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Howardsville

Howardsville, Colorado on the Animas River.

So far on my tour through Colorado’s mining history, I have reported on how the ore was mined. Today, I got the chance to see how the ore was transported and processed at a mill. After completing my tour of the Old Hundred Mine near Silverton, I drove back down Stony Creek to where it joins the Animas River at a place called Howardsville, where some mining operations were still evident.

Arrastra Gulch

Google Earth view of Arrastra Gulch and Silver Lake. The Mayflower Mill is located at the bottom of the gulch in the upper left corner.

I stopped along the way toward Silverton at the base of Arrastra Gulch. This is the location of the main mining area around Silverton and one of the richest deposits in all of the San Juan Mountains. Before a proper mill could be built to process the ores, a Spanish-style arrastra was built here, which is a circular area with a flat stone floor and a central post with arms coming out. Each arm had a heavy stone or iron weight that hung from it and which would drag over the ore and crush it. Mules, donkeys, or even humans would be used to push the arms around in a circle. Once mills were built, the ore was transported to them from Arrastra Gulch and the high glacial circque above it (around Silver Lake) by tramlines or flumes. At one point as many as four separate overlapping trams were operating.

Arrastra Gulch marker panel a

Arrastra Gulch marker Part 1

The largest mill in the area was the Mayflower Mill (also known as the Shenandoah-Dives Mill) about two miles northeast of town. It was built in 1929 to process gold, silver, zinc, lead, and copper ores. Another large mill nearby was the Silver Lake Mill on the Animas River.

arrastra trams

Map of aerial trams in Arrastra Gulch near Silverton, Colorado.

Built of pre-framed Oregon fir and completed in six months for $373,000, the Mayflower Mill began processing ore in Feb., 1930 and continued in operation for 49 of the next 61 years, finally closing down in 1991. It is in fact still capable of operation, and all the original equipment is intact. The historical society allows self-guided tours that start in the machine shop, then move to the tram station, ore storage bins, ball mills, flotation cells, recovery system, assay office, etc.

Arrastra

A restored arrastra in Groveland, California. Heavy rocks were dragged around in a circle to crush ore.

It was an extensive operation, the biggest in the San Juan Mountains, and employed the latest technologies available in 1929, including the new techniques of ball mill crushers, froth flotation of sulfide ores, and recovery of base metals as well as gold and silver. These techniques are still used today in such places as the concentration plant at Utah’s Rio Tinto/Kennecott Copper operation, although the scale there is enormous.

Shenandoah-Dives mine

A sketch showing what the Shenandoah-Dives mine looked like during the 1930s. The aerial tramline connected with the Mayflower Mill.

For its 61 years of operation, it processed over 9,700,500 tons of ore to produce 1,940,100 ounces of gold, 30,000,000 ounces of silver, and over 1,000,000 tons of base metals.

Tramway in Arrastra Gulch

The aerial tramline connecting the Shenandoah-Dives Mine above Arrastra Gulch with the Mayflower Mill. The gulch is the canyon in the foreground, and the high circque is the basin around Silver Lake.

I used my camcorder to create a complete walkthrough of the mill, going in order from start to finish. At each stop I would stop the tape and take photos as well, and took my time to document everything. There were interpretive signs at each stop explaining what each piece of equipment did. Here is a rundown:

Mayflower Mill

The Mayflower Mill near Silverton, Colorado. A self-guided tour is available during the summer.

Processing Ore

The ore coming from the mines was about 5% metals and 95% waste rock (tailings). The metals have to be separated out, and this is done in stages so that all the metals (gold, silver, copper, lead, and zinc – the big five) could be individually removed and purified. This is done in three main steps: crushing, separation or reduction, and purification. The final step was done by a smelter off-site, but the first two steps were done at the mill.

tram station

Tram station at the Mayflower Mill. Full buckets descended from the mine by gravity, which also pulled the empty buckets back up.

The ore arrived in large open buckets by tramline. Gravity brought the ore down and allowed the empty buckets to move back up the loop. The ore was brought into the mill at the tram station and dumped, then transported by conveyor belt to the cone crushers. It was screened for size, and if too big would be returned to the crushers.

cone crusher

Cone crusher at the Mayflower Mill. It would crush the ore between rotating cones until it was pebble sized.

Once it was pebble sized, it would be transported to the Fine Ore Bin, which would hold 1200 tons of ore, enough for one full day of operation. The ore was then transported out of the bottom of the bin and mixed with water to form a slurry, then passed through a rod mill (which used long iron rods rolling around) where the ore was further crushed to a fine powder and sorted by a spiral classifier, an auger-like device that pushed the ore upward. If the ore was fine enough, it was pushed all the way to the top – if not, it would fall back down and be returned to the rod mill for further crushing.

rod mill

Rod mill at Mayflower Mill. Iron rods were fed into the mill, then allowed to roll around inside to crush the ore to the size of sand grains.

The powder, now the consistency of sand, was passed through a ball mill, with 2-3 inch diameter iron balls rolling around to crush the ore even finer. These balls were added frequently during the day through pipes from a ball bin. Now the ore was now the consistency of talc and fine enough to start to separate.

