Buckhorn Mine

Site Name

Primary: Buckhorn Mine
Secondary: North Buckhorn pit
Secondary: Junkyard pit
Secondary: South Buckhorn workings
Secondary: Ghost Zone
Secondary: Glory Hole
Secondary: NBMG sample locations 1512-1516, 1551-1554, 1557, 1558

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Commodity

Primary: Gold
Primary: Silver
Secondary: Copper
Secondary: Zinc
Tertiary: Tungsten
Tertiary: Thallium
Tertiary: Antimony
Tertiary: Arsenic
Tertiary: Mercury

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Location

State: Nevada
County: Eureka
District: Buckhorn 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.

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Cominco American, Inc

Owner Name: Equinox Resources Ltd. Joint Venture

Owner Name: Cominco American, Inc.

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: fault breccia; vein
Operation Type: Surface
Year First Production: 1910
Discovery Year: 1908
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

Not available

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Mineral Deposit Model

Model Name: Epithermal vein, Comstock

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Orebody

Form: tabular

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Structure

Type: L
Description: A system of parallel normal faults strikes N10W and controls mineralization. Displacements are less than a few hundred feet.

Type: R
Description: Roberts Mountains Thrust

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Alterations

Alteration Type: L
Alteration Text: Argillization of basaltic andesite host rock is the main alteration. Underlying and overlying sediments are silicified. The upper two-thirds (100 ft.) of the mineralized zone is oxidized, the lower third is pyritic. The oxidation of the upper portion is believed to be hypogene, not supergene. In the oxide zone, white kaolinite-rich rocks are found at the center surrounded by purple montmorillonite-rich rocks in peripheral locations. The change in color typically marks the edge of the possible ore zone. Major elements introduced during alteration include Si, Al, K, and Ti. Major elements depleted in altered rocks are Mg, Ca, Na, Mn.

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Rocks

Name: Rhyolite
Role: Associated
Description: plugs and flows
Age Type: Associated Rock
Age in Years: 15.300000+-0.400000
Age Young: Middle Miocene

Name: Andesite
Role: Host
Description: basaltic flows
Age Type: Host Rock
Age in Years: 16.300000+-0.900000
Age Young: Early Miocene

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Analytical Data

Not available

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Materials

Ore: Pyrite
Ore: Jarosite
Ore: Adularia
Ore: Montmorillonite
Ore: Kaolinite
Ore: Gold
Ore: Marcasite
Ore: Limonite
Ore: Plagioclase
Ore: Gypsum
Ore: Calcite
Ore: Sericite
Ore: Goethite
Gangue: Quartz

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Comments

Comment (Economic Factors): In 1993: geologic reserves were reported to be . 1.1 million tons of ore grading 0.11 opt Au. In 1997, Buckhorn and Buckhorn South (Zeke) geologic reserves were reported to be 24 million tons of ore grading 0.046 opt Au.

Comment (Geology): See Wells and Elliot (1969) USGS open-file report for geochemical and geologic maps of the mine area. Basaltic andesite flows are about 400 ft. thick as determined from resistivity measurements. Beneath the Tertiary rocks are either the cherty Fourmile Canyon Formation, or carbonates of the lower plate assemblage. Extensions of the Jurassic Mill Canyon stock may be present at depth. Rhyolite plugs and flows (15.3, 0.4 ma) exposed four miles southwest of the mine area may be related to hydrothermal system responsible for Au mineralization at Buckhorn.

Comment (Development): The first claims were staked in 1908. In 1910, Buckhorn Mines Co. was organized and a mill was constructed in 1913. This cyanide plant operated 1914-1916, processing oxidized ore mined by glory hole method. Pardners Mines Corp. reopened the mine and operated a flotation mill 1935-1937 to treat sulfide ore. From 1938 to 1978 production was limited to working of the dumps. In 1978, Bar Resources Ltd.aAttempted to process oxide ore from an open pit, but failed due to mining and treatment problems caused by high clay content of the ore. Bethlehem Copper Corp.acquired an interest in the property in 1979. Cominco American's involvement began in 1980 with the purchase of Bethlehem copper. During 1980, Bethlehem blocked out a potentially bulk-mineable orebody in the area of the 1978 Bar Resources pit. A feasibility study was initiated in March 1983. Construction began in September and gold was poured in June 1984. Total capital costs for Cominco American mine development were $12 million. Production costs were $200/oz gold.

Comment (Identification): This record incorporates contains all information in earlier MRDS record W016362 for the historic Buckhorn Mine plus additional updateds material.

Comment (Location): The Buckhorn Mine is located approximately 110 km south of Carlin, 95 km NW of Eureka.

Comment (Workings): Prior to 1985, mine workings consisted of two glory holes and a 1,750 ft. haulage road, along with extensive subsidiary workings. In 1985, ore was being mined by open pit at a rate of 750,000 tons per year with an average stripping ratio of 1.38:1.

Comment (Commodity): Gangue Materials: quartz, kaolinite, montmorillonite, adularia, jarosite, goethite, pyrite, sericite, calcite, gypsum, plagioclase. native gold within skeletal limonite after pyrite and marcasite

Comment (Deposit): Ore occurs as three lenses (North Buckhorn, Junkyard, Glory Hole) along a zone 3000 feet long and 100-1000 feet wide. Barren areas between ore lenses typically contain less than 50 ppb gold.

Comment (Commodity): Commodity Info: AG:AU ratio is 15:1. gold recovery is 67%.

Comment (Commodity): Ore Materials: gold

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References

Reference (Deposit): The Mining Record,v.104, no.41

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): NBMG MI-79; NBMG MI-83 to MI-00; NBMG Map 91 1st, 2nd, 3rd; Amer. Mines (1989), 1989 thru (2000), 1999

Reference (Deposit): Vanderburg, W.O., 1938

Reference (Deposit): Nevada Dept. of Minerals,1994

Reference (Deposit): Monroe, S.C., et al, 1988, Geology and Mineralization at the Buckhorn Mine, Eureka County, Nevada, in Bulk Mineable Precious Metal Deposits of the Western United States, Symposium Proceedings, the Geological Soceity of Nevada, Reno, p. 273-291.

Reference (Deposit): Vanderburg, W.O., 1938, Reconnaissance of Mining Districts in Eureka County, Nevada, USBM Inf. Circ. 7022.

Reference (Deposit): Plahuta, J.T., 1985, Geology of the Buckhorn Mine, Eureka County, Nevada, in Geological Society of Nevada Special Publication #3.

Reference (Deposit): Roberts, R. J., Radtke, A. S., Coats, R. R., 1971, Gold-bearing deposits in north central Nevada and southwestern Idaho, Economic Geology, v. 66, p. 14-33.

Reference (Deposit): Roberts, R. J., Montgomery, K. M., Lehner, R. E., 1967, Geology and mineral resources of Eureka County, Nevada, Nevada Bureau of Mines Bull. 64, p. 68-69.

Reference (Deposit): Wells, J. D., Stosier, L. R., Elliott, J. E., 1969, Geology and Geochemistry of the Cortez Gold Deposit, Nevada, Economic Geology, v. 64, p. 526-537.

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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.