Chapter 10

Will still has the Narrative

During the first week of March in our Mining Systems class, we were reminded about the field trip scheduled for next week.

“Next week we will be taking a field trip to a mine in the Leadville mining district. The mine is located just south and a bit west of the town of Leadville, Colorado. It is a bit over a hundred miles from here,” our Professor told us.

“The Leadville area and its mines were covered in some of your previous classes, but just as a review, I’ll repeat some of the facts about the town and the area.

“The town of Leadville was founded in 1860 and for a long time it held the distinction of being the city at the highest elevation in the United States. It is situated at 10,152 feet. Two mile high town, as it was called at times. The town has gone through a number of periods of boom and bust during its lifetime, based mainly on the fortunes of the mines and the miners. The current population is only some two thousand people, and this includes a number of hard headed prospectors, who still hope to strike it rich.

Mining in the Leadville district began with the discovery of gold in California Gulch near Leadville in late 1859. By July of 1860, the gold rush was on. These were placer deposits in a number of the streams and water ways in the area, but they were soon depleted. In 1874, miners had an assay done on the heavy black sand that had been clogging their sluice boxes and impeding their recovery of placer gold. It was determined that the sand was the lead mineral cerussite, that carried a high silver content. The Colorado Silver Boom started in 1876, when they had traced the cerussite to its source. Unlike gold, which was in placer deposits, the silver was in veins in the bedrock, and hard rock miners came to Leadville.

“To give you an idea of how valuable these mines were, the cumulative production through 1963 was 240 million troy ounces of silver, 3 million troy ounces of gold, 987 million tons of lead, 712 million tons of zinc, and 48 million tons of copper. If you are familiar with the current price of these metals, you will quickly see just how important this area was.

“All of the original mines were played out by the mid 1960s, and most of the tunnels and shafts have long since been filled in or closed off. The last important mine in the area was the Sherman Mine on Sherman Mountain. It produced some 10 million ounces of silver between 1968 and 1984 in addition to considerable quantities of lead, zinc and gold. It was finally closed in 1994.

“Why have I related all of this, and why are we going there, you may ask? In 3887, the North American Geological Survey conducted the latest in the series of geological surveys of the area going back to 1887. They uses the most modern and advanced equipment and procedures available. The results of the survey weren’t released until late in 3890. They created quite a sensation, as they had found an unexplored lode south of and a bit to the west of the town of Leadville. There was very brisk bidding for the rights to develop the claim, and the winning bidder was ASARCO, American Smelting and Refining Company, who had closed the last productive mine in the area back in 1999.

“They operated the ‘Last Hurrah’ mine and refinery for twenty years. It closed in 3915 after they started mining in 3895. The mine was constructed using the most advanced features and safety requirements. The lowest levels of the mine are presently flooded since they stopped pumping some forty years ago, so we will be touring just the upper levels of the mine. The bus will be leaving from the parking lot in front of this building at 7:00 AM on Monday morning, the 9th of March. You can expect to be back by about 6:00 that evening. Wear warm clothing, as the mine can be very cold. Also wear strong comfortable boots,” the Professor finished. Mare was smiling as we exited the classroom a few minutes later.

Monday morning, the 9th of March, we were up early, and Mare and I had a big breakfast, as the Professor had not mentioned anything about lunch on the trip. We had also purchased some snacks and water to take with us. We and our classmates were out on the parking lot at 7:00 that morning when the bus arrived. There were three of our professors going with us. Two were from our mining classes, but the third one was our old Geology Professor.

Once we were all loaded on the bus, it made good time on Interstate 70 from Golden going west to exit 195, where we turned off onto State Route 91 for the remainder of the trip to Leadville. State route 91 was a two lane road, and we needed to proceed slower than we had on I-70, which is a super highway.

The Leadville of the present was not an impressive town. It was small and the buildings were old. Not ancient or antiques, but certainly more than fifty years old and many were not in the best of condition. We didn’t spend much time there, and had turned onto National Highway 24 which we had hit just outside of the town. Highway 24 went through town and turned right going southwest once it cleared the town. We traveled a few more miles on it before turning off onto a private road that led to the ASARCO refinery and the mine.

A large area around the refinery / smelter and the mine was surrounded by a high fence topped with razor wire. There were cameras covering the fence and lights on poles to illuminate it at night. There were “Keep Out Private Property” signs posted every fifty feet or so on the fence. There was also a large area of tailings visible outside the fenced area. There were guards at the entrance gate to the property who opened it to allow the bus to enter. The bus pulled around in front of the refinery / smelter before we unloaded.