Spiral classifier

Spiral classifier at the Mayflower Mill. Ore slurry from the rod mill would be pushed up the spiral. If it was fine enough, it would be pushed over the top. If not, it would return to the rod mill.

The first metal to be separated was gold, using a system of settling jigs that pumped the ore through, allowing the heavier gold particles to settle out through vibration and suction. The lighter remaining material was passed on to flotation cells, where reagents and flocculents were added that would float the desired metals to the top of the tank solution while depressing or sinking the other metals. Lead was removed first, then copper, and finally silver and zinc removed in large tanks. The soapy bubbles would simply be skimmed off the top of the cells.

Ball mill

Ball mill at the Mayflower Mill. Ore crushed to the size of sand grains would enter the rotating drum and be crushed to powder by 2-3 inch iron balls.

The flotation cell solutions were then passed through filters with pumps that pushed the water through, drying out the solution to a damp cake-like material that was then shipped to a smelter for final refining, where it would be heated to drive off the sulfides. Each day, samples were removed and filtered through a squeeze press, then sent away to an assayer to determine the percentage of metals in each day’s run.

gold jigs

Gold jigs at the Mayflower Mill. Using air pressure, the lighter ore powder was suctioned away from the heavier gold particles.

Meanwhile, the gold filtered out by the jigs was sent through a concentration process. It would be passed over a shaking Deister table where the gold would be caught by riffles and formed a streak to be collected. It was mixed or amalgamated with mercury to remove the gold from the remaining waste ore. The amalgam was then formed into rounded boats or cakes and heated in a retort at 1200 ° F for 12 hours to evaporate the mercury, which was bubbled through water to condense it for reuse. The remaining gold was now called “sponge” and was about 80% pure. It would be sent off to a foundery for final purification. Four to five sponges would be produced each week. Each sponge weighed about 22 pounds. During the last year of the  mill’s operation (1991), a new process was developed that eliminated the need for mercury (which was highly toxic).

Lead cleaner cells

Lead flotation tanks at the Mayflower Mill. Reagents were added that would float the various metals, such as copper or lead, to the top of the liquid on soap bubbles which were skimmed off into the trough in front. The remaining metals were depressed to the bottom. Impellers would keep the solution agitated while blowing air through it.

Once processed, the waste material is called tailings and was made up of water and sandy ground rock. It was pumped down to settling ponds, where the solid tailings would settle out. This was an innovation of the Mayflower Mill, as previously the tailings would simply be allowed to flow into the Animas River. The high sulfur and iron content in the tailings would travel down the river and created the reddish stains on the rocks that I noted on my train trip up the gorge several days ago. At the Mayflower Mill, the ponds were shifted so that the solid tailings would build up a series of mounds downhill from the mill. These have now been collected into a large tailings pile near the mill.

Deister table

Deister table at the Mayflower Mill. It would shake, causing the gold particles to separate out against the riffles.

I found this self-guided tour to be fascinating from a chemistry perspective. The mill used a system of physical separations to crush, concentrate, and amalgamate the ore. The final smelting used a system of chemical separations. It is a perfect example of a chemical engineering process, and was continually upgraded and improved during its 61 years in operation. The mill could be run, during the night shift, with only three people. During the day there were additional people to do repairs and take samples, to run the gold process, and to run the machine shop. Shift supervisors oversaw the operation from the dog house, one man ran the crusher facility, and one man ran the flotation cells. This was the biggest operation of its kind in southwest Colorado and processed more ore than any other mill in the area.

gold sponge

A model of what gold sponge looked like after being removed from the retort furnace. The holes in it are caused by mercury vapor bubbling out.

Retort furnace

Retort furnace and gold button mold at the Mayflower Mill. The gold particles would be amalgamated with mercury, then heated in this retort furnace to drive the mercury off.

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red mountain reflection

The Red Mountains near Ouray, Colorado.

My original plans for this fifth day in Colorado’s mining towns was to drive north on Highway 550 to Montrose, then east on U. S. 50 and south on Highway 149 to Lake City and eventually Creede. But having to detour two days ago to Farmington, New Mexico to pick up a used rim for my minivan made it necessary to drive through Silverton without stopping. I did some quick calculating and found an alternate route that would allow me to hit all three places (but it would mean missing Alamosa and Great Sand Dunes National Park and having a very long day tomorrow). Since my trip is mostly about the history of mining in Colorado, I chose to take the alternate route. Alamosa will have to wait for another trip.

I packed up and ate some doughnuts and other supplies I had that were still good. The ice in my coolers had long since melted and things were beginning to go bad. I videotaped some panoramic shots along Ouray’s main street and talked for a few minutes with a Native American wearing a veteran’s hat, whom I had seen around town. He had been to Provo and enjoyed visiting the national parks in Utah.

Mining at Red Mountain 2

Mining ruins near Red Mountain #2, near Ouray, Colorado.

