Copper Canyon Skarn Deposits

Site Name

Primary: Copper Canyon Skarn Deposits
Secondary: Fortitude
Secondary: Copper Canyon Mine (underground)
Secondary: West Orebody
Secondary: East Orebody
Secondary: Tomboy-Minnie deposits

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Commodity

Primary: Gold
Primary: Silver
Primary: Copper
Secondary: Lead
Secondary: Zinc
Tertiary: Arsenic
Tertiary: Bismuth
Tertiary: Tellurium

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Location

State: Nevada
County: Lander
District: Battle Mountain District

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Land Status

Land ownership: Private
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: Battle Mountain BLM Administrative District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Newmont Mining Corp.
Info Year: 2004

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Production

Not available

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Deposit

Record Type: District
Operation Category: Past Producer
Deposit Type: skarn, replacement, stratiform, stratabound
Operation Type: Surface-Underground
Year First Production: 1868
Year Last Production: 2006
Discovery Year: 1866
Years of Production:
Organization:
Significant: Y
Deposit Size: M

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Physiography

Not available

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Mineral Deposit Model

Model Name: Porphyry Cu, skarn-related
Model Name: Skarn Au

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Orebody

Form: tabular, stratiform, stratabound

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Structure

Type: R
Description: The Dewitt, Golconda and Antler thrust faults coour at depth. The base of the ore at the West Deposit was defined by the Golconda Thrust fault.

Type: L
Description: The Fortitude upper and lower ore zones formed in place and were separated by the north-striking, west-dipping Virgin Fault and a granite porphyry dike intruded along the fault. The Copper Canyon and Virgin Faults acted as conduits for mineralizing hydrothermal fluids emanating from a granodiorite intrusive body and for later dikes emplaced along the same structures.

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Alterations

Alteration Type: L
Alteration Text: There is a general zonation of calc-silicate minerals around the intrusion that corresponds to the metal zonation in the skarn deposits. In the copper-gold-skarn zone near the contact, the skarn minerals consist of garnet plus chalcopyrite with relatively minor pyroxene, while farther away from the contact, in the gold-silver zone, skarn ore consists of pyroxene plus pyrrhotite with relatively minor garnet. There is strong silicic, potassic, propylitic, phyllic, and pyritic alteration, especially of the granite porphyry.

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Rocks

Name: Granodiorite
Role: Associated
Description: Granodiorite
Age Type: Associated Rock
Age in Years: 38.230000+-0.800000
Dating Method: K-Ar
Material Analyzed: biotite
Age Young: Middle Eocene

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Late Pennsylvanian

Name: Skarn (Tactite)
Role: Host
Description: garnet
Age Type: Host Rock
Age Young: Middle Pennsylvanian

Name: Conglomerate
Role: Host
Age Type: Host Rock
Age Young: Middle Pennsylvanian

Name: Siltstone
Role: Host
Description: calcareous
Age Type: Host Rock
Age Young: Middle Pennsylvanian

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Andradite
Ore: Hessite
Ore: Hedleyite
Ore: Bismuthinite
Ore: Argentite
Ore: Galena
Ore: Sphalerite
Ore: Arsenopyrite
Ore: Marcasite
Ore: Pyrite
Ore: Pyrrhotite
Ore: Chalcopyrite
Ore: Electrum
Gangue: Epidote
Gangue: Calcite
Gangue: Sphene
Gangue: Biotite
Gangue: Chlorite
Gangue: Actinolite
Gangue: Tremolite
Gangue: Diopside
Gangue: Pyroxene
Gangue: Garnet
Gangue: Feldspar

