A $2.6 billion gold deposit overlooks Wyoming's State Capital

Consulting Geologist Dan Hausel (aka GemHunter)
searching for gold in the Copper King area.

A few decades ago, I came across the Copper King mine in the Silver Crown district west of Cheyenne and 3 miles north of I-80. It seemed like this deposit was just waiting for the right conditions to again be mined.  Although, some claimed this property was mined out, simply because it was not being mined.

"Fleas can be taught nearly anything that a Congressman can." –Mark Twain

A mined-out mine is almost as rare as an honest politician. Properties like the Copper King have considerable potential and await the right group of people, CEO, and favorable economic conditions. It is said, "mines are not found, they are made"! In other words, the stars must align in the right positions to make a mine.

I was lucky enough to examine this mine and nearby properties in the early 1980s for the Wyoming Geological Survey, the University of Wyoming Engineering Department, and the University of Wyoming MMRRI (Mining and Mineral Resource Research Institute). In addition to this property, my field assistant and I mapped all of the accessible mines in this area and searched for other properties with potential. Anyway, we interpreted this as the root zone of a Proterozoic gold-copper porphyry deposit with nearby associated massive sulfide deposits. Years, later, I looked at the property again for a publication for the Wyoming Geological Survey about base metal resources in Wyoming, and then just a couple of years ago, came upon another opportunity to visit the property as a consultant for a group of gold mining companies.

After attracting companies to drill the property over the years when I was at the Geological Survey in Laramie, the Copper King was shown to have a resource equivalent of more than a million ounces of gold! Yes, and this property has just been sitting there, looking at the State Capital, and listening to the I-80 traffic to the south, and the Happy Jack road traffic to the north for all of these decades. Hard to believe, but just 19.5 miles east of the mine, is the State Capitol Building.

Imagine this, sitting next to Cheyenne and stone's throw from the Interstate and from the Happy Jack road, is a rich mineral deposit that has a minimum of $1.54 billion in gold, and $864 million in copper!!! How can that happen? If you know where to go, you can actually drive to this treasure, even in a Honda Fit: $2.4 billion in gold and copper sitting next to the state capital!

Aerial photo showing location of the Copper King mine in relation to the Twin Mountains cryptovolcanic structures.

Recently, US Gold picked up the Copper King mine (Mining Quarterly Spring, 2019). The nifty thing about this property, is that it was originally mined for copper in the 19th and 20th centuries. I even met some of the people who had worked in the mine and mill some decades ago - they were extremely pleasant people and had many stories to tell. The ore was milled across the street from the mine and smelted next to the mill. But the gold resource in those days was not considered important, as it was too low-grade with gold prices at only about $20/ounce. But today's gold price ($1,308/ounce on April 10th, 2019) is 65 times higher than in the past. So, it appears, it may again be economic!

Based on drilling by several companies over the years including the now defunct US Bureau of Mines (the Bureau of Mines was eliminated by the Clinton Administration, even though it was one of the more respected research agencies in the world, simply because it assisted the mining industry), the ore body at Copper King is now known to have measured and indicated drilled resources of 966,000 ounces of gold and 236,000,000 pounds of copper, and an inferred resource of 184,000 ounces of gold and 62,000,000 pounds of copper.

After working on the property a couple of years ago, I was able to show the known ore body was cut off and down-dropped to the east along the Copper King fault. So, part of the ore body remains to be drilled that lies under an unknown thickness of gravel. There is undoubtedly more gold and copper (as well as silver) in this area. There may even be some zinc, as I found sphalerite (a zinc-sulfide) at a nearby property that has similar hydrothermal alteration mineral assemblages as the Copper King. And most porphyry gold-copper deposits include some silver and zinc.

And, it may not end there. The likelihood of gold placers downstream from the property should be considered, but no one has ever bothered looking for gold in gravel. While consulting on this property, I examined core specimens that have visible gold (known as free gold); so it is very likely some gold ended up in the surrounding streams, especially when we have evidence that nearby diamond-bearing kimberlites have had as much as 2,000 to 3,000 feet of erosion since the Early Paleozoic. That could be a lot of gold transported down-stream over a billion+ years from the Copper King that is not all that far from the Early Paleozoic kimberlite pipe in the Colorado-Wyoming State Line district.