I drove out of town south on Highway 550, stopping to take photos of the Red Mountain peaks reflected in a small lake, as well as some mine structures I’d missed on my way in two days ago. Once over the top of the pass, I pressed on through Silverton, talking a gravel road out of town to the northeast toward Engineer Pass and Lake City, then southeast through a narrow river valley (Cunningham Gulch) to the Old Hundred Mine at the base of Galena Mountain. I arrived just at 10:00 in time to take the first tour.

Old Hundred mine location

Location of the Old Hundred Mine on Google Earth.

The Old Hundred Mine

This mine was named after the 100th Psalm, where it says: “Make a joyful noise unto the Lord, all ye lands.” No doubt the prospectors who found this deposit made a very joyful noise! Galena Mountain was laced with veins of rich silver-lead-gold ore, and the Niegold brothers (Reinhard, Gustave, and Otto) staked claims on some of the richer veins in 1872. About 300 feet from the top of the mountain, they located the best vein of all at what came to be called the Number Seven Level. Other veins were located further down. The mountain was so steep that mining the higher levels was very difficult – supplies and equipment had to be lowered from the top of the mountain and ore removed on ropes to the bottom level. A small town grew up at the bottom with a hotel, a saloon, a post office, and cabins for the miners. It was called Niegoldstown. Well-educated and classically trained, the Neigold brothers would entertain the miners during the long winter months with music, operas, and plays.

Change room of Old 100

In the change room of the Old Hundred Mine.

In 1904 additional investment built a trail that winds its way around and up to the Number Seven Level, where a boardinghouse with bunks and a tram station were built perched on the side of the cliff and anchored by cables to the cliff face. A tram station was also built at the bottom of the mountain, and massive foundations poured for a stamp mill to process ore. A long adit was blasted into the mountain just above the mill level with hopes of reaching deeper veins inside the mountain.

Entering the Old Hundred Mine

Entering the Old Hundred Mine on an electric tram.

The boarding house still stands on the side of the mountain. Damaged by deep snows in the winter of 1983-84, the roof has been repaired and the boardinghouse and tram station stabilized by some very brave carpenters and helicopter pilots.

Inside the old hundred mine

Inside the Old Hundred Mine; near Silverton, CO.

The bunkhouse was built to house 40 miners and a cook. Miners would stay there for two weeks at a time, with two shifts rotating through the bunks. When they got their pay after two weeks, they would either take a slow mule down the steep trail (just wide enough for two mules to pass each other and much narrower than that now) or ride the tram buckets down. In Silverton, they would spend their money on gambling, whiskey, and women and head back to the mine after the weekend dead broke. Some miners had better sense, saving up money to send for their families in Cornwall or Ireland or elsewhere.

Charges on the face

Charges set to blast the face at the Old Hundred Mine.

Dynamite in Old Hundred Mine

Dynamite boxes at the Old Hundred Mine

With the improvements made, mining continued in earnest. Over 16,000 ounces of gold was removed from the mountain by 1908, but then the veins dried up. The panic of 1907 also dried up the money for further investment, and the property defaulted back to the Neigold brothers. Eventually the mine was lost to back taxes, and the last of the brothers died in 1927.

Old Hundred mucker

A working mucker inside the Old Hundred Mine.

Other owners worked the mine sporadically until 1967, when the Dixilyn Corporation brought new investment. The Mill Level Tunnel was continued over 5000 feet into the mountain and other levels were also extended and connected. A modern mill was built with better techniques for processing the low-grade ore, but the mine remained unprofitable. By 1973 it was finally realized that the deeper veins just weren’t there. The buildings and mill were torn down and sold for scrap. To find out more about the history of the Old Hundred Mine, go to: http://www.minetour.com/history.php.

For our tour, we donned hard hats and slickers, then boarded an electric tram and travelled deeply into the Mill Level adit. There is something a bit spooky and exciting about zipping along a railroad line underground in an open car. Since this mine only closed in the 1970s, they have kept some equipment inside in working order. Our guide demonstrated a working drill and even a pneumatic mucker, which are not usually available. Lots of old muckers are found with the rust painted over as standing displays outside of the mines (including some at this mine), but this is one of the only times I’ve seen one actually working.

No 7 level painting

Painting of the No. 7 Level at the Old Hundred Mine.

No 7 level

Number 7 Level above the Old Hundred Mine.

The tour was truly enjoyable, and I would recommend it as one of the best in Colorado, along with the Mollie Kathleen Mine tour in Cripple Creek. Our guide was knowledgeable and he gave us a good explanation of the technologies and history of the mine. Running my HD camcorder to record all that the tour guide said meant I couldn’t take many photos during the tour itself and some were taken rather hastily and turned out blurry in the darkness. After the tour I took photos around the mine entrance and of the boardinghouse high above us on the cliff. I also bought a used hard hat in the gift shop to add to my collection.

Hardrock holidays

Poster for the annual Hardrock Holidays celebration in Silverton, CO.

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mucker

Mucker machine that runs on compressed air (Old Hundred Mine).