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Comments

Comment (Geology): All dated Tertiary intrusive rocks in the Battle Mountain mining district are late Eocene to early Oligocene in age (41 to 31 Ma) and mostly monzogranitic to granodioritic in composition. Although Tertiary intrusive rocks are scattered throughout the mining district as small stocks and dikes, the main exposed Tertiary intrusive centers are in the Copper Canyon, Copper Basin, Elder Creek and Buffalo Valley gold mine areas. Associated with each of these intrusive centers are porphyry-style (Cu-Au and/or Mo-Cu) alteration assemblages, mineralized zones, and related base and precious metal deposits (Doebrich and Theodore, 1996). The Virgin Vein on west side of the ore zone ranges from 4 to 10 feet wide, up to 40 ft. locally. Oxidized ore persists to greater depths along the Virgin Vein than along the Superior Vein, which is more often characterized by primary base-metal sulfides. Detailed pit mapping of the Fortitude deposit showed that a prograde clinopyroxene-garnet skarn assemblage was overprinted by an actinolite-chlorite-epidote retrograde skarn assemblage accompanied by late-stage calcite.

Comment (Identification): This record encompasses the historic mines involved mainly in the Copper Canyon skarn copper deposits, described in earlier MRDS records #M231290, M234137, M234145 and MRDS # M231290 from which material has been incorporated into this record and additional new material has been added.

Comment (Commodity): Ore Materials: gold, electrum, chalcopyrite, pyrrhotite, pyrite, marcasite, arsenopyrite, sphalerite, galena, argentite, bismuthinite, hedleyite, hessite

Comment (Commodity): Gangue Materials: garnet (andradite), pyroxene (diopside), tremolite, actinolite, chlorite, epidote, calcite, sphene, biotite, potassium feldspar

Comment (Deposit): The East orebody and West orebody were copper-gold skarn deposits located along the north margins of the Copper Canyon granodiorite body, mined in the 1970s. The Fortitude Deposit is a world-class gold-silver skarn deposit that was discovered north of the West orebody in late 1980. The East ore body was within the lower part of the Battle Formation siliceous and calcareous conglomerate, which was altered to quartz, K-feldspar, biotite rock with sulfides distributed throughout. The West ore body was in a garnet skarn surrounded by an envelope of diopside, tremolite-actinolite, and biotite, north of and adjacent to granodiorite contact in Copper Canyon. Total sulfide content (mainly pyrite and pyrrhotite) increased to as much as 75% by volume toward granodiorite contact, with chalcopyrite important closer to the contact. Metal zoning was well developed. The average size of the West ore body was said to be 1,500 m x 600 m x 180 m. The Fortitude Deposit consists of an upper and lower ore zones that formed in place and were separated by the north-striking, west-dipping Virgin Fault and a granite porphyry dike intruded along the fault. The upper ore zone formed in calcareous siltstone and conglomerate of the Battle Formation, and is located east of and in the footwall of the Virgin Fault. The larger, higher grade lower ore zone of the Fortitude deposit formed in limestone of the Antler Peak Formation, located west of and in the hanging wall of the fault. Upper zone ore was discontinuous due to strong structural control and selective sulfide replacement of thin calc-silicate pods or lenses aligned along faults or at fault intersections. The lower zone ore was stratiform and stratabound, elongated NE up to 600 meters long, averaging 150 meters wide and 25-30 meters thick. The lower ore zone ends at a marble front to the north and is cut off to the east by an east-dipping normal fault. To the south, sulfide mineralization continued to the granodiorite contact with diminishing sub-economic grades. In 1992 a low-grade millable orebody of about 500,000 ounces of gold was found between the Fortitude and the West orebodies, called the Fortitude Extension. Although sulfide-bearing rock is continuous from the granodiorite contact on the south to the marble front on the north end of the Fortitude deposit, there is a general zonation of calc-silicate minerals around the intrusion that corresponds to the metal zonation. In the copper-gold-skarn zone near the contact, the skarn minerals consist of garnet plus chalcopyrite with relatively minor pyroxene, while farther away from the contact, in the gold-silver zone, skarn ore consists of pyroxene plus pyrrhotite with relatively minor garnet.

