Wednesday, April 14, 2021

Millrock and Volcanogenic Massive Sulfides at the Ferris-Haggarty mine, Sierra Madre, Wyoming

In times past, more than a billion years in the past, the familiar mountainous terrain of the southern Sierra Madre of Wyoming, was actually, nothing more than a flat ocean floor in a vast Proterozoic ocean near a subduction zone, where many submarine hydrothermal vents, along with white and black smokers, erupted hot spring fluids, gases, and base and precious metals. These cooled and crystalized into sulfide minerals filling spaces in fragmented rock. Several such deposits formed in this ancient ocean and are now part of Wyoming and Arizona. For example, the great Ferris-Haggarty mine in Wyoming, produced excellent copper-gold-silver rich 'millrock' (volcanoclastic) such as seen in the adjacent photo of a specimen collected from the mine rib of the Ferris-Haggarty mine. And then, there was the world-class copper-lead-zinc-silver-gold massive sulfide at Jerome: talk about an incredible deposit! 

What is millrock

Prior to 1979, the term 'millrock' was essentially unknown except to a few Canadian geologists. So, when a geologist from Conoco Minerals made a discovery of millrock with distinctive colloform massive sulfides and adjacent volcaniclastic breccias at the Itmay mine in the Huston Park area of the southern Sierra Madre, this was the starting gun for a rush to find minable copper, zinc, lead, gold, and silver. Soon, the Sierra Madre Mountains were filled with geologists searching for evidence of ancient black and white smokers, evidence of eruptive paleo-hot springs, and magnetic anomalies over magnetite-rich massive sulfide deposits. It didn't take long, but soon several volcanogenic massive sulfides were found, but a cat and mouse game was played between prospectors and geologists employing their mining rights on public land, and the card-carrying sierra-club forest service employees who did not like to see mining companies exercise these rights expressed in the 1872 Mining Law. So, every time a new discovery was legally made and claimed, the FS withdrew the area as well as access by using wilderness, roadless, etc. designations. Funny, they were never considered roadless or wilderness prior to the discoveries. Where a major base metal district existed, the FS stopped all, legal, access. So, if any politician tells you we are running out of resources - this is nothing more than an admission of their lack of understanding. There are billions (if not trillions) of tonnes of ore, not only in the Sierra Madre and Absaroka Mountains in Wyoming, but also in nearly every known mining district (past and present) in the world. 

And this was not the first rush to the Sierra Madre. Rich outcrops of gowan containing copper, silver and gold were found in 1897 along what is now known as Haggarty Creek. This led to the discovery of a rich, massive-sulfide deposit dominated by copper, and development one of the greatest mines in the West as described by a geologist with the US Geological Survey. Similar deposits had already been found (1883) in Arizona at the United Verde mine in the Jerome district.

Being a research geologist at the Wyoming Geological Survey on the UW campus, it was imperative I learn all I could about this new discovery because our office was being invaded by Canadian companies who wanted to also search for VMS (volcanogenic massive sulfides), volcaniclastics, and millrock. Well, it turns out that millrock is nothing more than volcanoclastic breccia associated with submarine hydrothermal vents and is associated with volcanogenic massive sulfides (Edwards and Atkinson, 1986). Just think of millrock as fossilized, submarine volcanic (hydrothermal) vents associated with all kinds of massive copper, zinc, lead, silver and even some gold. 

Canadian geologists were well schooled in these types of deposits - they had many up north. This was also true of geologists from Arizona's universities. Such deposits were found on ocean floors where considerable hydrothermal activity occurred. So, massive sulfide metals deposits adjacent to active and prehistoric vents, are referred to as smokers (no, not the cancer-affiliated smokers). And it turns out that the Canadians, who were mining several of these massive sulfides, recognized that the brecciated, volcaniclastic rocks near these smokers and sulfides, were almost always found next to operating mills at operating mines - so, one wise geologist named it 'millrock'
Volcaniclastics at the Itmay mine in the Encampment
district, Wyoming. These types of breccia are found 
adjacent to rich millrock deposits.

Other things of interest around these massive sulfides include colloform textured massive sulfide deposits that likely congealed in oceanic water to produce rounded blebs of sulfide minerals deposited on the sea floor. Other ore occurs in the volcaniclastics (the millrock). The larger the clasts in the millrock, the closer you are likely to be to the original volcanic vent, and potentially, a Mother Lode. 

