GOLD RUSH WYOMING!

It's hard to believe that it has been more than three decades since I discovered gold in the Rattlesnake Hills in central Wyoming and classified the new gold district as an Archean (>2.5 billion years old) greenstone belt. Gold in the Rattlesnakes is similar to rich deposits mined at Cripple Creek, Colorado.

One of the first gold discoveries in the Rattlesnake Hills - a deposit named "Lost Muffler" after the
author donated a muffler from a 1975 Bronco to an outcrop along UT Creek in the Rattlesnakes.
Sample of pyritized, auriferous exhalite from the greenstone belt.

Some questions that need to be asked: (1) Where did the time go? (2) How come such attractive gold deposits comparable Cripple Creek have not been made into a mine? (3) Why doesn't the State of Wyoming get off its duff and make this a show piece and financially attractive gold play to attract gold miners to Wyoming? (4) Gold was found in exhalites, veins, stockworks and breccias and also predicted to occur in contact metasomatic deposits related to the intruding Tertiary alkalic volcanics into the greenstone belt rocks and adjacent limy rocks in the sediments - so can we anticipate more drilling? 

Goat Mountain Tertiary instrusive into the greenstone belt rocks.
In foreground is one of several gold-veins.

The first four questions pertain to gold in the Rattlesnake Hills. After I found gold in this district and started a gold rush in 1982, I thought this area would one day have a gold mine. But I also thought the mine would have been developed by 1985 or 1986.

Prior to this discovery, I started a gold rush in 1981 in the Seminoe Mountains. But that area has never really been explored and was tied up for years by a promoter who was interested in making too much money for the property. I also started a mini gold rushes to Purgatory Gulch in the Sierra Madre in 1988, Garrett along the western flank of the Laramie Range in 1989, Mineral Hill in the Black Hills in 1990, Puzzler Hill in the Sierra Madre in 1995 and several rushes to South Pass in the 1980s and 1990s.

My map board sitting on one of the gold-bearing stockworks I found in the district.

 

gold-bearing breccia with my map board

Government doesn't work! And when it does, it's usually out on a coffee break! When was the last time you found a government employee willing to help you (and give you correct information)? When was the last time you saw a government employee actually working? All government agencies (especially Congress) should be placed under a Sunset law and every 2 years they should be able to prove they provided some benefit the public and cut costs. If not -  hit the delete button and delete the trash! It this were to happen, it wouldn't take long and the list of government agencies would quickly diminish, we would have a balanced budget, and a few remaining agencies would learn how to work for the people who pay their salaries.

Gold-silver-copper vein from Pickwick prospect,
Absaroka Mountains.

Sorry, got off on a tangent. Its easy to do when government is filled with corrupt politicians and swamp people - take Biden for instance - PLEASE! Back to geology. 

Wyoming is an extreme anomaly. The state produced considerably less gold than the states surrounding it, yet it sits in the middle of craton with some greenstone belt synforms. Cratons usually have considerable gold (as well as diamonds, nickel, platinum group metals, etc). So where is all of that gold hiding? Unfortunately, a good part of it was taken from the public by the Federal government!. Yep, those extraordinary gold-silver-copper deposits in the Absaroka mountains and Yellowstone those incredible copper-zinc-gold-silver volcanogenic massive sulfide deposits in the Sierra Madre Mountains, those platinum-group metals in the Medicine Bow Mountains, were all withdrawn from exploration and claim staking - shouldn't that be decided by the public who owns the land, rather than a bunch of card-carrying sierra club members driving around in government vehicles. It doesn't stop there. The great Carissa gold mine at South Pass was taken from the public by the State of Wyoming as has been much of the South Pass greenstone belt.  There there are strategic metals at the Lake Owen layered complex and the Mullen Creek layered complex also removed from exploration. SO, whatever happened to the 1872 mining law? And for that matter, whatever happened to the US Constitution, and where did the backbones go for the Supreme Court?



Colloform volcanogenic massive sulfide with pyrite
mantled by chalcopyrite in magnetite matrix discovered by
Conoco Minerals in 1979 and quickly and quietly withdrawn 
from public land by the US Forest Service. A deposit 
similar to the United Verde massive sulfide deposit.