Being that the property sits within the Colorado-Wyoming diamond province, near a large group of cryptovolcanic structures (Twin Mountains structurally controlled depressions) I found while consulting for DiamonEx Ltd about 7 miles southwest of the Copper King, some streams in this region likely have placer diamonds. I also found similar cryptovolcanic depressions continuing all the way north to the Iron Mountain kimberlite district in the Laramie Mountains. Some UW students, working on my research grants, also recovered diamond indicator minerals in this part of the Laramie Mountains, as well as many rubies.

Although, practically no one has looked for diamonds in surrounding streams in the Colorado-Wyoming region, there must be millions of diamonds in stream gravels west of Copper King. Not so long ago, some very nice diamonds were recovered from stream gravels in Fish Creek, Rabbit Creek, and others in this region. Two of the placer diamonds weighed in at 5 carats! And as far as gold, I suspect that if anyone did any prospecting in gravels downstream from the property, they would find placer gold in some drainages.

So, get your gold pan and go have a look!

A Gold-Copper Mine for Wyoming?

The Copper King - a gold mine or just another hole in the ground?

Many people and companies looked at the Silver Crown district west of Cheyenne in a quest to find economic amounts of copper particularly at the Wyoming Comstock and Copper King mines. But after decades of searching, no one found enough metal to make a serious venture in the district. The Comstock vein was too narrow and small for economic consideration, and the Copper King porphyry was too deeply eroded and too low-grade in copper to compete with the likes of the giant porphyry copper deposits in Alaska, Arizona, Montana and Utah. Even so, many companies and consultants tried to find the right combination of ore grade, tonnage and metallurgy.

The Copper King is in section 36, which later became State of Wyoming fee land, and was initially developed by the Adams Copper mining and Reduction Company in 1881, and later worked by Hecla Mining Company. Many companies drilled the property including ASARCO (1938 and 1970), the Copper King Mining Company (1952-1954), Henrietta Mines (1972-1974), Caledonia Mines (1987), Compass Minerals (1993-94), Mountain Lake Resources, (1997), Saratoga Resources (2006-2008), and US Gold (2017-18).

Pervasive propylitic alteration of granitic rock collected in the Silver Crown
district by the author, 1982.

Samples collected by Jamison (1912) while at the Wyoming Territorial Geological Survey contained highly anomalous copper, gold and silver values. Later core drilling by the US Bureau of Mines (McGraw, 1954, Soule, 1955) intersected silicified and hydrothermally altered rock at depths to 1,024 feet (Klein 1974). An estimate of in situ ore was made by Nevin (1973) based on the available drilling and the ore zone was described to include 35,000,000 short tons averaging 0.21% Cu and 0.022 opt Au. Not great, particularly at gold price of $106.48 per ounce in 1973 (Hausel, Blog). But gold prices increased over time.

Personally, I've investigated this property a number of times as a researcher and as a consultant. My initial reconnaissance in 1978 led to grants by the University of Wyoming Mining and Minerals Resource Research Institute (MMRRI) to the Minerals Section of the Wyoming Geological Survey to investigate geophysical and geochemical signatures of a group of diamondiferous kimberlites in the Colorado-Wyoming State Line district, search for new kimberlite deposits, and also search for  disseminated metal deposits in Wyoming for the University of Wyoming to conduct heap leaching and in situ metallurgical research. At the time, geologists with the Wyoming Geological Survey investigated several deposits around the state, but the Copper King was the most favorable for this kind of research. Sampling and mapping of the Rambler Mine was conducted on the Bill Ferguson Ranch in the Silver Crown district, and mapping of the Copper King mine on state land (Hausel and Jones, 1982; Hausel 1997). Ferguson (1965) previously sampled the Rambler Mine and provided us with assay reports. Over the years, I also identified visible gold in rock samples on the property - something previously unrecognized.