It turns out that after Conoco Resources found the first volcanogenic massive sulfide deposit at the Itmay mine, other massive sulfides were discovered in the region. So many were found that the Forest Service had to take a deep breath, give up their 8-hour coffee breaks, take some Xanax, and then work an hour or two each week following companies and following geology students who began working on master degrees in the UW geology department under Dr. Robert Houston So, whenever a potentially economic deposit was found, the Forest Service piecemeal withdrew it from mining. And you thought that the US Forest Service was a manager of our public lands. 
Colloform massive sulfide sample from the Itmay mine,

Unfortunately, no one told them. The FS office in Laramie wanted to withdraw the entire Sierra Madre and Snowy Range from miners, even though their directive suggested they should be working for the public, rather than for their own biases. It appears that the Laramie office was filled with card-carrying Sierra Club members who were anti-mining, anti-logging, anti-people, etc, etc.

It turns out that Arizona also had Proterozoic-age island arcs with very favorable volcanogenic massive sulfide (VMS) deposits (Hausel, 2019).  Not only were some enormous VMS and porphyry copper deposits found in the Patagonia Mountains near the old ghost towns of Harshaw and Taylor in southern Arizona (some of which are classified as major to world-class deposits), there are also famous VMS deposits at the old United Verde and United Verde Extension mines at Jerome in central Arizona. Then there are many more, nearby, VMS deposits. 

The United Verde mines were extremely rich massive sulfide deposits - so rich, that mining companies made a fortune mining only the high-grade ore and leaving behind huge tonnages of low-grade ore that likely has considerably more tonnage than the high-grade mined in the past. Some of the high-grade was so enriched in sulfides, that when oxygen reached some of these sulfide ores brought in the mine tunnels, the oxygen began to oxidize ore, giving off so much heat, that some of the rock actually caught fire and burned for years. Just imagine, a rock catching fire in a mine! Within the mine operations, the miners also found excellent black and white, fossilized, smokers that were the source of the ore.  

Rich, copper-zinc-silver-gold gossaniferous highwall exposed at the United Verde mine, 
Jerome, Arizona.

Banded chert was also found in the mines and likely represented siliceous submarine volcanic eruptions that slowly settled by specific gravity in the water, producing color bands based on of slightly differing specific gravity. 

Black smoker on exhibit at a museum
in Jerome
So, similar VMS deposits to Wyomings occur in Arizona.  The VMS deposit at the Ferris-Haggarty mine unfortunately was only partially mined, and no one knows how much ore remains in the ground. Based on the geology of the area, I suggest it could be another Mother Lode. As for the nearby VMS deposits to the Ferris-Haggarty, most were withdrawn from mining as soon as they were discovered, between 1979 and 1984(?). 
Such massive sulfides and associated veins occur at a number of localities in the Sierra Madre, such as at the Broadway deposit, Kurtz-Chatterton, and others. But these do not even get close to the number of VMS deposits recognized in Arizona. 

Steeply dipping, millrock photographed in the Ferris-Haggarty mine by the author.

Massive sulfide from the Kurtz-Chatterton vein
Sierra Madre, Wyoming.

Specularite-Chalcopyrite ore from the nearby Charter Oak mine at Puzzler Hill, Wyoming. This
ore assay anomalous copper, gold and palladium

Massive sphalerite ore (zinc-sulfide) from the Broadway 
prospect, Sierra Madre, Wyoming.

Saturday, August 21, 2010


At the close of the 19th Century, optimism was high that Wyoming would become an important source for copper much like the neighbor states of Colorado, Utah, and Montana. But this dream was short-lived! The dream began with the opening of the great Ferris-Haggarty mine in the Grand Encampment district, and within a short time, it became one of the 30 most important copper mines in the world during the first decade of the 20th Century. But soon, a series of disasters befell on the mining company when the Boston-Wyoming mill and smelter complex at Riverside burned to the ground twice. As a result, the Ferris-Haggarty mine permanently closed in 1908 due to financial problems. Wyoming never again gained stature as an important copper-producing state even though several large copper-silver porphyry deposits similar to those in Montana and Utah, were found at the opposite end of the state immediately east of Yellowstone National Park in the Absaroka Mountains. 
Bald Mountain - the site of a proposed open pit porphyry
copper mine by AMAX in 1980. Note the many drill rig
roads at the top of Bald Mountain.

These properties included Kirwin, Bald Mountain, Stinkingwater, Sunlight and several others and the likelihood of dozens of similar deposits in this region is very favorable. In 1980, AMAX had applied for permits to develop an open pit mine at the Bald Mountain copper-silver porphyry, but the company later dropped their interest in the property. 