But there are still some good gold deposits that need to be investigated further (until the goverment takes these also). Take for instance the Oregon Buttes- Dickie Springs 28.5 million ounce Tertiary paleoplacer at the base of the South Pass greenstone belt. Where did all of that gold come from? Well, Hecla showed anomalies right under the northern edge paleoplacer that were likely the source of the gold - why isn't anyone looking for this?  Then there is the question of the Seminoe Mountains-Miracle Mile gold-diamond paleoplacer along the northern edge of the Seminoe Mountains. What is there? Where did all of the gold and diamond stability minerals come from?

Stockworks in Copper King granodiorite

How about the Copper King gold deposit near Cheyenne? I like this one and have for many years and its the reason why I spent time looking at the hydrothermal alteration characteristics. Over the years, I was able to get companies to look at the property - it is a deeply eroded root zone of a porphyry gold-copper deposit that now has about 2 million gold-equivalent ounces. This property has possibilities all around it. I found evidence of hydrothermal alteration all around this deposit and mapped a fault zone along the eastern edge that offset the ore deposit, with a block down dropped on the east flank - so there is likely more gold in that block. And what is at depth? Some of the porphyry deposits in Arizona have very high grade deposits hidden at depth. Then there are similar anomalies identified by

Klein (1974) and myself.

Looking for gold - the author in 2012 searching for the mother lode

Then how about the Kurtz-Chatterton gold-copper-silver deposit and the Ferris Haggerty copper-gold-silver deposit? And the list goes on.

Gold Discovered in the Rattlesnake Hills, Central Wyoming

In 1981, an application was made to the University of Wyoming MMRRI research center for grant funds at their request. UW Engineering was looking to build a new institute to conduct research on in situ and/or bulk minable mineral deposits. Thus at their request, a grant proposal was made to investigate the Rattlesnake Hills (RSH) in central Wyoming for bulk-minable gold deposits (Hausel and Jones, 1982 a,b). The geology of the RSH appeared to be very favorable for bulk-minable gold mineralization due the the presence of a large, Archean greenstone belt intruded by more than 42 alkalic plugs. The area had been investigated for the petrology of the alkalic plug by Pekarek (1977) without any regard to potential mineralization. The belt had an excellent source bed for gold (greenstone belt rocks) and several heat engines necessary to mobilize gold from the greenstone belt (alkalic intrusives) and the Tertiary intrusives potentially provided brecciation and permeability of the intruded rocks.

Thus, in 1982, the initial discovery of several significant gold anomalies were made in the RSH of central Wyoming during the initial search for disseminated gold mineralization by W Dan Hausel, economic geologist of the Wyoming Geological Survey. The access route from the north was so difficult, that the muffler for the State field vehicle was ripped off of the vehicle. In honor of the muffler, the first gold discovery in this complex was named 'Lost Muffler' by Hausel. A grant was provided by the University of Wyoming Mining and Mineral Resource & Research Institute. Based on what was known of the geology at that time, it was predicted that the RSH had high potential for discovery of disseminated gold mineralization & by Hausel and Jones (1982a). In addition to disseminated gold, high-grade gold mineralization was detected in veins and exhalites (Hausel and Jones, 1982b) and gold was also detected in banded iron formation and in a large stockworks in gneiss. The RSH was interpreted as a fragment of a greenstone belt (Hausel, 1996).

Gold Discoveries

This was one of the great discoveries in North America. Gold was predicted in this belt in 1981 and verified in 1982 by Hausel. This was followed by several research studies - all that led to additional gold discoveries by Hausel at the Wyoming Geological Survey. A short time after the discovery, John Ray, exploration manager for ACNC, stopped into the Wyoming Geological Survey at the University of Wyoming asking for information on various mineral properties. ACNC, like most mining companies, sought information about geology and mineral resources in Wyoming from the Wyoming Geological Survey. Other companies visited the Wyoming Geological Survey and were provided the same information. A short time later, several gold anomalies were discovered by American Copper and Nickel Company.

It was a completely new discovery.  It is very unfortunate that others who entered the district more than 20+ years after the initial discoveries attempt to take credit and credit others for the discovery - some who were likely not even geologists, let alone born at the time of the discovery. A discovery that is well-documented in more than a dozen publications and in press releases. Maybe a sign of the times - for example, the initial discovery of the Donlin Creek gold deposit in Alaska was made by seven geologists - including three from Wyoming. Yet, years after the discovery, others attempt to take credit for this discovery also. Only due to the efforts of one of the 7 geologists - Richard Garnett, was the Donlin Creek discovery certified by the PDAC of Canada.