Comment (Development): In 1863, silver was discovered in Galena Canyon and shortly thereafter in 1864, copper and silver were discovered in Copper Canyon with the first development in the district on the Virgin copper vein. The predominantly underground mines produced hand-sorted ore from 1868 through 1875 that was shipped via rail to San Francisco, and thence to smelters in Swansea, Wales. There was a decline in district mining from 1875 to 1900, but in 1909, gold was discovered in Philadelphia Canyon, prompting a rejuvenation of the district. 1916 saw the formation of the Copper Canyon Mining Company, which obtained the main property, discovered new orebodies in the footwall of the Virgin vein and became a major producer of copper from both Copper Canyon and Copper Basin during World War I. In 1936, Copper Canyon Mining Co. discovered a large tonnage of gold-copper orebodies from the surface down to the 300-ft. level. There was intermittent production until World War II when there was another production boom. While the property was under lease to International Smelting and Refining Company in 1941, a 50-ton mill and a 3-compartment vertical shaft were constructed. Copper Canyon Mining Co. later resumed work until a declining copper market forced them to switch to lead-zinc operations in the late 1940s to 1950s. ASARCO did exploration work in the district from 1959 to 1961, when Duval acquired the properties and continued the exploration and development that culminated in the opening of both Copper Canyon and Copper Basin open pit mines in 1967, placing Battle Mountain on the map as one of the largest copper producers in Nevada and the U.S. In 1977, Duval announced plans to phase out copper production in Copper Canyon milling operations because of a severely depressed copper market, while at the same time converting to a gold-producing facility, with the increase in gold prices. Battle Mountain Gold Company took over operations in 1985 and gold took precedence over copper as the primary commodity produced from the district mines through the 1980s and 1990s. The East and West copper-gold skarn orebodies were mined in the 1970s and the world-class Fortitude gold-silver skarn deposit was discovered north of the West orebody in late 1980. After three years of stripping and mining of the lower grade Upper Fortitude ore zone, production from the larger and richer lower Fortitude ore zone began in late 1984, ending in 1993 when reserves were depleted. In 1992, Battle Mountain Gold Company announced that it had outlined a low-grade millable orebody of about 500,000 ounces of gold between the Fortitude and the West orebodies, called the Fortitude Extension. In 2001, Newmont acquired Battle Mountain Gold Company, giving Newmont ownership of the Phoenix property where historic mining has left a halo of lower-grade gold and copper reserves. Gold and copper production is expected to begin at Phoenix in the first half of 2006 The skarn deposits at and near the Fortitude orebody are now part of Newmont?s Phoenix Mine deposit.

Comment (Economic Factors): Between 1871 and 1954, the Copper Canyon Mine produced more than 680,000 short tons of ore yielding more than 9.6 million pounds of copper, 6.3 million pounds of lead, 3.3 million pounds of zinc, 48,000 ounces of gold, and 860,000 ounces of silver. In the 1970s, the West orebody produced about 3.6 million metric tonnes of ore averaging 0.79% copper, 0.86 grams of gold per tonne gold, and 16.1 grams of silver per tonne. Between 1980 and 1993, the Fortitude deposit alone produced 10.86 million metric tonnes of ore averaging 6 grams of gold per ton and 28 grams of silver per ton.

Comment (Location): The Copper Canyon skarn copper deposits are located on Battle Mountain in the vicinity of Copper Canyon and Galena Canyon.

Comment (Workings): All the early mines were developed by underground workings - shafts, drifts - with miles of workings. Later open pit mining largely obliterated the early underground workings. The West Orebody was mined by an open pit now buried beneath dump material from the later larger Fortitude open pit mine. The area is now part of Newmont?s Phoenix Mine development.

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References

Reference (Deposit): Stewart, J.H., McKee, E.H., and Stager, H.K., 1977, Geology and Mineral Deposits of Lander County Nevada: NBMG Bull. 88.

Reference (Deposit): Doebrich, Jeff, 1995, Geology and Mineral Deposits of the Antler Peak 7.5-minute quadrangle, Lander County, Nevada, NBMG Bull 109, 44 p.