The proposed mine site was near Yellowstone. Yellowstone was already withdrawn from mineral expiration activity, and over time, the Absaroka Mountains were piecemeal withdrawn and locked up in wilderness, wilderness studies, primitive areas and other designations. The highly-mineralized and locked up area is now as large as some states, and encloses many gold, silver, copper, zinc, lead deposits in Montana and Wyoming.

A few later times, it looked as if the great Ferris-Haggarty mine might begin a new life in the 20th and 21st centuries: (1st) with exploration by Exxon Minerals, which identified a significant gold anomaly in the mine; (2nd), when the author as a consultant, recommended the property to Black Range Minerals from Australia; and (3rd) when a new company referred to as the Ferris-Haggarty mining company, picked up the property with thoughts of reopening and exploring the old mine. 

The Ferris-Haggarty mine is located within the Grand Encampment district of the Sierra Madre Mountains. The Sierra Madre are a forest covered mountain range that rise from the valley floors of the adjacent Great Divide and Platte River Valley basins to over 10,700 feet at Bridger Peak in the heart of the range. Nearby towns include Encampment, Saratoga, Baggs, Sinclair and Rawlins. The district is known for hundreds of historic mines and prospect pits that were dug to test for copper, nickel, cobalt, platinum, palladium, zinc, lead, tantalum, rare earth metals, garnet and/or gold. The district recently was of interest for platinum-group metals and nickel following discovery of anomalous nickel, palladium, gold, copper, silver and platinum (Hausel, 1995, 1997). and typically attracts hundreds of prospectors and treasure hunters each year to search for gold and diamonds.

Ore specimen from the Ferris-Haggarty ore shoot. One of the great mysteries about the F-H mine was the type of ore 
since the mine had been inaccessible for nearly a hundred years; yet this was one of the greatest copper mines in
the world in the 19th century. Investigations by Exxon Minerals in the 1980s identified a sizable gold anomaly at the mine,
 but the deposit remained basically unexplored along trend and depth (and still does). This specimen suggests considerable
 brecciation of the ore and replacement of the matrix with massive copper. The deposit lies in the middle of Proterozoic
 schists deposited near an island arc possibly 1.6 billion years ago, and is in the middle of a known massive sulfide district 
due to initial research by Conoco Minerals in the late 1970s. Some volcanogenic massive sulfide deposits mined in Canada
 and in Arizona have produced $billions in metals. It is likely that the Ferris-Haggarty still contains sizable ore resources
 and the surrounding region contains several economic massive sulfides - however, during the 1980s, the US Forest
 Service piecemeal withdrew land following every discovery of a massive sulfide deposit in the Sierra Madre Mountains of
 Wyoming essentially nationalizing our natural resources.

For the people who still enjoy working, if the FS would support these kinds of projects instead of withdrawing land, 
Wyomingites and Coloradoites could have hundreds of high-paying mining jobs if any of these massive sulfides were
The first known mining claims in the region were staked in 1868. Six years later, a significant copper discovery was made when copper-stained float was found near the continental divide close to Battle Lake. This discovery led to the development of the Doane-Rambler copper mine in 1881, and the small mining community of Rambler was built adjacent to the mine. Following the discovery, the Sierra Madre Mountains attracted hundreds of prospectors in the search for copper and gold.

Author and geologist -
GemHunter Dan
Evidence of the intense prospecting can still be seen from many prospect pits and abandoned mines scattered all over the mountain range; although, many of these are no longer as visible as they once were due to wasteful expenditures by government-funded AML (abandon mine reclamation) projects, that apparently included new infrastructure at the University of Wyoming, a hospital addition in Wheatland, and reclaiming the same mine sites more than once. At the Ferris-Haggarty mine, more than a $million (pre-biden) was paid for reclamation work that included a modified Walmart kiddy pool used in ion-exchange to extract copper from a minor amount of water leaking from the mine adit. At the New Rambler mine, a company was apparently paid to reclaim its private property which was then sub-divided and sold as cabin sites. 

