Buffalo Valley Gold Mine

Site Name

Primary: Buffalo Valley Gold Mine
Secondary: Buffalo Valley Mine
Secondary: A/B/O Complex
Secondary: Dore Hills
Secondary: North Margin Zone

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Commodity

Primary: Gold
Primary: Silver
Secondary: Copper
Tertiary: Arsenic
Tertiary: Nickel

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Location

State: Nevada
County: Lander
District: Mill Canyon District

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Land Status

Land ownership: BLM Administrative Area
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 District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Fairmile Goldtech, Inc.
Info Year: 2004

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: contact -metamorphic, -metasomatic, hydrothermal stockwork/stringers
Operation Type: Surface-Underground
Year First Production: 1924
Year Last Production: 1990
Discovery Year: 1916
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: Skarn Au

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Orebody

Form: tabular

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Structure

Type: L
Description: The Havallah Sequence of the Buffalo Valley Mine has a homoclinal appearance. With certain exceptions, beds strike NW to slightly east of north and generally dip 45-65 SW or West. Buffalo Valley Mine is situated in a fault block that is bounded on the east by the western range-bounding fault of Battle Mountain and on the west by another west-dipping normal fault, which is known locally as the Front Fault.

Type: R
Description: Golconda Thrust

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Alterations

Alteration Type: L
Alteration Text: Contact metamorphic effects in the upper structural unit of the Havallah Sequence: non-calcareous silty lithologies are converted to biotite hornfels; slightly calcareous, siliceous and argillaceous siltstones are metamorphosed to calc-silicate hornfelses (diopside + quartz plagioclase, clinozoisite, epidote). Sulfides are restricted to later fractures. Endoskarn: sulfide-poor calc-silicate mineral assemblages which occur as alteration products of porphyry dikes are common west and southwest of the open pit, rare in the open pit, and absent east and north of the pit. In some hand specimens, endoskarn alteration can be observed as envelopes about individual quartz veins, e.g. plagioclase-quartz-pyroxene-bearing inner envelopes (hornblende destroyed) and relict hornblende-stable outer envelopes. Potassic alteration: shreddy hydothermal biotite is abundant in dikes in the open pit and the degree of biotization is independent of proximity to quartz veins. Prograde skarn: a few unequivocal but rare examples of coarse grained garnet-pyroxene skarn have been exposed in the center of the open pit, interbedded with calc-silicate hornfels. These skarns contain pyrite, although it is unclear whether it was deposited synchronous with skarn silicates. Retrograde skarn: pyroxene hornfels and less commonly basalt and biotite hornfels locally are intensely altered to dark green chlorite, pyrite, and nontronite(?). This assemblage has been reported to carry free gold.

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Rocks

Name: Alluvium
Role: Associated
Age Type: Associated Rock
Age Young: Tertiary

Name: Ash-Flow Tuff
Role: Associated
Age Type: Associated Rock
Age Young: Eocene

Name: Granodiorite
Role: Associated
Age Type: Associated Rock
Age Young: Eocene

Name: Shale
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

Name: Quartzite
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

Name: Siltstone
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

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

Name: Argillite
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

Name: Chert
Role: Host
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

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Analytical Data

Not available

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Materials

Ore: Pyrite
Ore: Gold
Ore: Chalcopyrite
Ore: Malachite
Ore: Chrysocolla
Gangue: Clinozoisite
Gangue: Diopside
Gangue: Biotite
Gangue: Quartz
Gangue: Hematite
Gangue: Limonite
Gangue: Epidote

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Comments

Comment (Commodity): Ore Materials: auriferous pyrite, native gold, chalcopyrite, malachite, chrysocolla

Comment (Commodity): Gangue Materials: limonite, hematite, quartz, biotite, diopside, clinozoisite, epidote

Comment (Deposit): The early orebodies that were mined underground were associated with the frontal fault striking N18E and dipping 40-55W. The more recently mined deposit developed by open pits strikes N30W and truncates against the frontal fault.

Comment (Geology): Rocks of the Havallah Sequence in the Buffalo Valley Mine area can be grouped into 3 local units (and their metamorphic and metasomatic equivalents): 1) a lower structural unit consisting of chert, lesser shale and siltstone, minor pebbly sandstone rich in black chert clasts, and minor limestone; 2) a sill or lava flow of fine grained basalt; and 3) an upper structural unit consisting of non-calcareous to weakly calcareous siltstone, quartzite, and shale. The basalt and upper structural unit are exposed in the pit. Variably altered granodioritic porphyry dikes intrude the Havallah Sequence rocks throughout the mine area and are interpreted to be part of a late Eocene(?) porphyry system, inferred to be related to a larger subjacent pluton. Some dikes carry anomalous gold values, indicating that gold deposition post-dates intrusion of the dikes. Unaltered, unmineralized intercalated ash flow tuffs and alluvium overlie the Havallah Sequence rocks and dikes. Based on the spatial correspondence of au-bearing pyritic veins with the swarm of dikes in the pit and the presence of minor au occurrences associated with outlying porphyry dikes, Seedorff (1991) suggests that gold deposition is related to the Copper Canyon porphyry system. Roberts and Arnold (1965) report the presence of a vein containing pyrite and chalcopyrite 800 feet SE of the historic workings which assays up to 2.0 oz/ton gold. This is likely in the area which has been developed as an open pit. According to shipment records from 1924-1951, the gold and silver content of the ore increases with an increase in copper.