“All of you gather around for a short discussion of the Geology of the area by Professor Barrett,” our Mining System Professor told us in a loud voice, once we had unloaded.

“The Leadville Mining District is located between two mountain ranges, The Mosquito Range to the east and the Sawatch Range to the west. The valley between these two ranges holds Leadville and the head waters of the Arkansas River which flows through the Southern Rocky Mountains and eventually empties into the Mississippi River. A number of Colorado’s fourteen thousand foot mountains are visible from the Leadville area.

“The ores are found in a 2,660-foot-thick section of Paleozoic rocks that overlies the Proterozoic basement and is intruded by Tertiary sills and dikes. Virtually all of the sedimentary rocks host ore. The ores are primarily found as veins in layers of Mississippian Leadville Limestone, which is a Dolomite here, the Devonian Dyer Formations, and the Ordovician Manitou Formations. The Leadvillle Limestone is by far the predominant host for carbonate replacement ore, containing approximately 80 percent of the total.

“The mineralization came primarily from intrusions of Tertiary Period magmas into existing rock formations. All of the mineral ores are generally found as sulfides. Here lead is usually found as galena (PbS), zinc as sphalerite (ZnS), and copper as chalcopyrite (CuFeS2). The major silver ores here are argentite (Ag2S), proustite (Ag3AsS3) and polybasite [(Ag, Cu)16Sb2S11].

“While the District is highly faulted on the east side of the Arkansas River, virtually all of the major faults in the district formed prior to mineralization. There haven’t been any major earthquakes here in recorded history,” Professor Barrett, our former Geology Professor, informed us.

Next there was a briefing by the company agent who went over safety precautions while in the mine before he took us to a small building near the refinery where we were issued coveralls, breathing masks, and hard hats with light units. He also made sure that we all had good boots on.

“These light units are good for up to 12 hours with fully charged batteries. They have been charged over night. Check your unit and make sure that it is fully charged,” he warned us before turning us over to the man who would lead the trip into the mine.

“Hi, I’m Bill, and I’ll be leading you on your tour of the mine. Before we leave, I’ll explain how the mine was setup and some on how it operated,” the fellow told us. He was about 5’-11’’ tall, maybe 200 pounds, with brown hair.

“ASARCO received the license to operate a mine here early in 3891. They had already read the NAGA report on the area before bidding on the license. People were sent out here to check the area and to do a little exploratory drilling before they submitted their bid. In the four years between 3891 and 3895, when mining started, more tests bores were made through out the area to determine exactly where the ‘lode’ was located and where to place all of the necessary facilities to operate the mine.

“Developmental work, including both site work and underground work, began in early 3892. The Decline into the mine was started with a box cut that became a 17 foot high and 18 foot wide tunnel underground. It eventually reached 3.1 miles long to reach the loading area below the crusher level. Before the Decline was started, all of the planning for the locations for the smelter / refinery, the power facilities, the drilling arrangements, the water pumping and crusher locations, the ventilation system, and muck removal had been completed.

“The main shaft was also started that year. It has a concrete lining with a finished interior diameter of 18’-6’’. It reaches from the surface to 1300 feet below ground at the crusher load-out area. The shaft is equipped with a tower-mounted friction winder and two 9 ton skips. The skips hoisted from a loading station on the 1270 foot level and have a hoist speed of 40 feet per second.

“The main shaft is located in a non ore bearing area between the two ore bodies on the site. The main ore body, the southern zone, is the richer of the two and is located at a lower level than the satellite northern zone, which isn’t as rich in minerals.

“Developmental mining is composed of excavation almost entirely in waste rock in order to gain access to the ore bodies. While it includes many things, the more important ones are cutting and drilling the riser lines and levels, plus the ramps to various levels, and the haulage lines. The chambers for the crushing equipment and water pumping equipment are also included. All of this needs to be in place before mining of the ore body can begin.

“While all of this was going on underground, above ground the refinery / smelter was under construction, so it would be ready when the first ore was mined,” he continued.

“Mining started in 3895 in the first stoping blocks that had been prepared. Both open-stope and bench mining methods were used here. The main, thicker hanging-wall ore bodies of deposit were mined by transverse longhole open stoping. Following blasting, the ore was moved to the underground crushers from the open-stope after passing through the grizzly level to the haulage level where it was moved with remote control LHD (loading, haul and dump) machines to the crusher level. From the crushers the ore is moved to the surface by either the 9 ton skip hoist or by 50 ton hauler trucks up the Decline.