As my tour through Colorado’s mining towns has progressed, I’ve become much more knowledgeable about hard rock mining techniques. I created a post on basic terms of the parts of a hard rock mine and the phases of its development previously; now, it’s time to learn the terminology of the daily lives of the miners and their 12-hour shifts underground. Since these terms and techniques are common to all hard rock mines, I’ll explain them now before moving on to the second half of my day in Ouray and Telluride. That way, as I describe the specific mine tours, I’ll only have to mention those things that are unusual about each tour.

miners using a jackleg

Miners using a jackleg drill.

Each mine generally had two shifts of 12 hours each. The miner’s shift would begin by reporting to the change room, where they would put on their miner’s helmet (at first a stiffened felt hat, later a helmet with a carbide lamp) and other gear, then they would line up for the hoist to lower them down into the mine shaft in the skip, or man cage. This process would take about an hour. Different miners had different jobs; newly hired men would work the face, more experienced men would run the hoist or set up the dynamite charges and fuses, or work inside the mine as blacksmiths to keep the tools sharp.

Single jacking

Single jacking. The miner would relax his grip at the end of each swing to prevent muscle fatigue, and the jack (chisel) was rotated 1/4 each hit to prevent binding.

Old time miners would single jack the face of the ore body using a chisel and an eight-pound hammer and just one candle. Teams of two men would double jack the face: one man would hold the jack and turn it a quarter turn as the second man would hit the jack with a sledge hammer. In the darkness of just one candle, all the hammer man had to see to aim at was the single slightly reflective spot of the smashed metal at the end of the jack.

jackleg drill

Jackleg Drill (San Juan County Museum).

Eventually pneumatic drills replaced the jacks and hammers, driven by a large air compressor just off the change room at the mine’s entrance. Hoses snaked into the mine to drive the drills. Some mines used tanks of compressed air that were filled up each shift and driven on the tram into the mine. These first drills were called jacklegs because they were set up on a portable leg that could be angled into the face. Instead of a rotary motion, the drills used a hammering motion to pound into the hole. They were also called widowmakers because they put out a lot of dust that got into the miners’ lungs and caused a disease called silicosis, similar to the black lung of coal miners. The silicon dioxide dust would act like glass fragments to cause scarring in the lungs, and after a year or two of mining with a widowmaker, a miner would be “rocked up” and unable to work. They usually died within six months or so.

jackleg instructions

Diagram of how a jackleg drill works (Hard Tack Mine).

Eventually someone thought of putting a hole through the center of the drill iron and pumping water through it to mix with the dust and make a slurry. This created quite a mess to transport out of the mine, but it did control the dust and extend the miners’ lives.

Drill hole pattern

Pattern for drilling holes at the face. The center holes were left open so that the rock would fracture inward. The bottom charges went off last and lifted the rock up and out from the face.

Whether by hand or with a pneumatic drill, the miners would drill a pattern of holes in the face. Each mine used a slightly different pattern, but they all had the same purpose. Once done, dynamite was placed in each of the holes except the center one and fuses with exact lengths were attached so that when the dynamite was exploded, it would start in the first circle out from the center, which would break inward toward the empty center hole. The next ring of holes would explode a millisecond later, then the next, and finally a row of holes on the bottom would explode and lift the fractured rock up and out of the face. These shots were done at the end of a shift, so that the air would be clear when the next shift came in.

mucker instructions

Instructions for running a mucker (Hard Tack Mine).

The new shift would remove the fractured rock, a process called “mucking.” At first it was done by hand with shovels, loading the rocks into ore cars and pushing them to the hoist or out of the adit by hand. Mules were sometimes used, but it was hard hoisting them down into the shaft. They had to be trussed up to get them down, and they would stay in the mines, eventually going blind in the darkness. Electric trams were invented to replace the men and mules. Mucking machines that ran on air were also invented that would be pushed to the face on newly laid tracks, then used to scoop up the rock and lift it into an ore car behind. Another device called a slusher acted as a dragline on cables to pull ore away from the face where it could be more easily loaded. Once the rock was mucked, the miners would eat lunch, then begin drilling the holes for the next shot.

mucker diagram

Mucker operation illustration. The hopper is driven by a chain drive ran off of compressed air.

This was the round of work at the face, which was the active area of a vein going basically horizontally. When they reached the ore bodies, they would follow the ore body up and down from the horizontal levels. This process was called stoping, and it required a different type of drill, called a stoper. It was longer and designed to drill vertically upward. The ore body would be followed in all directions and a chamber would result, with sets of timber emplaced as platforms. The miners would work their way up, building more timber sets and raising the stoper higher and higher. The ore would fall down to the bottom of the stope, usually into a wooden bin with chutes from which the ore could be emptied into an ore car.

stoper diagram

How a stoper works (Hard Tack Mine).