In 1977, Hausel was employed by the Geological Survey of Wyoming (as it was known at that time) to investigate mineral deposits in Wyoming. His first project was to investigate the Colorado-Wyoming State Line district for diamondiferous kimberlite. A group of kimberlites had been found by Eggler (1968) and McCallum and Mabarak (1975). Hausel's assignment was to produce a geological map to promote Wyoming’s resources by attracting a diamond company to test for commercial mineralization and he was hired by Daniel N. Miller Jr, director of the WGS.

During mapping, a group of 9 kimberlites were discovered that had been missed by previous investigations (Hausel and others 1979, 1981). Over the years, more than 600 cryptovolcanic structures with kimberlitic affinities, diamond indicator mineral anomalies, and some kimberlites were made, but nearly all remain untested.

After the first couple of years of focusing on diamonds, Hausel began to look for other mineral deposits and made several hundred gold, silver, platinum-group, base metal and gemstone discoveries. News of these discoveries were published in local newspapers, on the Internet, in books, Wyoming Geological Association newsletters and Guidebooks and in annual reports of the State Geologist and US Bureau of Mines.

Discovery of a New Gold Region in Wyoming

In 1981, a search for gold the RSH west of Casper began. Based on what was known of the geology, this area had great potential for discovery of low-grade disseminated gold & high-grade gold. Initial research was funded by a grant from the University of Wyoming MMRRI (now defunct) to search for bulk minable gold so that the university could search for a large grant to develop metallurgical recovery systems (Hausel and Jones, 1982a).

In 1977, there was no pragmatic interest in the RSH and only limited academic interest. Pekerek (1977) successfully defended a dissertation on the igneous petrology of Tertiary alkalic rocks; this followed an earlier study by Carey (1954, 1959). Both focused on the genesis of the igneous rocks, but the older Precambrian rocks remained unmapped and unexplored.

Auriferous vein in front of Goat Mountain.

Why should this region contain gold? The basement complex (Precambrian) was similar to South Pass & had been disrupted by several volcanic eruptions. Such Precambrian complexes often have rocks with above normal gold content. They are referred to as greenstone belts and in many places in the world, the terms ‘greenstone belt’ and ‘gold belt’ are essentially synonymous.

So here was an excellent source bed for gold that was intruded by high-temperature heat engines (Tertiary alkalic igneous rocks) that provided heat & fluids to leach gold from Precambrian rocks and focus the precious metals in fractures and replace select minerals in the host rocks.

Thus, armed with these concepts in 1982, field research began. However, the State of Wyoming assay budget was only about $100, thus sampling was selective. Even so, a whole new gold district was identified during this and subsequent investigations - something that rarely happens. The samples assayed yielded as much as 0.25 opt gold and the Lost Muffler vein as exposed on the surface was traced over a strike length of 2.5 miles. In addition to the samples collected in the RSH, a few samples were assayed from the Seminoe Mountains (one assayed 2.87 opt Au) greenstone belt. Both discoveries resulted in gold rushes with dozens of companies, consultants and prospectors running to the hills.

The RSH had excellent potential for significant gold. Over several years, the greenstone belt was sampled & mapped. While mapping, gold was detected in old Archean (~3 billion years old) veins, fractures, exhalites (a vein like deposit), stockworks & in much younger Tertiary (~42 million years old) breccias & igneous rocks. American Copper & Nickel entered the district & made additional discoveries in exhalites (veins). This was followed by Canyon Resources & Newmont Gold. These companies explored breccias & made a million ounce gold discovery (Hausel, 1996; Hausel and others, 2000). As predicted, the RSH had high potential for discovery of a large tonnage disseminated gold deposit associated with Tertiary volcanics (Hausel and Jones, 1982a). More recently, Evolving Gold initiated exploration in 21st century at what was initially named Sandy Mountain (their North Stock) (Hausel, 1996) & intersected major auriferous zones at depth between Sandy Mountain and Oshihan Hill where a large brittle breccia had been mapped by Hausel (1996).

