the large replacement bodies give way to smaller fissure veins that are only two feet wide on average but can be up to 4000 feet long. Here, the mineral-bearing magma was injected into cracks and fault lines already existing in the host rocks. The Dragon mine is the only true open pit mine in the area; it sits on top of a network of fissure veins at the south end of the Iron Blossom Zone. Other mines in the area include the Swansea and Sunbeam mines at Silver City, the Tesora and Treasure Hill mines at Ruby Gulch, and the Showers mine at Diamond Gulch.

More ore samples from the Tintic Standard Mine

More ore samples from the Tintic Standard Mine

The final chapter in the area’s geomorphology began about 17 million years ago when normal faulting created the Basin and Range province, lifting up blocks to form the mountain ranges of Utah and Nevada, including the East Tintic Mountains. Other blocks sank to form the valleys, such as the Tintic Valley. Erosion has exposed the ore bodies in many places, including the outcropping that George Rust stumbled over in 1869. It was to become the Sunbeam Mine.

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Loading chute at Dividend Utah

Ruins at Dividend, Utah

The last few weeks I’ve had to neglect the Elements Unearthed project in order to finish a client video that had a tight deadline. It was uploaded to YouTube Thursday night, so I now have a little bit of a breather before the next project and am back at work on Part 2 of the beryllium video. Winter has finally decided to let go (after one last gasp – we had a snowstorm here just two weeks ago), and already the early summer heat is drying out the cheat grass and turning it a brownish-purple color on the lower south-facing slopes. I decided now was the time to do some exploring and photography while the grass is still green in the mountains.

Belt wheels and Mt. Nebo

Belt Wheels and Mt. Nebo

Over the last two years I’ve visited the Tintic Mining District several times with students and my own children and have collected a considerable amount of photos and video clips, including a tour of the Tintic Mining Museum and an interview with June McNulty, who runs the museum with his wife. But there were several places in the district that I hadn’t visited, including Mammoth and Silver City. So yesterday (Friday, June 4) I packed up the cameras and headed for the hills.

Glory hole at Dividend

Glory hole at Dividend, Utah

Change room stove at Dividend

Change room and stove at Dividend, Utah

I stopped first in the hills above Burgin, the site of the town of Dividend, so called because the mine paid out fairly decent dividends to the miners compared with other mines in the district. I decided to climb up the hill further than before, toward the two large rusty tanks that can be seen from the road. I was surprised to find much more there than I had known about before, including the ruins of miner’s houses (some semi-wild purple irises and lilacs were still alive and blooming). A processing plant once existed here, and the ground is covered with yellowish-stained rocks and pieces of slag and everything smells of sulfides. One ruin 2/3 up the hill still has an old rusted stove for keeping the miners warm in what was probably the change room – the mine portal itself is just above the room, and there are even a few remains of timecards used to clock in and out of the mine. The few I looked at were dated from 1971, which was about the time that the mine at Dividend finally closed down. Mining continued, periodically, further down the slope at Burgin. Almost forty years of weather has taken its toll; all the roofs and any other wooden structures have long since rotted away, leaving old, dry fragments of boards with rusted nails sticking out littering the ground. Most of the equipment is gone, taken by looters and souvenir hunters, but enough of the foundations and structures remain that one can imagine what Dividend looked like in its heyday.

Wild irises at Dividend

Wild irises at Dividend, Utah

The road past Dividend is off the main path of Highway 6. It’s a good road, well maintained and asphalted but not much visited. I only saw two other cars and a motorcycle during the four hours I spent exploring along the road. The East Tintic Mountains between Dividend and Eureka are dotted with old mining ruins and tailings piles, with dirt roads leading off frequently up every side canyon and ridgeline. Most of the area is posted No Trespassing, so I limited myself to taking photos from the main road. It is still late spring up there; the maple trees in the canyons have only just gotten their leaves, and wildflowers including mountain lupine and Indian paintbrush cover the hillsides.

Indian paintbrush

Indian paintbrush near Eureka, Utah

Blue Lupine

Blue Lupine near Eureka, Utah

I traveled through Eureka and saw the continuing cleanup efforts there (more on this in my next post) and drove on to the town of Mammoth. Located in a side box canyon just to the south of Eureka, this was one of the richest areas of the Tintic Mining District. The mines are located ringing the valley – many long since abandoned but several showing recent work. With prices for gold and silver high right now, much exploration is underway to re-work the old claims and tailings piles and to do new exploratory drilling. Again, most of the area is posted and is private property; I limited myself to the main streets of Mammoth to photograph the old buildings and mine dumps.

Mine at Mammoth Utah

Mine at Mammoth, Utah

At one time, when the processing plant was in full operation in the early 1900s, Mammoth boasted a population of about 2000. The people lived in the upper eastern portion of the canyon (Upper Mammoth) while the mill was at the mouth of the canyon lower down the slope (called Robinson after the mill’s foreman and later Lower Mammoth). Once the town was incorporated, public works such as churches and even a hospital (rare for a mining town) were built in the middle, or Midtown. In the early 1930s, my father used to visit his first cousin Ralph Larsen, whose family lived in Mammoth. During the winter the road leading up to town would be covered in packed snow, and the two of them would ride their sleds from Upper Mammoth all the way down to Highway 6, almost two miles, without ever stopping. Then they’d have to wait for someone to give them a lift back to the top.

Miner's shack in Mammoth Utah

Miner's Shack in Mammoth, Utah

Even though the mines had all closed by the 1950s, Mammoth somehow escaped the fate of most boom-and-bust mining towns; it never completely died. A few people hung on. Over the last ten years, since I last drove up here, it even appears to have grown in population. More houses have been fixed up and are occupied than before, and it is becoming an artistic community of sorts. Renewed interest in mining has also given the town a boost.

Lizard

Lizard in the ruins at Dividend, Utah

After Mammoth, I visited the old Jesse Knight smelter at Silver City and drove up the canyon there, but I’ll leave that for next time.

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