To access the ore body, horizontal levels were blasted at 100-foot intervals down the main shaft, which then proceeded to the veins or stopes. Tunnels heading perpendicularly away from the levels were called drifts. Sometimes to get water or ore out of a mine, a long horizontal tunnel was blasted from the outside to a lower level. This was called an adit. All of these longer reaches were done with a type of drill called a drifter or a Leyner drill. It was sometimes mounted on a vertical column anchored into the rock with a long tray that moved the drill along into the face. Several of these could also be mounted on moveable platforms to lower down a shaft in order to extend the shaft deeper or they would be mounted horizontally to lengthen a level. The holes were often longer (up to 30 feet) so that more rock could be removed at a time from a single blast, and the tunnels were often larger than the drifts that accessed the ore.

leyner drill

A Leyner or drifter drill, for making deeper holes. Several of these could be attached to a platform for drilling a pattern for a drift or a shaft (San Juan County Museum).

So it would progress from shift to shift, 24 hours a day, seven days per week except holidays (Fourth of July and Christmas). Miners in remote camps would work for two week straight and get paid, then go into town for a weekend and blow it all on food, drink, gambling, and other pursuits. They would report back to work broke the next Monday.

Miners came from all over; many were from Cornwall England where they had worked in the tin mines. The Cornish tended to save up their money in order to send for their cousins and other family members to join them. These “Cousin Jacks” were hired on as soon as openings occurred at the mines. Given the prevalence of accidents and silicosis, openings were fairly frequent. The Cornish brought a number of mining terms as well as superstitions with them. The most common was the belief in Tommyknockers, small elf-like creatures that inhabited the mines and communicated with the souls of dead miners. When you heard the Tommyknockers tapping in the mine with their small hammers, it meant someone would soon die and the Cornish would refuse to go anywhere near that part of the mine. Small leftover food morsels or pieces of rich ore were left as gifts to appease the Tommyknockers.

Leyner operation

How a Leyner drill operates (Hard Tack Mine).

Those who managed to survive for several years in the mines as young men would eventually be unsuited for work inside and would have to find work topside or elsewhere (being in your mid-twenties was considered old). The daily wage of three dollars was actually considered pretty good pay back then, but eventually miners unions formed which increased the pay, provided more days off, and reduced the shift times to eight hours.

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mining terms

Mining terminology, at the Creede Underground Mining Museum

As mentioned in my last post, I am embarking on a two-week tour of Colorado mining towns. Before I go, there are some basic mining terms that any greenhorn or tenderfoot like me should know before venturing into a mine. Many of these terms come from the Cornish miners who came to America to work when the tin mines in Cornwall played out in the 1800’s.

First, the basic parts of a mine: you always refer to a mine as if you are facing into it. The part of the mine you are working to drill, load, and blast is called the “face.” The left-side wall is the “left rib” and the right-side wall is the “right rib.” The ceiling is the “back” and the floor is the “foot.” The back is also called the “hanging wall” and the floor the “foot wall” depending on the orientation of the ore vein.

Ore body diagram

Diagram of the original ore body.

A “tunnel” is horizontal and must see daylight at both ends. If it only opens to the outside on one end, it is called an “adit.” If it doesn’t connect to the outside at all, it is a “level.” Levels are like the various floors of a building, only underground in a mine, and they provide access to the ore body. A vertical hole that connects with the surface is a “shaft.” If it is a hole that is dug down from a level or an adit, it is a “winze,” and if it is dug upward it is a “raise.” A hole dug to follow a vein horizontally away from a level or an adit is called a “drift” and to dig out a large ore body going up or down is called a “stope.”

The valuable mineral that you are trying to dig out is the “ore,” along with useless rock called “tailings.” Usually the ore is injected as a hydrothermal body along a fault or other natural zone of weakness in the rock, and the entire mineralized zone is called the “ore body” or “lode.” If it is found as a large vertical mass with branches, it is an “ore chimney” and if it is a thin line following any direction it is a “vein.” Sometimes ore is found as crystals deposited along the walls of a natural chamber. This is called a “vug.” When a vein reaches the surface, it is an “outcrop,” and when parts of the outcrop erode away and are carried down into river valleys by water, avalanches, and gravity it will pile up in still areas of the stream, such as the inner parts of meanders along with gravel. These are called “placer” deposits (pronounced “plah-cer” and not “play-cer”).

exploratory mining

Prospectors mine the placers and conduct exploratory mining

The first miners in a new mining district are prospectors, because they are looking to find, develop, and sell a good “prospect.” Typically the first discoveries are placer deposits, because they are easy to find and work using pans, rockers, and sluices. Once the placers are played out, the prospectors head upslope to find the source outcroppings, or the “Mother Lode.” Once they find evidence of ore (such as associated minerals like iron pyrite or chalcopyrite, quartz, etc.) they will “stake a claim” by pounding stakes in the corners of the land and starting to dig exploratory shafts or adits using hand tools such as picks and shovels. They will use a windlass to haul the “muck” or loose rock out of a developing shaft with a bucket. Claims have to be an allowed size (a long, thin swath of land) and registered in the county mine office to be legal. It’s good to set up with a partner so that when one of you leaves to register a claim, the other can guard it from “claim jumpers.”