It became apparent that the basement rocks in the RSH represented a fragment of an Archean greenstone belt similar to South Pass and to other rich gold districts in Australia, Africa and Canada (Hausel, 1994, 1995, 1996). The RSH belt continues under Tertiary sediments to the south, east & west. And a large part of the belt is missing. Based on geology, this fragment sits under Tertiary & Paleozoic cover to the north. How much of the belt remains hidden is unknown, but the geology indicates what is hidden is larger than that exposed – so yes, there are likely undiscovered hidden gold deposits in the RSH!

During mapping and sampling of the RSH, gold anomalies were found at several locations (Hausel, 1982, 1989, 1994, 1995, 1996, 1997; Hausel and Jones, 1982a, b). In addition to the Lost Muffler vein, another 4500-foot zone jasperized breccia vein was mapped that was weakly anomalous in gold with sporadic enriched zones. Nearby, iron formation also contained anomalous gold.

A stockwork along the southwestern margin of the RSH was anomalous. This, the breccias and Tertiary plugs at Sandy Mountain & Oshihan Hill were considered significant (Hausel, 1995, 1996; Hausel, personal field notes 1981-1995). Several grab & composite chip samples of brecciated metamorphic rock in the Antelope basin, at Sandy Mountain and at Oshihan Hill contained gold. These were collected over a surface area of one-square-mile suggesting a sizable, disseminated gold deposit!

In the vicinity of 3 Tertiary alkalic plugs (see map below) - Goat Mountain, Sandy Mountain, and Oshihan Hill, the country rock is brecciated & locally gossaniferous supporting the presence of disseminated and replacement gold – which was the original intent of the University of Wyoming grant.

During past drilling in this area by Canyon Resources and Newmont in the 1990s, a large disseminated gold deposit averaging 0.042 opt Au was identified. It is possible that Newmont identified a gold resource of >1 million ounces (Hausel and others, 2000).

But what is exciting is that Evolving Gold intersected a rich gold anomaly at depth. This area mapped by Hausel (1994, 1995, 1996) occurs along the flanks of Sandy Mountain & Oshihan Hill in a low lying area that was recently named Antelope basin. According to Evolving Gold, a high-grade 215-ft thick zone was intersected in a drill hole along the south flank of Sandy Mountain.

Drilling

Recent drilling by Evolving Gold intersected a large auriferous ore body in sections 24 and 25, T 32N, R88W. This area, mapped by Hausel (1994, 1995, 1996) along the flanks of Sandy Mountain (north stock) & Oshinan Hill (south stock) is significant.Geology. According to Evolving Gold, their targets in this area include the following: (1) Alkalic gold system with potential for a multi-million ounce gold deposit, (2) Multiple porphyry targets, including southeast porphyry zone, (3) Mineralized porphyry dikes – 30.5m at 1.89 gpt Au, including 15.2m at 3.11 gpt Au, (4) Deep stockwork mineralization with grades to 8.2 gpt Au.

The following drill results are reported by Evolving Gold:

North Stock Zone (Sandy Mountain)

RSC-003 146.3 meters @ 2.92 gpt Au

RSC-020 67.1 meters @ 10.80 gpt Au

RSC-089 158.5 meters @ 2.64 gpt A

Geological map of the Rattlesnake Hills gold district (by Hausel, 1996).

Antelope Basin (Breccia between Sandy Mountain and Oshihan Hill):

RSC-019 163.1 meters @ 1.25 gpt Au

RSC-042 76.2 meters @ 1.70 gpt Au

RSC-078 76.2 meters @ 1.77 gpt Au

Gold Porphyry Target

RSC-006 14.3 meters @ 2.21 gpt Au

RSC-027 35.1 meters @ 1.74 gpt Au

RSC-027 30.5 meters @ 1.89 gpt Au

RSC-020 lies 464 ft southwest of drill hole RSC-007. RSC-007 was drilled along the eastern flank of Sandy Mountain. RSC-020 intersected a mineralized zone that was 120-ft thick.

At RSC-007, 464 ft to the northeast, 430 ft of mineralized rock was intersected. At RSC-003 located 670 ft north of RSC-007, 480 ft of mineralization was intersected.

Breccia found at Sandy Mountain during mapping project by Hausel.

Drilling to date has identified a mineralized body that has a 1440 ft strike length that is 640 ft wide and 1760 ft deep. The average grade of mineralized zones are 0.03 opt Au. The data supports a central high grade mineralized zone surrounded by a low grade gold halo producing a large tonnage gold deposit that will likely be minable by open pit and underground mining.

