Gold Bar Mine

Site Name

Primary: Gold Bar Mine
Secondary: Gold Bar Horst property
Secondary: Goldstone orebody
Secondary: Gold Ridge orebody
Secondary: Gold Pick orebody
Secondary: Gold Canyon orebody
Secondary: Cabin Creek orebody
Secondary: White Knight?s Olum claims

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Commodity

Primary: Silver
Primary: Gold
Tertiary: Antimony
Tertiary: Arsenic
Tertiary: Mercury
Tertiary: Barium-Barite
Tertiary: Manganese

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Location

State: Nevada
County: Eureka
District: Antelope 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: Atlas Precious Metals, Inc.

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminated
Operation Type: Surface
Year First Production: 1986
Year Last Production: 1996
Discovery Year: 1983
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: Sediment-hosted Au

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Orebody

Not available

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Structure

Type: L
Description: Paleozoic thrusting and folding and Tertiary age high angle faulting have affected rocks in the mine area. Limestone beds are gently folded along ENE-trending fold axes, forming anticlines and synclines that plunge 10-40 degrees to the east. The dominant Tertiary fault sets strike northwest and north-south; other sets strike east-northeast and northeast.

Type: R
Description: The Gold Bar deposits are located in a window of lower plate rocks below the Roberts Mountain Thrust and lying along the NW-trending Battle Mountain-Eureka Trend of mineral deposits.

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Alterations

Alteration Type: L
Alteration Text: Mineralization at Gold Bar is closely associated with major decalcification and to a lesser extent with silicification of host rocks and jasperoid development along high-angle structures. Also evident is remobilization of carbon and oxidation and redistribution. Minor bleaching, calcite veining, argillization. All alteration types occur mainly up dip from the feeder structure. The oxidation of pyrite and subsequent remobilization of iron oxides have produced spectacular brick-red to dark yellow brown banding in the oxidized, decalcified limestone. In many areas the ore exhibits intense liesegang banding. Most of the calcite veining is characterized by 0.1-30 cm veins located up dip from the orebody. Argillization is rare. Illitic clays have been locally altered to montmorillonite and allophane.

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Rocks

Name: Limestone
Role: Host
Description: fossiliferous
Age Type: Host Rock
Age Young: Early Devonian

Name: Tuff
Role: Associated
Description: agglomerate
Age Type: Associated Rock
Age in Years: 23.800000+-
Dating Method: K-Ar
Age Young: Late Oligocene

Name: Rhyolite
Role: Associated
Description: ash-flow tuff
Age Type: Associated Rock
Age in Years: 23.800000+-
Dating Method: K-Ar
Age Young: Late Oligocene

Name: Ash-Flow Tuff
Role: Associated
Description: rhyolitic
Age Type: Associated Rock
Age in Years: 23.800000+-
Dating Method: K-Ar
Age Young: Late Oligocene

Name: Mudstone
Role: Host
Description: thin-bedded, non-fossiliferous, limey
Age Type: Host Rock
Age Young: Middle Devonian

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

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Pyrite
Ore: Orpiment
Ore: Jasper
Ore: Stibiconite
Ore: Barite
Ore: Limonite
Ore: Hematite
Ore: Realgar
Gangue: Quartz
Gangue: Calcite

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Comments

Comment (Deposit): The Gold Bar deposits occur along the crest of a large east-west-trending antiform in thin-bedded lower plate carbonate rocks, where mineralizatoin was localized by NW- and NE-trending structural conduits. The Gold Bar, Goldstone, and Gold Canyon orebodies are hosted by thin-bedded, non-fossiliferous limey mudstone of the Upper Denay Unit 2, and are higher grade, more stratabound, and have well-developed bedded jasperoids. The Gold Pick, Gold Ridge, and Cabin Creek orebodies are hosted by thin-bedded fossiliferous limestone of the Bartine Member of the McColley Canyon Formation, and are lower grade, more structurally controlled, and have spotty basal jasperoids. Petrographic data suggest that gold mineralization postdates silicification and is contemporaneous with, or immediately postdates, decalcification. Three ore types are known: 1) oxidized, 2) jasperoidal, and 3) carbonaceous. The orebody consists mainly of oxidized ore with small amounts of jasperoidal and carbonaceous ore. The carbonaceous ores are twice the grade of the oxide ores. The Gold Bar deposits are located on the crest of a NNW-trending horst of Lower Plate Devonian Limestone covered by a thin veneer of Quaternary gravels and Tertiary volcanics. Mineralization is controlled by a NNW-trending fault and structural intersections with NE-trending cross faults. The recently discovered Millsite deposit lies 1000 feet WNW of the Gold Bar Mine and contains about 150,000 ounces gold at a grade of 0.09 opt gold (1.6 million tons @ 0.091 opt gold) at a depth of approximately 500 feet. The overall shape of the Gold Bar deposit is like a flattened cigar. Gold occurs as micron-sized grains in decalcified zones and along fractures in silicified zones. Petrographic examination and metallurgical testing indicate that the gold is not encapsulated by silica.