Samples of the ore are taken to an “assay” office where they are analyzed chemically to see how much valuable metals are actually in the ore. If the ore is rich, or “high grade” or if the vein widens and appears to continue, the prospector will usually sell out to a mining company with the resources and capital needed to further develop the mine.

Once the mining company buys out the prospectors, it starts to build the infrastructure needed to enlarge the mine. The irregular prospector shafts and adits are enlarged and shored up with timbers. The top of a shaft is boxed in with a “collar” and an adit’s entrance is shored up and extended outward to prevent loose rock from falling into it. This becomes a “portal.” At the top of a shaft, a “headframe” or “gallows frame” is erected out of large timbers or steel with pulleys called “sheave wheels” at the top. A braided rope or cable is brought over the sheave wheel and attached to a metal cage called a “skip” which can carry men or ore buckets in and out of the shaft. The other end of the cable is brought to a “hoist,” which is an electric or diesel winch. As the skip is raised and lowered in the mine, a series of electric bell chimes are used to signal the “hoistman” how far to raise and lower the skip. A mark on the cable tells the hoistman when the skip is “on the level.”

mine expands

After a mining company buys the prospect, it expands the mine and adds infrastructure

As the mine deepens, it will usually encounter underground aquifers or water tables which become a major problem as they start to flood the lower mine shafts. The main shaft must be dug lower than the lowest level and a pump installed to remove the water. This low-lying shaft is called a “sump” and the pumps used ran on steam, diesel, electricity, or compressed air. The biggest of these were the famous Cornish pumps found in some mines.

Eventually the shafts are too deep to economically raise all ore cars, sump water, and men to the top of the shaft. A drainage and ore removal adit is sometimes dug at the bottom of the mine that will drain out the waste water and allow easy passage of ore cars out of the side of the mountain. These adits usually have a slight downward slope to the outside so the loaded ore cars can be more easily moved. Waste rock was simply dumped out of the shaft or portal and created a “tailings pile” downslope from the mine or mill.

integrated mine

Integrated mine and mill. As the mine develops, drainage adits, interior shafts, reduction mills, smelters, and other structures are built.

As the mine gets bigger, with additional levels every 100 feet and a complex set of drifts, adits, winzes, raises, interior shafts, stopes, etc. it becomes advantageous for the owners to build their own mill instead of sending their ore elsewhere for processing. A mill is built on the side of the mountain below the lowest portal. It first sorts, then pulverizes the ore into powder, then concentrates the ore mechanically or chemically. The concentrate is then shipped by rail to a smelter for final processing and purification. Sometimes the concentrated ore is heated in a retort or furnace but not separated into its final constituent metals. This combination of metals is poured into bar-shaped or cone-shaped molds and cooled, creating “dore bars” or “buttons” which contain gold, silver, and other metals.

Once the mine is exhausted of ore, or the shaft extends down below where it can be economically drained of groundwater, or the price of the final metal drops so the mine can no longer turn a profit, it is closed down (sometimes temporarily). Today, mines have to post bonds that force them to reclaim the mine and make it safe once mining has concluded. But in the old west, the mines simply shut down and left everything where it was. Tailings piles are the most obvious evidence of mining, and the rocks are often stained a yellow, orange, or reddish brown color from iron sulfides and sulfates. Rotting timbers poke from the ground, and rusted metal scraps adorn the slopes. Drainage water still seeps from adits, often contaminated with metals or other effluents. And the shafts and portals remain, too often a temptation for the unwise to explore. A few people die each year from cave ins while exploring old mines, or get killed by handling old dynamite left in mines. In some states, such as Utah, a concerted effort is underway to close all of these abandoned mines in the name of public safety but at the expense of history. Other states, such as Colorado, seem to strike a better balance between history and safety.

Mining terms B

More mining vocabulary terms. From the Creede Underground Mining Museum.

Now there are many more terms, such as how a typical miner spends his shift to drill, load, shoot, and muck the face. We’ll talk about these later as they come up on my journey. I’m amazed at how many mining terms have made it into general vocabulary, such as “big shot” [blasting out a large section of the face], “hang-up” [when ore is blasted to fall into a lower chute but gets stuck], “getting the shaft” [to buy a worthless mine], etc. For better or worse, hard-rock mining has had a big impact on our history and our culture.

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Cripple Creek downtown

Downtown Cripple Creek Colorado

This is the second half of my trip to Cripple Creek, Colorado, over the Labor Day weekend. As I described in my last post, we traveled to Cripple Creek on Friday, Sept. 4, 2010 and arrived late at night. The next day, I started out by taking a guided tour of the Mollie Kathleen gold mine, then visited the Cripple Creek Heritage Center right across the road, taking photos of all the displays. They even had a scale model of the Mollie Kathleen.