So will there be a gold mine in the RSH? In 1981 & 1982, this greenstone belt was considered to have high potential for commercial gold deposits. RSH also has the added attraction of disrupted zones associated with Tertiary intrusives. The area is located in the middle of nowhere with no active streams & no population to speak of.

However, there is an old saying in the mining industry - "mines are not found, they are made". Whether Evolving Gold can make a mine out if this property remains to be seen. There are many factors involved in any company and its investors and the involvement of government interference and environmental groups who look to stop all human progress. EV has a good property that was considered highly prospective 25 years ago. If they can make a mine out of this property, it will result in other gold mines in Wyoming. Problems seen by the industry with Wyoming has been its reputation for gothic politics that is only comparable to Louisiana and an incorrect perception that the state is poorly mineralized. Even so, the latter has been proven wrong (Hausel, 1989, 1997, 1998, 2000, 2009; Hausel and Sutherland, 2000).

Drill data by EV supports a central high grade mineralized zone surrounded by a low grade gold halo in a large tonnage gold deposit. This is a significant deposit that was initially mapped by Hausel as a large breccia zone nearly a mile long! This discovery will result in increased activity in Wyoming and notable increases in Mineral Hill, Black Butte, Bear Lodge Mountains, South Pass, Seminoe Mountains, Granite Mountains & Sierra Madre in Wyoming as well as in the Tobacco Root and other supracrustal terrains in Montana.

Granite Mountains

The RSH are part of the Granite Mountains. The Granite Mountains are actually hills and probably should be called the Granite Hills. These hills form a belt of Archean rocks immersed in a sea of Cenozoic sediments. The Precambrian terrain is divided into two general units: (1) a complex belt of amphibolite-grade metamorphic rocks exposed along the northwestern and northern margins of the Granite Mountains at Tin Cup and the Rattlesnake Hills-Barlow Gap areas, & (2) 2.6 Ga (billion year old) granites in the center of the uplift. These are intruded by later tholeiitic dikes that cut the granite & metamorphic rocks (Stuckless and Peterman, 1977). Along the northern edge of the hills, Tertiary (40 to 44 Ma – million year old) alkalic phonolites & latites cut the Precambrian rocks (Pekerek, 1977).

The schists in the hills are metavolcanic schists and gneisses that were metamorphosed to amphibolite grade at 2.9 Ga. However, Sr87/Sr86 ratios are unusually high for rocks of this age. To explain such high ratios, these rocks likely formed as much as 3.2 to 3.3 Ga ago (Peterman and Hildreth, 1978).

The metamorphics have steep, southerly dipping, northeasterly to easterly foliation trends (Hausel, 1995, 1996). These include quartzofeldspathic gneiss, augen gneiss, epidote gneiss, biotite gneiss, metagreywacke, amphibolite, metabasalt, minor serpentinite & banded iron formation (Peterman and Hildreth, 1978; Hausel, 1996). At Barlow Gap, both oxide- and silicate-facies BIF are reported (Bickford, 1977). In the Tin Cup belt, massive sulfides are found in hematitic iron formation along with scattered copper, gold & iron anomalies & exotic ornamental stones & gemstones including agates, jade, sapphires & rubies (Love, 1970; Hausel and Sutherland, 2000; Hausel, 2009). Diamonds were also reportedly found in this area by a prospector from Laramie - Eugene Clark.

Summary

The RSH is a newly discovered gold district that remained overlooked until several gold discoveries were made in 1982. This was followed by additional discoveries from 1982 to 1995 (Hausel, 1996) along with discoveries made by John Ray of ACNC. In the 21st century, Evolving Gold and others entered the district and interested gold anomalies by drilling, more than 20 years after initial gold discoveries made by Hausel and Ray in the 1980s. With an assay budget of $100/year, the Wyoming Geological Survey was unable to drill, but predicted where gold would be found and verified the presence of anomalous gold with a very minimal assay budget. It is very exciting to see the extraordinary gold intercepts from recent drilling in the area proposed by Hausel as a bulk minable target in 1982. The exploration and work that has been conducted by Evolving Gold in recent years is extraordinary and we are all hoping to see Wyoming's first gold mine in nearly a century.

How to Prospect for Gold