By 1901, it was estimated that 2,500 prospect holes were dug, several thousand mining claims were staked, and 260 mining companies were operating within the district. Several years following the Doane-Rambler discovery, another significant copper discovery was made in 1897 northwest of the Doane-Rambler mine. Although, the discovery at the Ferris-Haggarty mine was described as hosted by quartzite, recent examinations of the underground workings by the author, suggests the ore is hosted by millrock and the deposit is likely a volcanogenic massive sulfide similar to many other deposits in the district. In the following year, an adit was dug to test this gossan and massive copper was intersected within 39 feet. The ore was incredibly rich, and the first 14-ton shipment averaged 33.18% copper! At this time in history, copper was selling for $0.16 to 0.18/pound and silver was selling for $0.60/ounce. The intersection of incredibly rich ore ultimately led to the development of the greatest copper mine in Wyoming. According to Houston (1992), this was one of the more important copper mines in the West at this time in history, and the mine was ranked as the 27th largest copper producer in the world in the early 1900s (Short, 1958), although the mine would have a relatively short-lived history.

Historical photo of the Ferris Haggarty mine with Tram
Following discovery, the region experienced a mining boom and the town of Encampment along the eastern flank of the Sierra Madre blossomed. Other towns were established including Battle, Copperton, Dillon, Elwood, Rambler, and Riverside. To support the development of the Ferris-Haggarty mine, construction on a 16.25-mile-long tramway began at the mine portal on Haggarty Creek along the western flank of the Sierra Madre range at an elevation of 9,880 feet. From the mine, the tramway ran up the western slope crossing the continental divide at 10,690 feet, and continued down the eastern slope of the range terminating at the Boston-Wyoming mill and smelter at Riverside along the Encampment River at an elevation of 7,200 feet. Both the tramway and smelter were completed in 1902. The tramway was an enormous engineering undertaking and included 304 wooden towers, which supported 985 ore buckets. Each bucket was rated at 700 to 1,000 pounds carrying capacity (Beeler, 1905; Vandenberge, 1906). The structure was the longest aerial tramway in the world at that time (Short, 1958).

The tramway terminal was at the Boston-Wyoming mill and smelter complex that was constructed along the Encampment River at Riverside. This complex had a maximum operating capacity of 500 tons per day (Armstrong, 1970).

The Grand Encampment district was organized in the late 19th century. According to some descriptions, this district originally encompassed much of the Sierra Madre as well as a large part of the adjacent Medicine Bow Mountains to the east. Several smaller districts were included within the parent district such as Battle, Encampment, Purgatory Gulch, Sandstone, New Rambler, Keystone and others.

Historical records from the early 1900s indicate that the Ferris-Haggarty mine was the largest copper producer in the district, followed by the Kurtz-Chatterton, Doane-Rambler, Charter Oak, and at the time, 53 other mines with dozens of other properties in the initial prospect stage (Armstrong, 1970). Many of the deposits yielded rich ore from surface gossans (rusty appearing rock), but only in a few cases did the rich ore continue at depth. Beeler (1905) reported shipping ore from some of the mines often yielded 35% to 49% copper in carload lots. The gold and silver values were uniformly low, although some rich gold samples were found in the oxidized ores at Purgatory Gulch, the Charter Oak mine, and others. During reconnaissance in this region, the author identified several gold deposits of potential interest along with the anomalous mineralization at Puzzler Hill. Anomalous platinum, palladium, and nickel were found on a few properties, and one mine (New Rambler), became one of the only commercial palladium-copper (with associated values in platinum, gold, and silver) mines in North America in the historic past.

Ore from the Ferris-Haggarty mine consisted of mixed chalcocite and bornite, and shipments often yielded more than 35% Cu. By 1900, the Ferris-Haggarty mine was averaging about 550,000 pounds of copper per month (Hausel, 1993).


The Grand Encampment district is divisible into a northern and a southern region based on geology. These two regions are separated by a major east-west-trending structure known as the Mullen Creek-Nash Fork shear zone (Houston, 1993). The shear zone is host to several gold, copper, and some platinum group metal deposits in the Sierra Madre and nearby Medicine Bow Mountains. The shear can be visualized as a zone of intensely deformed rock that is as much as a mile wide in some places, and is thought to represent a fossilized subduction zone, where an oceanic basin to the south was subducted under an ancient continent to the north about 2 billion years ago.

North of the shear, the rocks are primarily 2 to 2.5 billion year old metamorphosed conglomerates, limestones, sandstones, shales, and some volcanics. Such rocks would be expected to occur along the edge of an ancient continent. The principal mineral deposits found in these rocks include uranium- and thorium-bearing conglomerates that locally contain some gold and diamond, gold-bearing quartz veins, copper-bearing quartzite, and modern gold placers. The Ferris-Haggarty mine is located within this terrain.