Anaconda mines

Anaconda mine sites with Cripple Creek and Victor Gold Mine

Now for the rest of our visit: After taking some panoramic video shots of the town from the mine dump behind the heritage center, I drove back down Hwy 67 to the town. I was to meet my wife, ‘Becca, and our two children at 12:30 at the Cripple Creek District Historic Center at the east end of Bennett Ave. (the main street of town). I was a bit early, so I wandered around and took some photos and video of downtown, then ate lunch with my family. I had wanted to visit the Historic Center (a man at the mine told me it was worth visiting both museums) but didn’t want my family having to wait for me, so we decided instead to take the narrow gauge railroad tour. We were almost late for the train, and in the hurry my son William fell down and skinned his knee in the parking lot, so we were trying to get him bandaged up (fortunately we brought a first aid kit in the diaper bag) while the train pulled away. The loud train whistle frightened William some more, and I’m afraid the whole experience wasn’t very great for him or my wife, who had to hold him most of the way. My other son, Jonathan, was having the time of his life, pointing out all the rocks to me (at three he’s already a budding geologist). I tried to videotape the whole thing and take a few photos as well.

Headframes in Victor

Headframes in Victor, Colorado

The train headed south along the mountain grade, over some old tressles and fills, past many old mine workings, to a point about half way to Victor at the abandoned town of Anaconda. It was quite interesting to see the old mine shacks lower on the hillside and the new terraces and trucks working the higher hillsides for the Cripple Creek and Victor gold mine. On the way back we paused on a siding to let the next train pass, and the engineer pointed out the remains of Crazy Bob Womack’s cabin in Poverty Gulch, who was the first to discover gold in the district in 1890. We had a good view of Cripple Creek and Myer Ave., which was the notorious part of town.

WInfield Scott Stratton and I

Winfield Scott Stratton and I

We had to leave for Denver by 3:00, so we had just enough time to drive out to Victor and snap a few photos. There are many headframes on the hillsides around town, including those of Stratton’s Independence Mine and the Portland, which he had a share of. As we left, I had to take one more photo of myself seated on this bench with Stratton himself (well, at least a bronze replica of him).

Winfield Scott Stratton was the first big millionaire of the district, discovering his gold telluride deposit on July 4th, 1891. He had searched unsuccessfully for silver and gold for the previous 17 years, working as a carpenter during the winters to finance his summer prospecting expeditions. He had even built a sign for H. A W. Tabor in Leadville for his opera house while he was prospecting there. He finally decided he needed more education and took courses in mineralogy at the new Colorado School of Mines. In 1891, he scoured much of the Cripple Creek area and found nothing. On the evening of July 3, 1891, he had a dream in which he imagined going back to a granite ledge he had already passed over. The next day, upon revisiting the site, he noticed signs of gold telluride ore, and discovered rich veins in some boulders that had fallen off the main face of the ledge. He staked a claim and named it the Independence, which he eventually sold for $11 million to a group of British businessmen, the highest amount paid to date for any mine, and a large fortune at the time. But Stratton wasn’t one to blow all of his money; he’d learned from the example of Tabor, who was now ruined because of the Silver Panic of 1893. Eventually Tabor came to Stratton looking to sell some mine stock to help pay his debts. Stratton paid him $50,000 for the stock, but never bothered to record the sale at the mine office. Stratton eventually bought a house in Colorado Springs that he himself had built years before and lived there the rest of his life. I had read a biography about him a couple of years ago called Midas of the Rockies by Frank Waters (1937) and now I’ve finally visited the sites he helped to make famous.

Victor Colorado

Downtown Victor Colorado

There is still much I would like to do and see here. I would like to hike some of the paths in Victor, take the tour of the open pit mine, and view the whole valley from the Eagles overlook. But that will have to wait for another trip. At least I have gathered enough footage and photos to make a great video of the Cripple Creek mining district.

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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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Replacing topsoil Eureka Utah

Replacing topsoil in Eureka, Utah

On my visit to the area around Eureka, Utah last Friday, June 4, I not only wanted to visit Mammoth and Silver City, but to also document the efforts by the Environmental Protection Agency to clean up the town. I had traveled through Eureka a few days before on Memorial Day and noticed that the lawn and soil around the LDS chapel in Eureka was being dug up to a depth of about 18 inches. On Friday, crews were in the process of bringing in new soil in dump trucks and spreading it over a layer of black plastic where the lawns used to be. Normally I wouldn’t have noticed it much – just chalked it up to them putting in a new sprinkler system or something similar. But I knew differently. This was the latest site in an ongoing process to replace the topsoil throughout the entire town, which is a huge undertaking. All the old mine sites throughout the district have left a legacy of environmental contamination and pose a danger to careless explorers who try to enter mine shafts or tunnels or ruins.

Ore dump at Dividend

Ore dump at Dividend, Utah

When silver ore was discovered in the East Tintic Mountains by George Rush in 1869, it ignited a stampede of mining claims that spread throughout these mountains. New deposits were soon located and claimed, and the ore was assayed to be rich in silver, gold, lead, zinc, copper, and other minerals, usually in the form of metal sulfides. The most level sites near the mines quickly grew into the towns of Eureka, Mammoth, Silver City, Diamond, Knightsville, Dividend, etc. These towns were usually as close to the mines as possible so the miners didn’t have far to walk, so that miner’s houses and the mine buildings, hoists, smelters, railroad depots, and city businesses all competed for space in the narrow canyons. Tailings dumps of discarded minerals and slag from the smelters covered the hillsides around and above the town. Dust from these piles was blown by the frequent winds (this is western Utah, after all) and blanketed the whole town. Nobody thought much of it at the time. It was all just part of life in a mining town. But the entire topsoil was contaminated with lead and other metals down to about two feet under the surface.