“Once a block was mined out, the resulting void was back-filled with a mix of dense tailings and cement powder which was then pumped to the underground site to refill it. This reduced the possibility of cave-ins. We’re ready now to go down into the mine, so you can get a feel for how it actually looked while it was being worked,” Bill finished.

He led us to the Headframe and hoist house following his speech. It was a good half-a-mile walk from the refinery. At the hoist house, he spoke with the operator there before ushering us into the cage for the trip down the shaft into the mine.

“We’ll be going down to the 600-foot level. The levels below that are flooded, as pumping was stopped forty years ago,” he informed us, as the cage started down the shaft. It took us more than a minute to reach the 600-foot level where the cage stopped, and we all exited it. There was an in mine vehicle there. It was a dedicated center-articulated 20-person carrier. It had four wheels with the motor and driver located in the front portion of the unit, and the mining crew rode in the rear portion of the unit. It was a diesel unit and had overhead protection from falling rocks for the passengers and the driver. It was just large enough to carry the 16 students in our class, our three professors, and our guide, who drove the unit.

“We’ll be going to a block that wasn’t mined out because it proved to be very low in the minerals we were mining and not worth the work it would take to mine it. That was the reason that the mine shutdown in the end. The grade of ore fell to so low a level, that it would cost more to mine it than would ever be recovered from selling the minerals. The company tried locating richer veins but was unsuccessful and closed down the mine and the refinery / smelter when the last of the mined ore had been processed,” Bill told us before we boarded the vehicle, and started off toward our destination.

It required more than ten minutes to reach the block that was our destination. The vehicle traveled at about 15 miles an hour. On the way there, we saw areas where what appeared to be chain-link fencing had been used to prevent loose rocks from falling from the walls and ceiling of the tunnel. The material was held to the rock face by long rods that had been cemented into holes drilled into the more stable portions of rock. Bill eventually stopped the vehicle, and we unloaded to move into a tunnel for a good distance.

“Initially, this block appeared no different than any of the other blocks that we mined near it, but on starting work on it, the technical people quickly discovered that it had very low concentrations of minerals worth mining, and it was quickly abandoned with just the few access tunnels that had already been drilled. The blocks around it produced the expected quantity of minerals, but the rock in this block was a harder type and not the same Dolomite as the others,” Bill told us before pausing as we looked at the walls of the tunnel around us.

“Before closing down, the mine produced the following quantities of metals: 1.45 million ounces of gold; 120 million ounces of silver; 500,000 tons of lead; 392,500 tons of zinc, and 27,500 tons of copper during its 20-year life time,” he informed us. He had just finished speaking when Mare’s head snapped around from where she was looking.

“EARTHQUAKE!” she screamed. “Get back to the vehicle,” she added in a loud voice. We were all still looking at her in disbelief when the shaking started, and rocks began to fall around us.

“Get back to the vehicle!” Bill shouted, finally bring us out of our shock, as we all scrambled back toward the vehicle which was parked outside of the block in the access tunnel. We didn’t make it, as rock from the roof collapsed in front of us. This produced a large quantity of dust that made breathing difficult. We definitely needed the masks that we had been issued.

Fortunately, none of us had reached the area where the roof collapsed yet, but it blocked our way, and the internal lights of the mine on this level, at least, had gone out leaving us in the dark.

“Will, you, Professor Barrett, and I will turn our lights on. The rest of you leave yours off for now. There is no way to know how long it will take to dig our way out of here,” Mare told us in a loud voice, taking control of the situation. It was a good thing that someone had taken control of it, for a number of our fellow classmates were in a panic already and were moaning and crying about dying.

“QUIET, all of you,” Mare shouted again. “I need to be able to hear if there is an aftershock coming,” she added.

“You heard the earthquake?” Professor Barrett asked very quietly in a surprised voice.

“Yes, those who engineered us to live on Telchines extended our hearing into the very low frequency range precisely so we would be able to hear the rumble of quakes as they started to give us a little early warning,” Mare told him before starting to give more directions.

“The Professor, Will, and I are going to inspect the blockage. While we are doing that, the rest of you spread out in the tunnel and form a line. We’ll start passing rock from the blockage to you shortly. You will pass them down the line to the other end of the tunnel. I want a couple of you big guys on the end to toss the rocks further down the tunnel, since we have no idea presently how much rock needs to be moved. Nick, you take charge of those tossing the rocks. Every third one of you on the line can turn on your lights so you can see to pass the rocks,” Mare directed.