Reference (Deposit): Theodore and Blake, 1978, Geology and geochemistry of the West orebody and associated skarns, Copper Canyon porphyry copper deposits, Lander County, Nevada, USGS Prof Paper798-C, 85 p.

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.

Reference (Deposit): Blake, D. W., Kretschmer, E. L., 1980, Gold Deposits at Copper Canyon, Lander Co., Nev., Abstract, Precious Metals Symposium, AIME, Sparks, Nevada.

Reference (Deposit): Sayers, R. W., Tippett, M. C., and Fields, E. D., 1968, The Ore Deposits at Copper Canyon and Copper Basin, Lander County, Nevada: AIME Annual Meeting Paper, N.Y.

Reference (Deposit): Roberts, R.J. and Arnold, D.C., 1965; Ore Deposits of the Antler Peak Quadrangle, Humboldt and Lander Counties, Nevada: U.S.G.S. Prof. Paper 459-B

Reference (Deposit): Hill, J.M., 1915, Some Mining Districts in Northeastern California and Northwestern Nevada: USGS Bull 594

Reference (Deposit): Kotlyar, B.B., and Theodore, T.G., 1998, Multilevel geochemical patterns at the Fortitude gold skarn, Battle Mountain Mining District, Nevada, in Tosdal, R.M., ed., Contributions to the gold metallogeny of northern Nevada: U.S. Geological Survey Open-File Report 98-338, p. 259-263.

Reference (Deposit): Doebrich, J.L., Wotruba, P.R., Theodore, T.G., McGibbon, D.H., and Felder, R.P., 1995, Field guide for geology and ore deposits of the Battle Mountain mining district, Humboldt and Lander counties, Nevada, in Geology and ore deposits of the American Cordillera symposium: Geological Society of Nevada, U.S. Geological Survey and Sociedad Geologica de Chile, p. 327-376.

Reference (Deposit): Doebrich, J.L., and Theodore, T.G., 1996, Geologic history of the Battle Mountain mining district, Nevada, and regional controls on the distribution of mineral systems, in Coyner, A.R and Fahey, P.L., eds., Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Symposium proceedings, Reno-Sparks, April 1995, p. 453-483, CD-ROM.

Reference (Deposit): Blake, D.W., Theodore, T.G., Batchelder, J.N, and Kretschmer, E.L., 1979, Structural relations of igneous rocks and mineralization in the Battle Mountain mining district, Lander County, Nevada, in Ridge, J.D., ed., Papers on mineral deposits of western North America: Nevada Bureau of Mines and Geology Report 33, p. 87-99.

Reference (Deposit): Geological Society of Nevada, 1999, Geology and Gold Mineralization of the Buffalo Valley Area, Northwestern Battle Mountain Trend; GSN Special Publication No. 31, 1999 Fall field trip Guidebook..

Reference (Deposit): Wendt, Clancy, 2004, Technical Report on the ICBM/COPPER BASIN Property, Lander and Humboldt Counties, Nevada, Staccato Gold website: http://www.staccatogold.com/i/pdf/icbm-43-101.pdf
URL: http://www.staccatogold.com/i/pdf/icbm-43-101.pdf

Reference (Deposit): Theodore, T.G., Silberman, M.L., and Blake, D.W., 1973, Geochemistry and potassium-argon ages of plutonic rocks in the Battle Mountain mining district, Lander County, Nevada: U.S. Geological Survey Professional Paper 798-A, 24 .

Reference (Deposit): Theodore, T.G., 1971, Geologic map of the Copper Canyon area, Battle Mountain mining district, Lander County, Nevada: U.S. Geological Survey Open-File Report 71-282, 1:4,800.

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Nevada Gold

Nevada has a total of 368 distinct gold districts. Of the of those, just 36 are major producers with production and/or reserves of over 1,000,000 ounces, 49 have production and/or reserves of over 100,000 ounces, with the rest having less than 100,000 ounces. Read more: Gold Districts of Nevada.