Comment (Development): Numerous companies explored the Roberts Mountains for precious metals deposits beginning in the 1960s. Regional reconnaissance exploration activity by Atlas Precious Metals discovered gold-anomalous jasperoid along the southwest flank of the Roberts Mountains in 1983. Atlas drilled 16 wide-spaced shallow exploration holes, one of which intersected thin gold mineralization (5 ft @ 0.13 opt gold). The following year, the Gold Bar deposit was discovered with the completion of hole number 28, which intersected 110 ft @ 0.138 opt gold starting at a depth of just 15 feet below the surface. Grid drilling of 270 holes on 100-foot centers began in the summer of 1984 and defined the Gold Bar deposit with a reserve of 2.8 million tons of ore grading 0.09 ounces of gold per ton. Mining began in 1986 with first production in 1987. Construction of the mill was completed in January, 1987 with an initial capacity of 1500 tpd., and was expanded in 1988 to its final capacity of 3000 tpd. It employed carbon-in-leach technology with gold recoveries of >90%. Atlas began reconnaissance mapping and sampling east of the mine in 1986, which resulted in the discovery of the nearby Goldstone, Gold Ridge, and Gold Pick orebodies in 1986-87. Subsequently, other companies identified additional nearby gold resources: the Cabin Creek resource was discovered in 1987 by American Copper and Nickel on claims joint-ventured with Nerco Minerals, and in 1988, Phelps Dodge Mining Company discovered the Gold Canyon deposit on claims leased from NL Baroid. Atlas acquired these two properties in 1991 and 1992, to add to the overall Gold Bar district inventory of resources. Mining at Gold Bar was completed in 1990, although stockpiled refractory ore from this deposit was processed through the mill after mining ceased. Production ceased in 1994. A total of over 286,000 ounces of gold was produced from the Gold Bar deposit between 1987 and 1996. Atlas negotiated a series of joint-venture agreements with other mining companies between 1994 and 1999. Homestake Mining Company entered into a joint venture in 1994 for exploration of the pediment area south and southeast of the Gold Bar mine. Homestake conducted CSAMT surveys and drilled 17 exploration holes on the area south of Gold Bar in 1995 and 1996. The joint venture was terminated in 1996. Atlas discovered the Millsite deposit in a down-faulted block west of the Gold Bar mine in 1995. Later that year, Vista Gold explored the immediate Gold Bar mine area as part of a proposed merger with Atlas, and partially drilled out the Millsite deposit. The proposed merger was terminated in 1997. American Barrick (Barrick Gold Exploration Inc.) acquired 90% of the Gold Bar properties in 1997 with a 2-year option to acquire the balance from Atlas. Barrick drilled a series of wide-spaced holes around the perimeter of the Millsite deposit in search of a >5 million ounce gold deposit. Barrick also drilled seven deep holes to the north. The Barrick joint venture was terminated in 1999, after which Vengold (American Bonanza Gold Mining Corp.) leased all of Atlas' holdings in the Roberts Mountains. American Bonanza reduced the size of its claim holdings in 2001 at which time White Knight staked two noncontiguous claim groups of the Gold Bar Horst claim block bordering the remaining claims at Gold Bar on the north and south. White Knight?s claims are in two noncontiguous blocks, covering the northern and southern projections of the ore-hosting horst beyond Bonanza Explorations' claims in the immediate Gold Bar mine area. The depth to bedrock under Quaternary gravels, as indicated by CSAMT and gravity surveys, and drilling, varies from less than 500 feet to greater than 1000 feet.

Comment (Economic Factors): In 1998, the combined geologic resource of the ?Gold Bar District? deposits was listed by Atlas geologists at 1.639 million troy ounces of gold contained in ore grading between 0.04 and 0.10 opt (French and others, 1998). Total cumulative production from the Gold Bar deposit through 1994 was 474,070 ounces of gold (NBMG MI-1996). Long and others estimated cumulative production from the Gold Bar mine between 1987 and 1995 to be 7,527,000 short tons of ore containing 482,815 ounces of gold and at least 3,000 ounces of silver. The remaining resource was estimated to be 6,047,000 short tons of ore grading 0.048 opt.(290,256 contained ounces); this resource includes Cabin Creek, Gold Canyon, Hunter, and Pot Canyon deposits. In 2006, White Knight Resources Ltd. reported an independent indicated resource estimate for its Gold Pick property in Eureka County, Nevada. The review verified an Indicated Resource of 320,900 ounces of gold in 7,874,000 tons at a grade of 0.041 oz/ton in the Gold Pick and Gold Ridge North deposits. Also in 2006, American Bonanza Gold Corp. announced that based on recent drill results at the Gold Bar Project, resources aggregate 1,622,500 tons @ 0.091 opt Au inferred. Gold Pick alone produced about 97,000 ounces from 1.4 million tons mined and processed at the Gold Bar mill from 1989-1994.

