RBM Deposit

Site Name

Primary: RBM Deposit
Secondary: Bald Mountain Mine project

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Commodity

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

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Location

State: Nevada
County: White Pine
District: Bald Mountain 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: Ely BLM district

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Barrick Gold Corp.
Info Year: 2006

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: sediment-hosted disseminated gold
Operation Type: Surface-Underground
Year First Production: 1988
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: Distal disseminated Ag-Au

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Orebody

Not available

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Structure

Type: L
Description: NW-striking normal faults that dip steeply west and east, with lesser N-striking faults.

Type: R
Description: To the west of the Bald Mountain district, geologic interpretations are dominated by recognition of Paleozoic deformation, whereas to the east, interpretations emphasize Mesozoic contraction and plutonism and Tertiary extension.

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Alterations

Alteration Type: L
Alteration Text: The porphyry dikes were sericitized, argillized and silicified. Intense argillic alteration almost totally obliterated the texture of the protolith host rock, and grades outward to phyllic alteration.

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Rocks

Role: Associated
Age Type: Associated Rock Unit
Age in Years: 159.000000+-
Age Young: Late Jurassic

Name: Porphyry
Role: Host
Description: quartz-feldspar porphyry stock with satellitic dikes and sills
Age Type: Host Rock
Age Young: Miocene

Role: Host
Age Type: Host Rock Unit
Age Young: Middle Ordovician
Age Old: Early Ordovician

Name: Sedimentary Rock
Role: Host
Description: calcareous
Age Type: Host Rock
Age Young: Cambrian
Age Old: Ordovician

Name: Clastic Sedimentary Rock
Role: Host
Description: fine grained
Age Type: Host Rock
Age Young: Cambrian
Age Old: Ordovician

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Sphalerite
Ore: Galena
Ore: Arsenopyrite
Ore: Marcasite
Ore: Quartz
Ore: Limonite
Ore: Clay
Ore: Chalcopyrite
Gangue: Pyrite

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Comments

Comment (Commodity): Ore Materials: free gold

Comment (Deposit): The RBM deposit is located along a NW-trending structural zone and consists of two main minerlized zones: the RBM main vein , which strikes N45W, and the RBM west vein, which strikes N75W. Dips are vertical to 60E. The West vein is oxidized near surface with a massive sulfide ore zone at depth consisting of pyrite, marcasite, arsenopyrite, galena, sphalerite, chalcopyrite, and possible tellurium-bearing sulfides. Sedimentary rocks at the deposit are fine-grained limestone, impure sandstone, quartzite, and siltstone of the Antelope Valley Formation and Eureka Quartzite. The sediments were intruded by quartz feldspar porphyry which has been altered. The quartz feldspar porphyry is present in the western portion of the deposit and hosts most of the gold mineralization. Faulted contacts betwen the sedimentary rocks and the dikes acte as conduits for mineralizing fluids. The RBM deposit was originally in the upper part of the Bald Mountain system above the Top deposit, and was subsequently downdropped along the Ruby listric fault to its present position. More than 1 km of gold-bearing rock between the RBM deposit and present day exposures of the originally underlying Top deposit was removed by erosion.

Comment (Development): Placer Dome began exploration in the Bald Mountain mine area in 1977 and the RBM deposit was among the earliest discoveries in the first year of exploration. The RBM deposit was placed into production late in 1988. In 2006, Barrick Gold Corp. acquired the RBM property through its acquisition of Placer Dome U. S., Inc.

Comment (Commodity): Gangue Materials: pyrite, clay, limonite, jasperoid, quartz, marcasite, arsenopyrite, galena, sphalerite, chalcopyrite, possible tellurium-bearing sulfides

Comment (Economic Factors): The oxide portion of the deposit was mined in 1989-1990. About 1.7 million tons of ore grading 0.065 ounces per ton was mined to a depth of 250 feet with a strip raio of 5.0:1.0.

Comment (Geology): The Top and RBM deposits both have high Cu, Zn, and Ag contents associated with gold mineralization as well as anomalous values in Bi, Hg, As, Sb, and tellurides.

Comment (Identification): The RBM Deposit is part of Placer Dome?s Bald Mountain Mine project.

Comment (Location): The RBM deposit is on the western edge of Bald Mountain, about midway between the 1-5 Pit area to the north and the Rat deposit to the south

Comment (Workings): open pit

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References

Reference (Deposit): NBMG Mining District Files 323, Press Clippings

Reference (Deposit): NBMG, 1988, NBMG MI-1987.

Reference (Deposit): GSN 1985 Meeting and Fall Field Trip Roadlog

Reference (Deposit): Adamson, T.J., 1987, in Bulk Mineable Precious Metal Deposits of the Western U.S., 1987 GSN, Field Trip Guidebook and Technical Volume.

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

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): Nutt, C.J., Hofstra, A.H., Hart, K.S., and Mortensen, J.K., 2000, Structural setting and genesis of gold deposits in the Bald Mountain-Alligator Ridge area, east-central Nevada, in Cluer, J.K., Price, J.G., Struhsacker, E.M., Hardyman, R.F., and Morris, C.L., eds., Geology and Ore Deposits 2000: The Great Basin and Beyond: Geological Society of Nevada Symposium Proceedings, May 15-18, 2000, p. 513-537.

Reference (Deposit): Hitchborn and others, 1996, Geology and Gold Deposits of the Bald Mountain Mining District, White Pine County, Nevada, in Geology and Ore Deposits of the American Cordillera Symposium Proceedings, eds. A. Coyner and P. Fahey.

Reference (Deposit): The Geological Society of Nevada 1996 Spring Field trip, Geology and Gold Deposits of Eastern Nevada, GSN Special Publication No. 23.

Reference (Deposit): BLM, 2004, Bald Mountain Mine Exploration Program Programmatic Environmental Assessment NV040-04-023, Case File # N78825.

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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.