Potassic alteration at the Copper King mine

Caledonia Resources Inc. of Canada later leased State Section 36 in 1987 for additional drilling. Preliminary results showed a higher grade zone of 4.5 million tons averaging 0.044 opt Au, or about 200,000 contained ounces of gold. Later, Compass Minerals of Reno (1995) did additional drilling finding more mineralization. Additional investigations by the author and several companies including Saratoga Gold identified what appears to be a copper-gold deposit with a potential of 2 million ounce gold-copper equivalent. Now, US Gold's report indicates that the Copper King contains 926,000 Measured and Indicated ounces of gold with 223 mm pounds of copper and an inferred gold resource of 174,000 Inferred ounces of gold with 62.5 mm pounds of copper. In other words, drilling has identified 1.1 million ounces of gold with some copper.

Hydrothermally altered rock at the Rambler prospect

From recent investigations, it is apparent that there is a geophysical anomaly to the west of the known mineralized body as well as a distinct fault break along the eastern part of the ore body which down-dropped the ore to an unknown depth. Will this disseminated gold-copper deposit ever become a mine? This is unknown as it is very low-grade even though drilling shows it has about $2.6 billion in gold and copper metals at present prices (2018). So, now it depends on how much it will cost to recover those metals from the rock, and prices to build gold mines are not cheap.

But a couple of things to think about - one is that this is a deeply eroded gold-copper deposit, and some of that gold eroded in the past 60 million years must be somewhere downstream. In addition, diamondiferous kimberlites in the nearby State Line district as well as scattered throughout the Laramie Range are also deeply eroded and as much as 2,500 feet of diamondiferous kimberlite pipes also eroded and those diamonds must be somewhere downstream in the Poudre River and other drainages.

As far as exploration targets are concerned, companies might search for additional porphyry copper like that at Copper King and the Rambler prospect, search for veins similar to the nearby Comstock mine in the district, search under gravels and soil adjacent to the Copper King fault where the deposit has been down-dropped, search for volcanogenic massive sulfides similar to the Sierra Madre massive sulfides, and finally, I would be tempted to drill at least one or two deep holes to see what exists under the Copper King porphyry.  Not so long ago, a giant copper deposit was discovered under the Resolution porphyry near Superior, Arizona after the property was deemed mined out (Hausel, 2019, 2020).

Looking towards the Rambler prospect, a zone of intense propylitic alteration with 

associated sulfides.

Sulfide-rich shear zone exposed in portal at the Louise mine.

View of the Lousie massive sulfide south of the Copper King. The geology

is that of a Proterozoic island arc very similar to the VMS deposits identified in the 

Encampment district of Wyoming.

Can't argue with visible gold - visible gold adjacent to pyrite seen in core samples of the

Copper King amphibolite.

Gold Deposits Near Cheyenne, Wyoming

Yes, its a silly looking hat. But in Wyoming, even the GemHunter needs to be warm. 

When I began working for the Wyoming Geological Survey, we were a relatively productive government agency in charge of unraveling the geology associated with mineral deposits as well as  in charge of finding new mineral deposits. But, we were one of the smallest agencies in the State: a very sad commentary for a state that makes its living off mining and oil and gas resources. In addition, our salaries were just one step above that of a custodian.

Not only was most of the legislature uninterested in the State's mineral resources, but I found many at the University of Wyoming were also anti-mining. This is a very strange concept particularly since the University of Wyoming and many of the professors owed their jobs and existence to the mining and oil and gas industries. But even educated professors are under the assumption that money grows on trees.

During the first couple of years I worked at the Survey, I was asked to assist in building a Childrens' Museum in downtown Laramie - it was going to have a geology theme. I donated rocks and assisted in building a mine tunnel for the kids to walk through and on the outside of this exhibit, one board member requested we put on a simple pie diagram to show kids and parents how important mining and oil and gas was to the state. It was a pie diagram showing ad valoreum taxes to the state. Whoa - was this a bad idea.

Hydrothermal alteration mineral assemblages found in the Silver Crown district, Wyoming, and on
some nearby properties.

