Rock And Gem - November 2005 - Feature Article

Thanks to the rapid growth in cultural tourism that emphasizes regional historical attractions and activities, "tourist mines" are riding a wave of popularity. Across the United States, some 50
mines now pay their way not by extracting and shipping ores, but by offering tours to the public. Most are former gold mines, which is not surprising considering the yellow metal's appeal, romance, and rich history. But to a lesser extent, mines that once produced silver, copper, lead, and coal also serve as tourist mines.

And now, one of the nation's newest tourist mines, the Lost Mine, near Salida in central Colorado, showcases a less-familiar mineral commodity: manganese. The Lost Mine may be the only underground manganese mine ever to re-open as a tourist attraction. But manganese is not all that sets the Lost Mine apart. Unlike most tourist mines that visitors can drive to directly, the Lost Mine is hidden away in rugged backcountry; getting there is an adventure in itself. Furthermore, the Lost Mine, which operated only during World War I, represents an obscure period in American mining history, one that falls between the precious-metal mining of frontier times and the modern mining era.

The story of the Lost Mine begins with manganese itself. Manganese oxides and oxyhydroxides-the Lost Mine's ore minerals-have been used as black pigments since antiquity. But because manganese, a silverywhite, brittle metal about as dense as iron, does not occur in native form, it was not isolated and identified as an element until 1774. The first important modern use of manganese compounds came in the 1860s with the development of the dry-cell, carbon-cathode battery (the modern flashlight battery). Manganese dioxide is a vital component of the electrolytic paste that separates the battery's carbon cathode from its zinc-cased anode.

Nineteenth-century researchers also learned that manganese was an excellent flux for deoxidizing iron and steel in reduction processes. And by 1900, metallurgists had found that adding manganese to steel created a tough alloy with great resistance to mechanical wear.

Despite these developments, however, industrial demand for manganese and other alloying metals such as tungsten and molybdenum remained limited, and commensurately low prices gave prospectors and exploration geologists little reason to search for the metals.

But this all changed abruptly in 1914 with the outbreak of World War I. Soaring demand for hard, durable steel alloys for weaponry and armor and for the tool steels needed for their fabrication quickly drove the prices of manganese and other alloying metals to record levels. As manganese prices quadrupled, prospectors once concerned only with gold and silver now began searching for deposits of this formerly obscure alloying metal.

Among them was W. H. Boyer, who supervised a lime-kiln operation near the railroad stop of Wellsville, six miles east of Salida. In his spare time, Boyer prospected the interbedded strata of sandstone, shale, limestone, and travertine that were exposed in the nearby ridges and canyons. His efforts were rewarded in January 1916, when he discovered an outcrop of pyrolusite, psilomelane and wad.

Pyrolusite, or manganese dioxide, the primary ore of manganese and the most common manganese mineral, occurs in black or dark bluish-gray powdery, granular and fibrous masses and as dendritic crusts. Psilomelane, a complex barium manganese oxyhydroxide of variable composition (and thus not a valid mineral species), is a lesser ore of manganese. It is black, earthy and brittle, and forms fine-grained, botryoidal crusts, stalactites, and cavity fillings. Wad, a generic term, refers to a variable mixture of oxides and hydroxides of manganese and barium. Pyrolusite is a secondary mineral that, along with psilomelane and wad, sometimes forms replacement deposits in limestone.

What Boyer had discovered was an outcrop of a replacement deposit in which pyrolusite, psilomelane, wad, calcite, and dolomite had replaced a limestone bed. His shallow open cut revealed the approximate size of the deposit and the fact that it dipped at an angle of roughly 45 degrees. After assays indicated that the pyrolusite contained 40 percent manganese by weight, Boyer immediately I staked two lode claims.

Boyer brought samples and assay reports to the Colorado Fuel I & Iron (CF&I) steel mill at Pueblo, 90 miles to the east. Metallurgical tests showed that the pyrolusite could be used directly that is, without any prior milling, concentration or refining-as both a deoxidizing flux and as a source of alloying manganese. The steel company offered Boyer a contract to purchase at the going market price all the hand-cobbed pyrolusite ore he could provide. After some exploratory tunnel
ing, Boyer estimated that some 5,000 tons of pyrolusite ore were waiting to be mined. He hired a few local miners to construct a portal at a lower point on the hillside and begin driving a haulage tunnel to intersect the deposit. The reasonably stable rock required only minimal timbering for ground support. And by driving the haulage drift beneath the dipping ore bed, miners could extract ore from overhead stopes. In this simple, inexpensive mining approach, the ore would fall by gravity to the haulage level to be loaded into small ore cars.

