Article by Steve Voynick
Mining – June 1995 – Colorado Central Magazine
Frontier-era miners had a saying that no mine was ever really worked out. They closed or abandoned their mines simply to await “better times.”
Unfortunately, their underground wisdom on mine closures, which reflected only unbridled optimism, was usually dead wrong. Park, Lake, Custer, Saguache, and Chaffee counties have hundreds of abandoned mines that now await not better times, but only the EPA.
Nevertheless, at the Sweet Home, an old silver mine hidden away high in the Mosquito Range west of Alma in Park County, the early miners were right on the money. Three years ago the Sweet Home reopened and produced a fortune, although not in the way the old-timers had envisioned.
The million-dollar fortune wasn’t in silver ore; instead, it came in the form of crystals of red rhodochrosite, currently one of the hottest items on the international mineral collectors’ market. And the tools that really got the job done weren’t drills and dynamite, but geologic inference, ground-penetrating radar, fiber optics, and hydraulic splitters.
The Sweet Home Mine, claimed in 1872 for leadsilver mineralization, holds U.S. Patent No. 106, one of the earliest patents granted under the General Mining Law of 1872. But the mine never became a silver bonanza, for the rich veins of argentiferous galena were too thin, erratic, and elusive.
Those first Sweet Home miners occasionally blasted into pockets of rhodochrosite crystals. Although rhodochrosite, a red manganese carbonate that forms rhombohedral crystals, is not uncommon in Colorado silver mines, large, translucent, well-developed crystals are rare.
The Sweet Home may not have yielded much silver, but did indeed produce some remarkable rhodochrosite crystals. But rhodochrosite wasn’t silver ore and frontier-era miners had little appreciation of mineral æsthetics. The spectacular crystals usually ended up in the mine dumps.
After decades of inactivity, miners reopened the Sweet Home in the 1920s. It produced sporadically in the 1940s and 1950s, but was never more than a break-even operation. By this time, the Sweet Home’s claim to modest fame was not silver ore: It was those eye-catching crystals of red rhodochrosite.
After mineral collecting boomed in the early 1960s, fine rhodochrosite specimens were no longer a pretty curiosity, but an increasingly valuable collectible. In 1966, Sweet Home miners made one final try for silver but soon gave up, investing their remaining capital in a successful search for rhodochrosite. Displaying the best crystal from the trunk of a car in Alma, they sold it to a local collector for $2,500.
The Sweet Home’s day as a silver producer were over and the mine remained inactive for the next twenty-five years. During that time, mineral collectors searched the dumps for small, iron-stained, abraded fragments of the now legendary Sweet Home rhodochrosite. “High-graders,” legally or otherwise, entered the mine to remove crystals on at least two occasions.
By 1990, record collector demand was driving the price of fine rhodochrosite specimens through the roof. The same specimen that bounced around in the trunk of a car and sold for $2,500 in Alma in 1966 was now showcased at the Houston Museum of Science, where experts estimated its value at $250,000.
Several groups of miners and mineral dealers considered leasing and reopening the Sweet Home. Among them were Bryan and Kathryn Lees of Golden, Colorado. Both held engineering degrees from the Colorado School of Mines. As specimen miners and mineral dealers, they had previously mounted two successful Colorado mining ventures for amazonite, a green-blue gemstone variety of feldspars and for crystals of blue barite.
The Lees raised $300,000 in investment capital, leased the Sweet Home property, and hired Bill Kazel as mine manager, along with two local hardrock miners, Rory McDonald and Scott Bets. McDonald’s wife, Carrie, signed on as the surface portal watcher.
The Sweet Home was a portal-accessed, single level mine with narrow, five-foot-wide drifts. The crew completely rebuilt the portal, constructed a drainage system, tore out the mine-gauge haulage rail, installed some ventilation, and slabbed the narrow drift walls to make room for rubber-tired, diesel mining equipment.
“Reactivating an old mine, however small, is an expensive proposition,” Lees points out. “But we had two big advantages. We needed no milling, and we planned to dispose of waste rock as backfill within the existing underground workings. That minimized the environmental considerations and made it easier to meet state and federal permitting requirements.”
Dean Misantoni, former chief geologist at the nearby London Mine, geologically mapped the entire Sweet Home workings in detail at a scale of ten feet to the inch. Lees provided geologic interpretation, correlating such geologic structures as faults and fissures with previously noted rhodochrosite occurrences.
In the Sweet Home, well-formed rhodochrosite crystals occur only within small voids, or pockets, in certain mineralized veins. Searching for the crystalbearing voids is akin to searching for the proverbial needle in a hardrock haystack.
SPECIMEN MINING has few parallels with conventional hardrock mining. The “ore” — fragile and rare crystal specimens within isolated pockets — cannot simply be drilled, blasted, and mucked out. Nor is it economically feasible to “drift” along trends of mineralized veins hoping to encounter random pockets. Even core-drill exploration is useless because of the small size of the pockets and veins.
So how do specimen miners find pockets? Lees starts with geologic inference, mapping known mineralized structures and projecting their trends to predict the existence of pockets with a high degree of probability. Lees uses ground-penetrating radar (GPR), transmitter-receivers of high-frequency electromagnetic energy, to back up his geologic inference. The transmitter emits short bursts of energy into solid rock; the receiver records energy reflections. The biggest reflections come from dielectric discontinuities, such as the interface between a solid rock and a void, thus enabling GPR to “look” into solid rock to reveal the presence of hidden pockets.