One of the board members, a flaming liberal from the university, demanded that the pie diagram be modified to show mining, oil and gas were not important - she demanded we make up statistics to fit her agenda! "Mining can't be important she exclaimed - it's bad for the environment and attracts dirty people". I mentioned they were dirty because they have to work for a living (unlike her) and mention mining was also referenced in the Holy Bible, and no where did it indicate mining was a bad profession - remember the Golden Fleece? This was a sheep skin used in a sluice to extract gold. As I suspected, she was not into the Bible. Most extreme liberals have never heard of the Bible or any facts.

Visible gold is seen in rock sample adjacent to brassy pyrite in
this sample from the Copper King

That was one of the first times I saw science taking it in the shorts for politics - and this was 30 years ago. I finally quit working at the Children's Museum when the rest of the board sided with the liberal and modified the pie diagram to show mining and oil and gas contributed little to the state. I didn't want to be associated with lies - but over the years, I found this was characteristic of people with political agendas from the state geologist, to the governor, to the president.

When I left the Wyoming Geological Survey, they actually had a Chinese and Russian communist on the staff and a director who thought the US Constitution was made only to control others, and had nothing to do with him. Now why did some of my friends give up their lives in Vietnam?

How did I get onto that subject? Ah, I know, I was thinking about the time I worked on the Copper King property while at the WGS. Over the years, I developed a fascination with different mining districts, and one of my favorites was the Silver Crown district. At one time I had planned to do a detailed study of the hydrothermal alteration patterns at the Copper King mine and acquired drill core from the US Bureau of Mines. I was hoping to find money to pay for thin sections and microprobe analyses, when the director decided the core (several $million worth of core) was collecting dust and without warning, he transported all of the core on a weekend to the city dump.

Stockworks at the Copper King

In spite of this and other set-backs, I was able to spend time on the ground at the Silver Crown district and at the Copper King mine and was able to map the accessible underground mines in the district (Hausel and Jones, 1982) and over the years, I spent time researching the mineralization and alteration at the Copper King mine and nearby properties (Hausel, 1997). It became clear to me that the Copper King was a deeply eroded core of a Proterozoic age gold-copper porphyry system and over the years when I had exploration geologists and company CEOs visiting my office on the UW Campus while they were searching for ideas for gold mines, I told many that this was one of my top picks for a commercial gold deposit. Some of these people listen, and it was picked up time and time again. But like most commercial gold deposits, development awaits the right alignment of the stars.

Most people are under the impression when a commercial gold (or other metal or gemstone) deposit is found, it is "Eureka" and then the mining begins. Unfortunately, that never happens except in the movies. "Mines are made, they are not found" was stated at some talk I attended at the Northwest Mining Convention many years ago. It takes the right circumstances, people, investments, government support, etc, etc, etc. Take a look at the Pebble deposit in Alaska. A prophyry deposit so large that it dwarfs the Bingham Canyon deposit in Utah. Can you imagine finding a $100 billion deposit and no one can figure out how to make a mine out of it?  I can. We found a world-class, $multi-billion gold deposit at Donlin Creek Alaska in 1988, and its taken 34 years so far to put it in production. I found  gold in 1981 at the Rattlesnake Hills, and again, no one yet has made a mine out of it.

Pervasive propylitic altered quartz monzonite

The Copper King mine near Cheyenne, was drilled by the US Bureau of Mines (one of the few productive government agencies that met its demise under Clinton and Gore because it didn't fulfill their political agenda of making things greener - so thousands of government employees were terminated, valuable research ended, all because a few politicians wanted to promote global warming whether fact or fiction) and several different exploration companies. Today, it is reported the property has a gold equivalent resource of 2 million ounces in gold and copper. Hey, now someone should be able to put that kind of property in production especially since it is sitting adjacent to I-80 and just down the road from Cheyenne. Access is good.