With miners using only hammers and hand steels for drilling, mine development proceeded slowly. But that was no concern for Boyer. A few months later, he accepted a $25,000 offer for his claims and made a profitable exit from the manganese-mining business. As the new owners continued to develop the mine, they also conducted additional assays which revealed that some pyrolusite ore contained as much as 3 percent tungsten. Tungsten, which increases both hardness and thermal resistance of steel alloys, is rarer than manganese and much more valuable, especially since wartime demand had increased its price tenfold. That made a single ton of the best ore, which contained 40 percent manganese and 3 percent tungsten, worth about $350. It also sent prospectors on a lively, albeit nonproductive, tungsten "rush" into the nearby hills.

The mine made its first small shipment in 1916. After extracting ore from a single stope, miners hand cobbed it at the portal, an easy job because pyrolusite's distinctive black color readily distinguished it from gangue rock. After screening and sacking the ore, they loaded it into a wooden sled inside a makeshift declined conveyer, a long, enclosed metal chute that led to a lower loading tipple fashioned from rough logs. From there, mule drawn wagons hauled the ore two miles to the railroad at Wellsville for shipment to the CF&I steel mill.

The mine made another shipment of ore, this time 40 tons, in 1917. But during its brief operating life, the mine shipped only a total of 80 tons of ore. Plans for higher production were cut short when World War I came to an end with the Armistice of November 11, 1918. Almost overnight, demand for alloying metals fell flat. Prices for manganese and tungsten plummeted, and the mine closed in early 1919. During the following decades, only a few backcountry hikers visited the mine. Even its location became confused when a realignment of the nearby county line "moved" it from Fremont County into Chaffee County. Since Fremont County had "lost" the mine, it became known among local residents as the Lost Mine.

The mine remained largely forgotten until just a few years ago, when Salida rockhound and builder/developer Monty Holmes began looking for backcountry property for a cabin site. He came across the old mine and conducted an initial underground exploration using light from improvised sagebrush torches.

"I returned later with better lighting and found an ore car, haulage rail, some blasting materials, and even some old ceramic whiskey jugs that the miners had left behind," Holmes recalls. "There were three interior drifts, two tunnels, and a stope-about 150 feet of underground workings along with some well-preserved square-set timbering. After researching the history and geology, I bought the property and started thinking about turning the mine into a tourist attraction."

But first, Holmes had to do a lot of work.

"The mine had been inactive for 85 years, and much rock had sloughed off the ribs and the back," Holmes explains. "In places it was 3 feet deep, and it all had to be removed."

Holmes hired three retired miners from a pair of well-known Colorado mines, the Climax molybdenum mine and ASARCO's Black Cloud Mine, both about 50 miles north of Salida, near Leadville. They cleaned out the waste rock, checked the timbering, installed a few timber stulls for additional groundsupport safety, and rigged an underground lighting system.

"When things were ready, I requested an inspection by the Colorado Division of Mines," Holmes recalls. "A state inspector checked everything from oxygen levels to rock stability and approved the mine for public tours."

Because the mine is inaccessible by highway vehicles, Holmes needed one more thing-a reliable, rugged, and roomy vehicle capable of transporting more than a dozen visitors at a time to the mine. His choice was a Pinzgauer, a 14-passenger truck manufactured in Austria by Steyr Daimler Puch for several European military forces. This rugged, six-wheel-drive vehicle would prove ideal on the rough Lost Mine tour route, where one backcountry grade actually measures a rollercoasterlike 50 degrees.

The Lost Mine tour begins in Salida, where visitors board the Pinzgauer "Minemobile" for a six-mile journey east along U.S. Highway 50, past the Wellsville Fold and adjacent geological faults, and into the Arkansas River canyon. At Wellsville, the tour turns off onto dirt roads that lead to its first stop, the lime quarry and kilns that Boyer supervised at the time he made his manganese discovery in 1916.

Nestled near the base of a colorful, iron-stained limestone cliff, the kilns, which date to 1895, originally had circular brick walls 25 feet high, with spaced holes for regulating the draft and bottom gates for removing finished lime. Quarrymen blasted limestone from the cliff, crushed it into fist-sized chunks, then loaded it into the kilns, alternating layers of limestone (primarily calcium carbonate) with layers of pinon-wood fuel.