“You heard her, get lined up,” our Mining Professor directed and was the first one in line near the cave-in.

“Let’s look at this pile of rocks,” Mare told the Professor and me next, and we moved up to the rocks of the cave-in blocking the tunnel.

“We’ll start in the middle of the pile and work our way into it to start. Once we see how it has fallen, we’ll pick a side to work further rather than the entire pile. We just need a passage wide enough to get everyone through. We don’t need to clear the entire blockage,” she told us after we had checked what was in front of us. We quickly started moving rocks. Mare handled the largest ones, moving them to the side away from the line of students passing the other rocks rearward. Bill soon joined us at the head of the line.

“You’ve been in cave-ins before,” he said when we took a short break.

“Yes, they aren’t that unusual on Telchines,” Mare told him.

We had been working for some two hours and had moved a lot of rock before we came to the other side of the blockage. The air was a lot better there.

“The manway rise may be partially blocked,” Bill told us, once we started moving our people past the blockage. “We were still getting some air from it, however,” he finished. The lights were out in the access tunnel also, but our head lamps provided enough light to see where we were going.

As we approached the vehicle, we could see that there were rocks around the vehicle, and the roof of the passenger section was dented, but it looked like it would still run. Our helmet lights also revealed rocks scattered around the tunnel we were in. Bill’s radio came to life shortly after we cleared the blockage.

“Bill, ... Bill can you hear me?” came over it. He quickly pulled it from his belt.

“Harry, we just cleared the blockage at the end of the tunnel we were in. We’re at the vehicle,” Bill told him.

“Bill, is anyone hurt? The shaft is blocked at about the 500-foot level. We’ll need to use the other cage to get you out. Can you move up to the 300-foot level?” came from the radio.

“Harry, it looks like the vehicle is still functional. We can use the access ramp to get up to the 300-foot level, if it isn’t blocked. We’ll have to see. No one was injured in the quake, but some of the students have sore hands and shoulders from moving the debris from the cave-in at this level,” Bill told the man up top.

“Let’s get loaded and get out of here in case there are any more aftershocks,” Bill told us, replacing his radio. The Professors quickly ushered the students onto the vehicle.

“Marianne, I would like you to ride up front with me in case we run into any problems,” Bill told her.

“Okay,” Mare agreed, and I joined the rest of the students in the back of the vehicle. The Professors were the last ones on after they had accounted for everyone.

The trip up the circular ramp went rather slowly, as we weren’t sure if it was blocked anywhere. We did encounter some debris fallen from the sides and top of the ramp tunnel, but Mare was able to clear all of it by herself. None of it was major and there were no blockages. We eventually arrived at the 300-foot level and made our way to the shaft.

There were some minor obstructions on this level also, but Mare and Nick cleared all of them easily. When we arrived at the main shaft, a cage was sitting there waiting for us. Bill had been in touch with those above most of the way up here.

Once we were all loaded on the cage, Bill informed those in the hoist house, and the cage started up, but at a slower speed than they had used when we came down. We had all unloaded and moved away from the Headframe, when the ground started shaking again, and a huge geyser of air and dust came up the shaft and into the open Headframe.

“Aftershock?” Professor Barrett asked when things had stopped shaking.

“Possible,” Mare answered. “I couldn’t hear it up here, but there could have also been a major collapse in the mine.”

“There hasn’t been a major earthquake on Pendery Fault in this area since the Paleozoic Period, some 39 million years ago, and we had to be here today when there was one,” Professor Barrett said in an exasperated voice, before turning back to Mare.

“Marianne, I’m not going anywhere with you again. You live too exciting a life for someone my age,” he told her. Mare just smiled.

In the meantime, Bill and the others working here had been staring at the cloud that had come up the shaft.

“I don’t believe there will be any more trips into the mine. Not for a long time, it’s probably too dangerous now. The company may close it down totally now,” he said in a very quiet voice.

Following that, we walked back to the area where the bus that brought us here was parked. There were medical personnel there to assist those with scrapes, bruises, and abrasions to their hands and other areas. I noticed that there were no abrasions or scrapes on Mare’s hands, even though she had handled much more rock and moved heavier pieces than the other students or I had. There was also food and water for us. It was now early evening, and we were all hungry from the work we had done clearing the cave-in. We had all also been wound tighter than an alarm clock since the earthquake. There was no time or desire to go over how the ore was processed here, not with this class, not today or maybe ever. We all had to sign a release from the legal eagles of the company before we could board the bus.