And it is apparent that the deposit is bigger - based on exploration and drilling - it is open in every direction (except up, maybe). That's right, drilling has yet to find the limits of the ore deposit. However, the ore appears to end to the east - or does it?  I recently mapped a fault and found that the footwall on the east side had down dropped - how far down is anyone's guess at the moment, but it needs to be drilled to find out if the mineralization continues in that direction. I would be very surprised if it does.

Then there is the problem of having similar anomalies in the area. Terry Klein of the USGS pointed out that there were similar hydrothermal anomalies nearby, and I worked on another I found that appears to be very large, but could not map the anomaly due to private land access problems. 

Remember I mentioned that the deposit doesn't appear to continue up in the sky. When I misled you as considerable erosion has occurred in this area since the Proterozoic. So, large amounts of gold are likely sitting in conglomerates and streams - including some that drain into Cheyenne. Can you imagine that - placer gold in downtown Cheyenne.

References Cited
Hausel, W.D., and Jones, S., 1982, Geological reconnaissance report of metallic deposits for in situ and heap leaching extraction research possibilities: Geological Survey of Wyoming Open File Report 82-4, 51 p.

Hausel, W.D., 1997, The geology of Wyoming's copper, lead, zinc, molybdenum, and associated metal deposits: Geological Survey of Wyoming Bulletin 70, 224 p.

The Copper King Mine, Wyoming - two million ounce deposit

Find out more about the Copper King and other gold 
deposits in Wyoming - its all
in our book on gold deposits.

The Copper King mine (NW section 36, T14N, R70W)  (also known as the Arizona mine) was located in 1881 and developed by the Adams Copper Mining and Reduction Company. The property was later worked by the Hecla Mining Company.

All that remains of the old Hecla mill is a rock foundation on the side of the
hill.

This property has a 2 million ounce gold equivalent of gold-and copper associated with shears, faults, veins, veinlets and stockworks in granodiorite and quartz monzonite that have distinct propylitic and potassic hydrothermal alteration mineral assemblages similar to younger copper-gold porphyry deposits. The geology also suggests that the ore deposit could be expanded. That's right, the eastern flank of the Copper King was down-faulted. So what lies under the Tertiary cover in that area?  Hopefully, drilling and geophysics will resolve that question in 2013 or 2014.

The Copper King is considered one of the five best gold deposits in Wyoming and is likely the root zone of a deeply dissected Proterozoic age porphyry gold-copper deposit.

A shaft was sunk 157 feet with 102 feet of crosscuts on the 80-foot level, and 260-feet of drifts and crosscuts and three large rooms on the 130-foot level. A 100-foot adit was driven near the shaft but stopped short of intersecting the shaft. Some ore was shipped, although the total amount of production is unknown (Ferguson, 1965).

Photo of Hecla smelter located across the road

from the Silver Crown Mill, Ferguson Archives.

The Copper King is a deeply dissected Proterozoic age copper-gold porphyry deposit with disseminated sulfides and stockworks surrounded by propylitic and potassic alteration zones. Fourteen samples collected by Jamison (1912b) varied from 0.22% to 2.43% Cu, 0.06 to 0.42 opt Au, and 0.4 to 0.8 opt Ag. Mineralization at the surface occurs as malachite and chrysocolla: at depth as chalcopyrite, pyrite, minor bornite, pyrrhotite and native copper (McGraw, 1954; Soule, 1955).

Potassic alteration of granodiorite at the Copper King.

Primary hypogene mineralization was intersected during drilling to a depth of 150 to 180 feet by the Bureau of Mines. The primary ore is overlain by an oxidized and leached cap extending from the surface down to depths of 30 to 150 feet (Soule, 1955). Near the Copper King shaft, a zone of intense silicification consists of intersecting quartz veins and veinlets. Extending out from the shaft is a zone of potassium silicate alteration expressed by secondary enrichment of biotite and microcline-quartz intergrowths with some muscovite, sericite, epidote, and sulfides. This potassic altered zone is enclosed by a propylitic altered zone consisting of secondary chlorite and epidote with sulfides (Hausel and Jones, 1982b).