To the south, rocks are younger and different. These include 1.6 to 1.9 billion year old metamorphosed volcanic rocks (basalts, andesites, rhyolites, tuffs), and volcanic-derived sediments believed to have been deposited in an ancient sea and on volcanic islands. This region also includes some large, circular, layered gabbroic (dark, coarse-grained basaltic rock) complexes that are host to several significant platinum, palladium, chromium, vanadium, and titanium occurrences and anomalies. Other mineral resources include copper- and gold-bearing veins, copper-bearing shear zones, and copper-zinc-bearing massive sulfides and zinc-lead-copper skarns. The northern and southern regions, as well as the shear zone itself, are also considered to have high potential for the discovery of diamond deposits.

FERRIS-HAGGARTY MINE In 1897, a prospector by the name of Ed Haggarty discovered a cupriferous gossan (copper-stained rusty rock) along a drainage that would later bare his name (Haggarty Creek). A shaft (known as the Rudefeha shaft) was sunk in the gossan and intersected massive bornite (copper-iron-sulfide) at 39 feet. Shortly after the massive copper was intersected, the property was sold to the Penn-Wyoming Copper Company and capitalized for $20 million.

Underground at the Ferris-Haggarty mine (copyright photo by W. Dan Hausel)
The ore was described to occur in a fold along a contact between quartzite and schist. The ore zone averaged 20-feet-thick and occurred in brecciated footwall (underlying) quartzite (Spencer, 1904). Locally, the production zone was as much as 65 feet thick, and averaged 6 to 8% copper (many of the larger copper mines today, produce ore that typically averages less than 1% copper). High-grade ore mined from the shoot supplied the Boston-Wyoming smelter at Riverside with 200 to 500 tons of ore per day. Some of the high-grade ore yielded 30 to 40% Cu with some silver and 0.1 to 0.4 opt Au. The ore was mined from a zone that was at least 250 to 300 feet long and was developed to a depth of 300 feet in 1903. The workings may have ultimately extended to a vertical depth of 560 feet prior to termination of the mine operations in 1908.

Ore zone exposed in the workings of the F-H mine - in this
part of the mine 
the ore give the appearance of mill
rock (photo by W. Dan Hausel)
The principal ore minerals were copper sulfides known as chalcocite and chalcopyrite with minor bornite and covellite (Hausel, 2009). Other minerals found on the mine dump include cuprite (copper oxide), pyrite (iron sulfide), malachite (copper carbonate), and chrysocolla (copper silicate). Records indicate that the mine may have produced 21 million pounds of copper with some gold and silver. The amount of ore remaining in the mine is unknown, but could be significant. For example, large unmined blocks and pillars of rock were mapped in the mine during the second world war that contained an average of 5% copper (Ralph Platt, personal communication, 1985). In addition, a sampling program completed in some of the accessible upper workings of the mine by Exxon Minerals in 1988 yielded rock that assayed from 0.1 to 21.3% Cu, 1.1 ppm to 2.34 opt Ag, and 75 ppb to 0.33 opt Au. Resources in this part of the mine were estimated at 928,500 tons of ore averaging 6.5% Cu containing 116,800 ounces of gold. Based on value, the Ferris-Haggarty mine could be considered a gold mine with value-added copper and silver. It should be noted that the rest of the mine remains unexplored in modern times, and the possibility of similar ore deposits in the region is likely!

This sample collected from the ore zone in the Ferris-Haggarty
mine is 
typical of the ore. It is enclosed by selvages of sericitic
 schist (felsic schist) and the copper minerals are all oxidized
include malachite with lesser chalcocite
(photo by W. Dan Hausel
It is interesting that the ore was described to occur as fault breccia in quartzite along a contact with schist (Spencer, 1904). Examination of the ore zone by the author showed that it was indeed brecciated and deformed in a shear zone, but that relatively undeformed samples of the ore showed the ore appears as  mill rock - associated with a massive sulfide deposit. The matrix of this breccia consists of massive copper ore supporting angular lithic fragments. Thus the adjacent sericitic schist may represent   metamorphosed felsic volcanic rock. Until geochemistry and mapping can be completed for the Ferris-Haggarty mine, it may best to refer to the host rock as felsic schist or volcaniclastic. The significance of mill rock is important as similar mill rock has been described elsewhere in the district - such as at the Itmay mine, where mill rock was first described in the district by Conoco Minerals in the early 1980s (Hausel, 1997).
You can find more information about this
copper and gold deposit in our Gold book

Millrock was initially coined by a geologist in Canada when it was recognized many volcaniclastic breccias and their associated ore deposits were found near or adjacent to an operating mill in districts like the Flin Flon massive sulfide district in Canada. The concept was that where you found mill rock with its massive sulfides, you had potentially had a commercial ore deposit. At the time of deposition of the Ferris-Haggarty deposit, about 2 billion years ago, the earth’s atmosphere was starting to accumulate oxygen from stromatolites and their associated reefs. 