Comment (Geology): The deposits occur along the crest of a large east-west-trending antiform in thin-bedded lower plate carbonate rocks, where mineralizatoin was localized by NW- and NE-trending structural conduits. The Gold Bar, Goldstone, and Gold Canyon orebodies are hosted by thin-bedded, non-fossiliferous limey mudstone of the Upper Denay Unit 2, and are higher grade, more stratabound, and have well-developed bedded jasperoids. The Gold Pick, Gold Ridge, and Cabin Creek orebodies are hosted by thin-bedded fossiliferous limestone of the Bartine Member of the McColley Canyon Formation, and are lower grade, more structurally controlled, and have spotty basal jasperoids. Petrographic data suggest that gold mineralization postdates silicification and is contemporaneous with, or immediately postdates, decalcification. Three ore types are known: 1) oxidized, 2) jasperoidal, and 3) carbonaceous. The orebody consists mainly of oxidized ore with small amounts of jasperoidal and carbonaceous ore. The carbonaceous ores are twice the grade of the oxide ores. NW-trending horst of Lower Plate Devonian Carbonates which host the Gold Bar deposits. The claims are in two noncontiguous blocks, covering the northern and southern projections of the horst beyond Bonanza Explorations' claims in the immediate Gold Bar mine area. The depth to bedrock under Quarternary gravels, as indicated by CSAMT and gravity surveys, and drilling, varies from less than 500 feet to greater than 1000 feet. the Gold Bar deposit is located on the crest of a NNW-trending horst of Lower Plate Devonian Limestone covered by a thin veneer of Quaternary gravels and Tertiary volcanics. Mineralization is controlled by a NNW-trending fault and structural intersections with NE-trending cross faults. The recently discovered Millsite deposit lies 1000 feet WNW of the Gold Bar Mine and contains about 150,000 ounces gold at a grade of 0.09 opt gold (1.6 million tons @ 0.091 opt gold) at a depth of approximately 500 feet. White Knight's claims border within 2000 feet of the Millsite deposit. The majority of previous drilling on the Gold Bar Horst property is less than 350 feet deep and did not encounter bedrock. One deeper drill hole (BGB37) on White Knight's claims north of the Millsite deposit encountered a mineralized jasperoid grading up to 150 ppb gold from 1160 feet to total depth at 1255 feet. This hole may be peripheral to significant gold mineralization. The target is a large blind Carlin-type deposit hosted in Devonian Denay Formation or underlying McColley Canyon Formation beneath gravel cover and a possible cap of Tertiary volcanics. A cap of Vinini Formation siliciclastics at the Roberts Mountains thrust fault occurs along the west edge of the south Olum block and may also occur in the north part of the north Olum claims, enhancing the potential for a major Carlin-style deposit. NNW to NW-trending horst-bounding faults and crosscutting NE-trending faults are likely feeder structures. The mineralizing structure at Gold Bar has little offset, suggesting that it is not a major structure. The master feeder fault (analogous to Post fault in northern Carlin trend) has not been tested. The Gold Bar deposit may itself be a satellite to the major deposit of the district which remains undiscovered beneath gravel cover, possibly along one of the major horst-bounding faults

Comment (Identification): The Gold Bar mine as herein described includes material from the combined Gold Bar (M242943), Goldstone (RE00275), Gold Ridge (RE00276), Gold Pick (RE00277), Gold Canyon (MP90058), and Cabin Creek deposits combined with new material. The Gold Bar orebody itself is separate from and about 10 km SW of the other 5 deposits, which are concentrated in one area within about a 3 km radius.

Comment (Location): The Gold Bar Horst property consists of 183 unpatented claims (3,707 acres) in two blocks covering the Gold Bar Mine and mill facility now owned by American Bonanza Explorations. The claims are located on the southwest flank of the Roberts Mountains.