Limestone rip-rap in Eureka

Limestone rip-rap covering a slope in Eureka, Utah

Downtown Eureka with limestone rocks

Clean-up operations near downtown Eureka, Utah

Today, the EPA has identified the area around Eureka as a SuperFund site, spending millions of federal dollars to clean up the contamination.  One by one, the yards of the residents and businesses are being dug up and the soil replaced, brought in from a staging area east of town. To prevent the tailings piles from blowing more toxic dust around the town, broken limestone rocks called rip-rap are being hauled in from a nearby quarry and are carefully placed to cover over the tailings piles to prevent further erosion by wind and water.

Mine dump in Tintic Mts.

Mine dump in East Tintic Mtns.

The work is progressing throughout Eureka, but the entire mining district has the same problem. Recent exploratory work has dug up the tailings piles in Silver City again, leaving the yellowish sulfides once again exposed to erosion. Many of the mine sites in the hills are owned by small-time private owners who keep the mines open on an occasional basis. They don’t have the resources to prevent the erosion of their tailings piles, and much of the East Tintic Mountains is contaminated just as Eureka itself is.

Old mine shaft

Abandoned mine shaft at Dividend, Utah

Another problem in the area is the many abandoned mine tunnels and shafts. Mines today are required to provide reclamation funds before the mine can even open, but it wasn’t an issue in the 1800s and early 1900s when most of these mines were active. The owners took the ore from the hills, then left all the scars, holes, pits, slag, tailings, and buildings behind when the ore ran out and their companies closed. Now these ruins are a hazard to casual explorers; every year or two someone dies falling down an abandoned mine shaft in Utah. The state has begun a program to close off these mines; to place grates or metal doors in the tunnels and shafts or to blast the entrances closed. Over 8000 mine sites have been closed off throughout the state through this program, but many, many more remain to be done.

Knight Smelter at Silver City

Ruins of the Knight Smelter at Silver City, Utah

Smelting or concentrating the ore brought its own environmental problems. Jesse Knight, the silver magnate that started Knightsville just southeast of Eureka, also built a smelter at Silver City in the early 1900s that operated for about eight years. The foundations of this smelter still remain, as do residual chemicals used to concentrate the ore, including mercury. When I visited the site on Friday, I found a man and his two young girls exploring the site. I suggested that he wash off his girls’ hands and shoes carefully once they were done because the whole site is contaminated with mercury (June McNulty, who runs the Tintic Mining Museum in Eureka, told me that he used to play with pools of liquid mercury metal that would seep into pockets around the smelter).

Knight Smelter

Remains of the Knight Smelter at Silver City, Utah

Right to the south of the old smelter lies a large heap of grayish tailings, now slowing growing a crown of weeds and grass. All the tailings left from the Knight mill were scooped up in the 1980s and placed on a pad with drainage pipes running through the pile, then a solution of cyanide was pumped and sprayed over the pile, leaching its way down through the tailings and chelating with the remaining gold and silver. The ore from these mines has been worked and reworked to get every last fraction of value out of it. But now the pile has been left just like all the other piles around, but with the addition of cyanide. I don’t know if steps have been taken to reclaim the pile, but I wouldn’t want to walk around on it.

Leaching pile at Silver City

Cyanide leaching pile at Silver City, Utah

The efforts to clean up these environmental messes is necessary, but it does come at a cost beyond just money. To clean up the town and make it safe to live in, its essential history and character has been changed.  The heavy equipment moving in limestone and soil has shaken apart a number of fragile historical structures, including buildings, homes, and headframes. Where there were colorful tailings piles slowly returning to nature, there are now carefully constructed fresh piles of gray limestone rocks, an ideal hideout and breeding ground for rattlesnakes (no joke here – I ran over one in my minivan as I was driving up the road to Mammoth). Eureka doesn’t look the same as it did ten years ago.

One can argue that Eureka must be dynamic and capable of changing. It’s not a museum but a living town, and change is part of life. But the historian in me hates to see history destroyed in the process. That is one of the main reasons I’ve started the Elements Unearthed Project and have traveled to Eureka several times in the last few years with my cameras and equipment; as the EPA clean up progresses, the town is changing and I want to preserve what can be preserved of the history before it’s gone forever.

Tailings piles at Silver City

Erosion of tailings piles at Silver City, Utah

The beryllium video second half is progressing well. I’ve decided to do the three episodes on the TIntic Mining Districts next instead of blown glass because It’s fresh on my mind and I now have all the footage and photos I’ll need. My goal is to get the beryllium video done and uploaded by the end of this week, then the Tintic videos by mid-July. Then I’ll start hitting the streets looking for financial sponsorship to continue this project.

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