Because of the Ferris-Haggarty mine, the economy of the region boomed for nearly a decade, but then problems began in 1906. In 1906, a portion of the mill at Riverside was destroyed by fire. The damaged mill was reconstructed, but in the following year (1907), a large segment of the mill and smelter complex were destroyed by fire.

These disasters were followed by a 35% decline in the price of copper. The price drop, along with the fire damage was more than the Boston-Wyoming Mining Company could handle. The mine permanently closed in 1908 and more than 200 miners were laid off. With the layoff, the towns of Encampment and Riverside became economically depressed and never totally recovered.

Ore zone in the Ferris-Haggarty mine (mill rock) (photo by W. Dan Hausel).
Armstrong, J.R., 1970, Grand Encampment 1898-1912: High Country Treasure: Rawlins Newspaper, Inc., Rawlins, Wyoming, 19 p.
A stretched pebble conglomerate in the region - shows evidence
of an ancient paleoplacer. Some of these paleoplacers in the 
Medicine Bow and Sierra Madre Mountains contain anomalous
uranium and thorium. Anomalous gold was detected in one
drill core and even a diamond was found in another drill core
collected by Superior Minerals in the 1980s.

Beeler, H.C., 1905, Mining in the Grand Encampment copper district, Carbon and Albany counties, Wyoming (2nd edition): Office of the State Geologist, Cheyenne, Wyoming, 31 p.

Hausel, W.D., 1986, Mineral deposits of the Encampment mining district, Sierra Madre, Colorado-Wyoming: Geological Survey of Wyoming Report of Investigations 37, 31 p.

Hausel, W.D., 1993, Mining history and geology of some of Wyoming's metal and gemstone districts and deposits: Wyoming Geological Association Jubilee Field Conference Guidebook, p. 39-63.

Hausel, W.D., 1995, Reconnaissance of the Charter Oak mine and Cu-Ni-Au-Ag-Pt-Pd mineralization associated with the Puzzler Hill layered mafic-ultramafic complex, Encampment district, Sierra Madre, Wyoming: Wyoming State Geological Survey, Mineral Report MR95-2, 11 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.

Ferris-Haggarty ore (copyright by W. Dan Hausel).
Hausel, W.D., 2009, Gems, Minerals and Rocks of Wyoming. A Guide for Rock Hounds, Prospectors & Collectors. Booksurge, 175 p.

Houston, R.S., 1992, Proterozoic mineral deposits near plate margins of the Archean Wyoming Province, USA: Precambrian Research 58 p. 85-97.

Houston, R.S., 1993, Late Archean and Early Proterozoic geology of southeastern Wyoming in Snoke, A.W., Steidtmann, J.R., and Roberts, S.M., eds, Geology of Wyoming: Geological Survey of Wyoming Memoir 5, p. 78-116.

Short, B.L., 1958, A geologic and petrographic study of the Ferris-Haggarty mining area, Carbon County, Wyoming: M.A. thesis, University of Wyoming, Laramie, 100 p.

Spencer, A.C., 1904, Copper deposits of the Encampment district, Wyoming: U.S. Geological Survey Professional Paper 25, 107 p.

Vanderberge, J.H., 1906, An independent engineer's report on the properties of the Penn-Wyoming copper company and the Grand Encampment mining district: Geological Survey of Wyoming Mineral Report MR06-1, 25 p.

Before you go prospecting, arm yourself with geological information.

High-grade copper-gold ore from the Ferris Haggarty ore shoot (copyright photo by W. Dan Hausel).

Classical volcanogenic massive sulfide ore showing colloform texture indicating it was deposited in a marine environment.
Sample collected south of the Ferris-Haggarty mine at the Itmay mine (copyright photo by W. Dan Hausel).

Classical 'Millrock' near the Itmay mine, south of the Ferris-Haggarty. This volcanogenic breccia was deposited by
a submarine hydrothermal vent during the Proterozoic and may be similar in age as the United Verde massive sulfide
in Arizona (Copyright photo by W. Dan Hausel). 
Find more about the Ferris-Haggarty in the 1997 book on metals in Wyoming.

Book published by the author 

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