The available drilling data indicate that the maximum metal concentrations were on the order of 1.5% Cu and 0.2 opt Au (Klein, 1974). Drilling by the U.S. Bureau of Mines showed mineralization continued to a depth of at least 1,024 feet. Spectrographic analyses showed traces of lead, zinc, tungsten, and 0.5 to 3.0% TiO2 (Soule, 1955). An estimate of the in situ ore reserves were made by Nevin (1973) based on drilling:

Tons                  Cu                           Au                                  Stripping ratio

(millions)          (%)                         (opt)                                    (waste/ore)

2.8                   0.36                         0.044                                          0.5

6.0                   0.32                         0.038                                          1.2

13.5                 0.26                         0.028                                          1.8

35.0                 0.21                         0.022                                          2.0

In 1987, Caledonia Resources leased the mine to test as a large-tonnage, low-grade, disseminated gold deposit. The company reported preliminary gold estimates on the order of 4.5 million tons of ore averaging 0.044 opt Au (or about 200,000 ounces of contained gold). Sampling suggests the deposit has a minimum strike length of 600 to 700 feet with a 300 foot width that is open at depth (Stockwatch, 1987). More recent data by Compass Minerals expanded the gold-copper resource. The company reported a gold resource of 23 million tons of ore grading at 0.82 grams or essentially 770,000 ounces of contained gold, while Paso Rico Resources indicated the deposit to contain a million ounce equivalent gold-copper resource (Hausel, 2008a). More recent work by Saratoga Gold Mining Company outlined a 2 million ounce equivalent ore deposit containing 1.2 million ounces of gold and considerable copper. And based on mapping by the author, it is likely that this resource will be expanded.

Photo of the interior of the Hecla mill near Cheyenne

Wyoming. JE Stimson Collection, University of Wyoming.

Geochemical and geophysical anomalies suggest the known resource could be increased. For example, a large magnetic anomaly (1,000 ft wide x 2,000 ft long, 450 gamma magnitude), almost identical to that reflected by the Copper King deposit (800 ft wide x 1,500 ft long, 500 ft gamma magnitude) was identified in a gravel covered area 4,500 feet to the southeast. Soil samples over this anomaly returned anomalous values for the pathfinder elements mercury, zinc, and arsenic supporting the presence of hidden mineralization. Geological and geophysical evidence also suggests the presence of sulfides down plunge to the southwest and to the east of the Copper King. An IP (induced polarization) survey identified a moderate to shallow metal factor anomaly trending east-northeast of the principal mineralized area (Klein, 1974).

Mineralized terrains showing location of Silver
Crown district in southeastern Wyoming.



Aerial photo showing location of the Copper King mine

  Will the Copper King ever be mined? If a reasonable mining plan and royalty can be negotiated with the State of Wyoming, the answer is 'yes'. The deposit is mostly on State land which is beneficial. If it were on public lands, the Federal Government would tie this property up in their bureaucratic network until any mining company would give up due to the mountains of paperwork.



Over 30 years, I explored Wyoming and mapped most of the hardrock mining districts and found a few deposits with very favorable geology that needed to be explored further. Besides the Carissa Mine and the Rattlesnake Hills gold deposits, the Copper King was one of the top gold deposits in the state that I felt would be mined with higher gold prices. Today, we have those high gold and copper deposits and with further exploration, I would not be surprised to see this deposit surpass the 2.5 to 3 million ounce equivalent.

What really surprises me is there are other mineral deposits (including gold) sitting at a number of locations in Wyoming - some with surprising size that are being ignored by industry and the State. Some are worth $millions, others $billions and at least one might be worth $hundreds of billions.

Maybe its time to go Gold Prospecting, Diamond Prospecting or Gemstone Prospecting in Wyoming.

 

Geological map of the Silver Crown district

I found it!!!  Yes, the two-million ounce gold deposit at Copper King has even more ore. I
was able to follow and map a fault that offsets the eastern edge of the ore deposit by dropping
it down to the east. This means, there is more ore to be found under a blanket of gravel. How
much more? Need to drill to find out.

Photo of Hecla Mill, JE Stimson Collection