Comment (Commodity): Gangue Materials: Calcite, quartz, hematite, limonite, clays, barite, Mn oxides, stibiconite in oxidized ore. Pyrite, calcite in jasperoidal ore. Orpiment an drealgar

Comment (Development): In 2005 American Bonanza Gold Corp.(95%) announced that recent drill results at the Gold Bar Project include 380-395 feet @ 0.019 opt Au (BZGB-2); 630-725 feet @ 0.017 opt Au (BZGB-4); 690-720 feet @ 0.046 opt Au (BZGB-7) and 615-695 feet @ 0.071 opt Au (BZGB-8). In 2006, White Knight Resources Inc. announced that recent drill results at the Gold Pick Project include 117.3-123.4 meters @ 0.033 opt Au (GPQ-11); 123.4-129.5 meters @ 0.031 opt Au (GPQ-12); 155.4-160 meters @ 0.012 opt Au (GPQ-15) and 160-167.6 meters @ 0.083 opt Au (GPQ- 16). (resource = 2,600,000 tons @ 0.063 opt Au) Also in 2006, American Bonanza Gold Corp. announced that based on recent drill results at the Gold Bar Project, resources aggregate 1,622,500 tons @ 0.091 opt Au inferred.

Comment (Commodity): Ore Materials: NATIVE GOLD

Comment (Workings): The mine is developed by open pits, a mill, haul roads, drill roads and pads.

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References

Reference (Deposit): NBMG, 1988, The Nevada Mineral Industry-1987, NBMG Special Publication Mi-1987.

Reference (Deposit): Unpublished draft report by Atlas Precious Metals, Inc., 1988, NBMG District File 106, Item 14.

Reference (Deposit): http://www.whiteknightres.com/s/GoldBarHorst.asp
URL: http://www.whiteknightres.com/s/GoldBarHorst.asp

Reference (Deposit): Masinter, R.A., 1991, Zoning of Altered Wall Rock and Spatial Relations to Gold Ore, Gold Bar Mine, Nevada, in Raines, G.L., et al., eds. Geology and Ore Deposits of the Great Basin, the Geological Society of Nevada, Reno, p. 701-703.

Reference (Deposit): American Bonanza Gold Corp.Press Release: December 1, 2005

Reference (Deposit): Atlas Corporation, 1989, Annual Report for Fiscal Year Ended June 30, 1989.

Reference (Deposit): Atlas Corporation, 1990, Annual Report Form 10-K for Fiscal Year ended June 30, 1990.

Reference (Deposit): Atlas Corporation, 1991, Annual Report For Fiscal Year ended June 30, 1991.

Reference (Deposit): Atlas Corporation, 1992, Annual Report for Fiscal Year ended June 30, 1992.

Reference (Deposit): Final Environmental Assessment - Proposed Gold Bar Expansion Project (NV64-EA9-74), Bureau of Land Management, November 29, 1989.

Reference (Deposit): Broili, C., et al., 1988, Geology and Gold Mineralization of the Gold Bar Deposit, Eureka County, Nevada, in Schafer, R.W., et al., eds., Bulk Mineable Precious Metal Deposits of the Western United States, the Geological Society of Nevada, Reno, p. 57-72.

Reference (Deposit): NBMG MI-97.

Reference (Deposit): Geology and Mineralization of the Gold Bar District, Southern Roberts Mountains, Eureka County, Nevada, 1998, French, G.M., Fenne, F.K., Maus, D.A., Rennebaum, T.D., and Jennings, T.A., in Sediment-hosted Gold Deposits of the Eureka (Ruby Hill Mine) and Gold Bar Districts, East-Central Nevada, Geological Society of Nevada Special Publication No., 27, 1998 Spring Field Trip Guidebook.

Reference (Deposit): NBMG Mining District File 106, Numerous press clippings.

Reference (Deposit): Bonham, H.F., 1989, Bulk-Mineable Precious-Metal Deposits and Prospects in Nevada, NBMG Map 91.

Reference (Deposit): Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.

Reference (Deposit): Tingley and Smith, 1983, Results of geochemical sampling within the Shoshone-Eureka Resource Area, Eureka, Lander, and Nye Counties, Nevada: NBMG OFR 83-4.

Reference (Deposit): Tingley and Smith, 1983, A Mineral Inventory of the Shoshone-Eureka Resource Area, Battle Mountain District, Nevada: NBMG OFR 83-3.

Reference (Deposit): NBMG, 1991, The Nevada Mineral Industry-1990, NBMG Special Publication Mi-1990.

Reference (Deposit): Atlas Corporation, 1985, Annual Report for Fiscal Year ended June 30, 1985.

Reference (Deposit): Atlas Corporation, 1987, Annual Report for Fiscal Year ended June 30, 1987.

Reference (Deposit): Atlas Corporation, 1986, Annual Report for Fiscal Year ended June 30, 1986.

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

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

Reference (Deposit): Atlas Corporation, 1988, Annual Report for Fiscal Year ended June 30, 1988.

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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.