In a calcining reaction, heat broke down the calcium carbonate molecules, driving off carbon dioxide to leave behind calcium oxide, or lime (quicklime). The addition of water converted the quicklime to calcium hydroxide (caustic lime). In the early 1900s, quicklime and caustic lime found use in everything from plaster, mortar, stucco, and whitewash to septic treatments and soil conditioners. The quarry and the kilns operated until 1935, when mass-produced cement mortar largely replaced lime mortar.

Back in the Minemobile, Holmes explains points of geological and mineralogical interest, including several visible geologic faults. As an example of faultzone rock, Holmes passes around a superb specimen of "slickensides," a rock which fault movement had naturally polished to smoothness and luster. When the Minemobile nears an old quarry that produced travertine, a massive, layered calcium carbonate (aragonite or calcite) rock of hot-springs origin widely used as a building stone, it passes around a gleaming slab of cut and polished pink travertine.

The last mile of the trip is fairly steep and ends at the Lost Mine itself, elevation 7,700 feet. As visitors enjoy the view to the south that takes in the Sangre de Cristo Mountains and 14,345-foot-high Blanca Peak 70 miles distant, Holmes fires up the portable generator that powers his underground lighting system.

Leading his tour group along the 50 yard-long path to the mine portal, Holmes points out W. H. Boyer's original, 90-year-old discovery cut. At the mine portal, he displays a collection of pyrolusite and psilomelane specimens, most associated with white calcite and dolomite in a variety of interesting habits. While visitors examine the specimens, Holmes enters the mine alone to measure oxygen levels, check the electric lighting, and to look for any potential safety hazards.

After providing everyone with a flashlight and a required hard hat, Holmes leads the way into the mine, pausing at the original square-set timbering to answer questions about ground support. He then continues on to a spacious, open area beneath a high stope, where the rock walls show a massive, jet-black vein of pyrolusite and psilomelane decorated with snow-white crusts of calcite and dolomite, Holmes describes how miners extracted ore from the overhead stope using hand drilling methods, then loaded it into ore cars for hand tramming to the portal.

Because visitors are literally standing in the middle of the manganese deposit, Holmes' explanation of its genesis is easy to visualize. The surrounding country rock is of marine origin with alternating beds of sandstone, shale, and 300 millionyear-old late Paleozoic limestone. Later, hot solutions would dissolve manganese minerals from adjacent formations, transporting them to a section of the limestone bedding that served as a solution trap.

After the solutions dissolved away parts of the limestone, manganese minerals precipitated out of solution and filled the resulting voids. Secondary calcareous solutions then circulated through the manganese mineralization to deposit calcite and dolomite. The manganese deposits irregularly follow the original limestone bedding, pinching and swelling in places to create massive ore pockets.

Holmes explains that the ore consists mainly of pyrolusite and psilomelane, with lesser amounts of wad and manganite (manganese oxyhydroxide). In places, the ore body is crystalline and fibrous, with numerous cavities containing botryoidal psilomelane. The cavity walls often consist of alternating bands of compact psilomelane and fibrous, crystalline pyrolusite. Also apparent are many rod like growths and concretions with hard outer shells of psilomelane encasing pyrolusite.

Holmes then treats everyone to a display of underground color. Cutting the lights and plunging the mine into darkness, he demonstrates with both longwave and short-wave ultraviolet lamps how mineral impurities create a white and green fluorescence in some of the calcite and dolomite.

When the underground tour concludes, visitors board the Minemobile for the return trip to Salida. Salida is 90 miles west of the city of Pueblo via U.S. Highway 50 and 140 miles southwest of Denver via U.S. Highway 285. The Lost Mine tour departs from the Country Bounty, one of Salida's most popular restaurants, on U.S. Highway 50, From May through October, tours leave daily at 10 a.m. and 2 p.m. Monty Holmes personally guides each of the three-hour tours. Walk-ins are welcome, space permitting, but reservations are always recommended. From November through April, tours must be arranged in advance. The cost of the tour is $39 for adults and $29 for children ages 12 and under, and includes transportation in the Pinzgauer Minemobile.

Because of the relatively high mine elevation (7,700 feet) and rugged terrain, visitors should be in good physical condition and wear sturdy hiking shoes. Even in summer, light jackets are recommended for comfort, as the interior mine temperature hovers at about 50 degrees F year 'round.

For reservations or further information, call (719) 221-MINE (6463) or visit the Web site www.salida.com/lostmine.

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