Comment (Identification): This is a new record incorporating all material from earlier record # M231308 as well as additional information. Do not confuse this deposit with the Buffalo Valley molybdenum prospect that lies 7 km to the south at the SW tip of Battle Mountain in secs. 21 and 28, T31N, R42E (no MRDS record). This record has been merged with data from record #m233793, which has been deleted.

Comment (Location): The Buffalo Valley Mine is located between Timber and Mill Canyons. UTM is to shafts of historic underground workings at the north end of the current open pit.

Comment (Workings): Historic underground workings aggregate 3000 feet and include 5 adits, one of which is 600 feet long and another 400 feet long. In addition, 40 shallow pits and trenches have been dug on the surface. Three levels, connected by stopes and raises, and an inclined shaft which extends 220 feet below the surface constitute the main underground workings. After 1988, development was by open pit methods. The buffalo valley mine and surrounding acreage totals over 18,000 acres.

Comment (Development): Prospecting in the area of the Buffalo Valley Mine began in the 1860s with the discovery of gold placers. In 1916, Buffalo Valley Mines Co. purchased 28 unpatented claims from C. Ganser and others, which were then developed as the underground mine. Production was almost continuous from 1924 to 1941, and also in 1951. A 10-ton cyanidization plant was built in 1925 and 1196 tons of ore were treated by 1933. Total reported production through 1951 was approximately 3000 tons. Numerous independent exploration companies explored the Buffalo Valley Mine from the mid-1960s to 1985. In 1985, Horizon Gold Shares Inc. acquired a 99 year mining lease on 158 unpatented mining claims at the Buffalo Valley Mine. Horizon then expanded their land position by locating an additional 679 unpatented claims. At the time of Horizon's acquisition of the property, there existed a database collected from previous exploration efforts that consisted of over 200 short percussion drill holes, 7 diamond drill holes, 214 rotary drill holes, over 3000 gold assays collected from surface, underground, and drill hole samples, surface and underground geologic mapping, and metallurgical and feasibility studies. Horizon mined the Horizon as an open pit-heap leach operation from 1986 to 1990. In December, 1988, Horizon formed a joint venture with Chevron Resources Company to explore the Buffalo Valley property. In 1989, the Horizon/Chevron venture had discovered additional near surface gold occurrences in oxidized veins to the north, southwest, and east of the open pit and had identified an underground resource in gold-bearing oxidized veins beneath the existing pit. Fairmile Goldtech acquired the Buffalo Valley property in the early 1990s. Drilling on the property by Fairmile in 1994 established significant gold mineralization along the Front fault, a north-south striking, 40-50? west-dipping structure that has been traced for over 2,000 feet south of its intersection with the main Buffalo Valley structure. A geological resource within the Front fault zone of more than 350,000 ounces of gold was recognized. This is in addition to an underground geological resource in excess of 250,000 ounces of gold at the historic Buffalo Valley mine. At the Dore Hills prospect, about 3,000 feet north of the old Buffalo Valley pit, drilling confirmed the presence of similar mineralization with short intercepts in the 0.1 to 0.2 ounce per ton range.

Comment (Economic Factors): Production was almost continuous from 1924 to 1941, and also in 1951. A 10-ton cyanidization plant was built in 1925 and 1196 tons of ore were treated by 1933. Total reported production through 1951 was approximately 3000 tons. More than 40,000 ounces of gold were produced from 1989 to 1991. In 1994, Fairmile GoldTech reported resources of about 700,000 ounces of gold in both underground and open pittable material.

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References

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.Johnston, Ivan, and others, 1999, Geology and gold mineralization of the Buffalo Valley area, northwestern Battle Mountain Trend; Trenton Canyon Mine; North Peak Mine; Buffalo Valley Mine; Redline gold skarn deposit; Copper Canyon gold skarn, a review; Marigold Mine; Geological Society of Nevada, Special Publication, vol.31, 261 pp., 1999.

Reference (Deposit): Denver Mining Record, 9/14/94 and 11/30/94.

Reference (Deposit): Doebrich, Jeff, 1995, Geology and Mineral Deposits of the Antler Peak n7.5-minute quadrangle, Lander County, Nevada, NBMG Bull 109, 44 p.

Reference (Deposit): Horizon Gold Shares Inc., Form 10-K for 1991.

Reference (Deposit): NBMG, 1994, MI-1993

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): Horizon Gold Shares Inc., Annual Report for 1987.

Reference (Deposit): Horizon Gold Shares Inc., Annual Report for 1988.

Reference (Deposit): Horizon Gold Shares Inc., Annual Report For 1989.

Reference (Deposit): Horizon Gold Shares Inc., Form 10-K for 1990.

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

Reference (Deposit): Quade, J. and Bentz, J.; Field Exam May 11, 1982

Reference (Deposit): Seedorff, E., Bailey, C. R. G., Kelley, D., and Parks, W., 1991, Buffalo Valley Mine: a Porphyry-Related Gold Deposit, Lander County, Nevada, in Buffa, R. And Coyner, A., Eds., Geology and Ore Deposits of the Great Basin - Field Trip Guidebook Compendium, The Geological Society of Nevada, Reno, p. 969-987.

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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.