IN THE SWEET HOME rock, GPR has detected one-foot pockets at distances of twenty-five feet. Lees combines the GPR data with geologic inference to produce “targets.” Miners then conventionally drill and blast their way toward the targets, usually detecting them physically when a drill steel enters a pocket and “hangs up.”
Lees next determines the pocket’s contents — valuable crystals or nothing at all — with a medical fiberoptic endoscope, the same kind used in arthroscopic surgery. To actually view the interior of a pocket, Lees simply inserts the fiber optic probe through a drill hole. Disappointment is a regular part of the job, for ninety percent of the pockets contain nothing of value.
“But when we do find a rhodochrosite pocket, opening it is an incredible experience,” says Lees. “There’s a great sense of accomplishment and fulfillment, and the mineral beauty of the crystals can be stunning. And there’s also a certain timeless quality. We’re the first to ever lay eyes on crystals that were formed thirty million years ago. It’s an exciting, even an emotional, experience.”
After a rhodochrosite pocket is found, mining methods become critical. Breaking the tough Sweet Home rock takes, as miners say, “a good shot.” Since the necessity of recovering the crystals intact rules out normal blasting, miners make their final approach by drilling short rounds that require only very low-energy detonations to break the rock. Once they expose a small part of the crystal-bearing void, they drill a close pattern of holes only inches apart around it.
At that point Lees takes out his “secret weapon”-a hydraulic splitter. The rod-like splitter core, about the size of a drill steel, consists of two outer shells, called feathers, and a center wedge. After insertion into the drill hole, hydraulic power drives the center wedge forward, forcing the feathers outward. The steady diametric pressure breaks the rock along the line of the drill holes, eventually separating large sections of the pocket walls, called plates, with their crystalline linings intact.
When necessary, Lees also uses a thirty-five pound, diamond-tipped, hydraulic chain saw that actually cuts through sections of hard rock.
By 1992, Lees had opened several small rhodochrosite pockets that yielded enough crystals to “pay the bills.” Then he hit a bonanza — a narrow, six-foot-long pocket filled with an array of remarkable crystals. After opening the pocket, Lees’ crew needed three weeks of precision drilling and slow splitting to remove the plates. Then he needed three more months to clean and restore the specimens. The cost to “mine” that single pocket and to clean the specimens amounted to $50,000.
FROM THAT ONE POCKET Lees extracted, cleaned, and restored a specimen now known as the “Alma King.” It’s a two-foot-high plate of rock covered with thousands of glittering prisms of clear quartz and decorated with crystals of dark sphalerite and blue fluorite. Near the center, as if placed by an artist and contrasting vividly against a white, needle-quartz matrix, is a perfect 4.25-inch “rhombi of translucent, deep red, gem-quality rhodochrosite. Many experts acclaim the Alma King as the finest and most valuable mineral specimen ever mined in North America. Some rank it with the best ever mined in the world.
[InContentAdTwo]
The Adolph Coors Foundation recently acquired the Alma King for the Denver Museum of Natural History. The value of the specimen? Although the price is not publicized, the Coors Foundation is thought to have paid something just short of $1 million dollars.
If you’d like to see the Alma King, it’s now dramatically displayed at the entrance to the Coors Mineral Hall at the Denver Museum of Natural History. Hundreds of other Sweet Home rhodochrosite specimens, including one or two others in the six-figure range, have been displayed at gem and mineral shows and are now in private collections.
Bryan Lees admits that his Sweet Home adventure has a certain undeniable element of romance. “We’re really treasure hunters of sorts,” the professional specimen miner says. “We follow geological, historical, and technological clues to find the treasure, then go about the work of recovering it in good condition. It’s a high-risk business, but it’s paid off at the Sweet Home.”
Bryan and Kathryn Lees and their mine crew will work the Sweet Home again this summer, following another trail of geological and technological leads hoping that it, too, will lead to another rhodochrosite bonanza. After that, they plan to move on to other Colorado specimen mining projects.
“Hardrock specimen mining is an exciting niche in the mining industry. It’s market-driven and has good potential for growth,” Lees says. “But don’t think it’s easy. It takes a lot of determination, and you must be prepared for disappointment. Since there are few precedents to follow, you have to devise and innovate as you go along.” Lees may be right about the growth of specimen mining. With a fifteen-year-long general slump in domestic hardrock metal mining, the supply of good mineral specimens has all but dried up. And you can bet that other specimen miners, in other mines and for other minerals, will try to replicate what Bryan and Kathryn Lees have accomplished at the Sweet Home.
WHEN THOSE FIRST MINERS walked away from the Sweet Home more than a century ago, maybe they did somehow know that they weren’t really abandoning the mine, just letting it wait for “better times.” It took a while, but the “better times” finally came in the 1990s in the form of a timely product, a high-tech approach to getting it out, and a couple of specimen miners who weren’t afraid to take risks.
It makes you wonder just what’s waiting behind the collapsing portals of all those other Colorado mines.
Steve Voynick drilled, timbered, mucked, and blasted in mines throughout the West before taking up a career where he was even less likely to strike it rich — free-lance writing. He lives in Leadville, and his book Climax, the history of the molybdenum mine, will be published later this year by Mountain Press.