Gold Hill Deposit

Site Name

Primary: Gold Hill Deposit

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Commodity

Primary: Gold
Primary: Silver
Tertiary: Arsenic
Tertiary: Tungsten
Tertiary: Antimony
Tertiary: Thallium
Tertiary: Mercury
Tertiary: Molybdenum
Tertiary: Fluorine-Fluorite
Tertiary: Manganese

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Location

State: Nevada
County: Nye
District: Round 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: Tonopah BLM Administration District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: optioned by Round Mountain Gold Corp., a joint venture between Kinross Gold Corporation and Barrick
Info Year: 2005

Owner Name: Nevada Star Resource Corp., (lessor)
Info Year: 2005

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: disseminations; veins; sheeted zones
Operation Type: Surface-Underground
Year First Production: 1910
Year Last Production: 1960
Discovery Year: 1910
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: Hot-spring Au-Ag

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Orebody

Form: tabular

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Structure

Type: L
Description: Northwest-striking faults and joints; a WNW-trending paleotopographic high, may represent the margin of buried caldera located SW of Round Mountain.

Type: R
Description: Ore deposits are localized by a NW-trending lineament.

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Alterations

Alteration Type: L
Alteration Text: Propylitization and argillization of host rocks are intense. Adularia replacement of K-feldspars and plagioclase is associated with ore. Plagioclase and groundmass are replaced with quartz and sericite. Within propylitically altered rock, biotite is partially or wholly altered to chlorite. Groundmass is altered to chlorite +/- clay +/- carbonate+/- epidote. Plagioclase phenocrysts are altered to sericite (illite) as small points, clots, and veinlets along cleavage planes. Argillically altered rock contains no unaltered biotite or plagioclase, both phases being altered to clay (illite, montmorillonite, kaolinite) and sericite. Groundmass is entirely composed of fine-grained clays and sericite. Quartz-adularia silicification is widespread along the veins. Degree of silicification, sericite + argillic alteration increases with (higher) elevation. Fine-grained secondary quartz has replaced original plagioclase feldspars, occurs as clots in the groundmass, and as hairline veinlets that lace the rock.

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Rocks

Name: Metasedimentary Rock
Role: Associated
Age Type: Associated Rock
Age Young: Permian

Name: Granite
Role: Associated
Age Type: Associated Rock
Age Young: Cretaceous

Name: Rhyolite
Role: Host
Description: ash-flow tuff
Age Type: Host Rock
Age in Years: 26.000000+-
Dating Method: K-Ar
Age Young: Late Oligocene

Name: Ash-Flow Tuff
Role: Host
Description: rhyolitic
Age Type: Host Rock
Age in Years: 26.000000+-
Dating Method: K-Ar
Age Young: Late Oligocene

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Realgar
Ore: Fluorite
Ore: Kaolinite
Ore: Montmorillonite
Ore: Illite
Ore: Jarosite
Ore: Alunite
Ore: Pyrite
Ore: Limonite
Ore: Hematite
Ore: Sericite
Ore: Adularia
Ore: Quartz
Ore: Pyrite
Ore: Electrum
Ore: Scorodite
Gangue: Clay

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Comments

Comment (Location): The Gold Hill Deposit is centered about 4 miles north of the town of Round Mountain.

Comment (Workings): Historic mining was conducted by underground developments. Major facilities at the currently proposed mine include two open pits of 380 acres and 105 acres in size and a heap leach pad of 280 acres.

Comment (Development): The first significant production in the Round Mountain district was principally from the Gold Hill Mine in the 1930s. There was later sporadic production between 1950 and 1964. Total production at Gold Hill was about 28,000 ounces. Grades are estimated to have been about 0.3 ounces of gold per ton. The property was controlled through much of the 1980s by Round Mountain Gold Corporation (RGMC), which was at that time a joint venture of Echo Bay Mining, Homestake, and Case Pomeroy. They conducted extensive exploration including surface mapping, geochemistry, geophysics and a structural evaluation. Their work culminated in drilling, preliminary metallurgical test work and a resource and economic evaluation. According to a 1988 report by Mine Development Associates, a mineral inventory of 3.1 million tons (2.8 million tonnes) grading 0.05 oz Au/ton (1.7 g Au/t) at a 0.025 oz Au/ton (0.85 g Au/t) cutoff was defined. Exploration work during the 1990s included additional geological mapping, surface sampling, geophysics, 100 drill holes by RMGC (both reverse circulation and core), 10 core holes completed by Nevada Star and the preparation of a digital database of all available exploration data. In 1995, Nevada Star staked 55 claims and acquired an option to purchase 53 additional claims in the Round Mountain Mining District, in consideration of $1,010,000 U.S. over 10? years. In a 2000 agreement, RMGC assumed the remaining payment obligations to the vendor and paid $275,000 to Nevada Star by 2005. Thereafter, RMGC will pay annual production royalties to Nevada Star. In 2003, Round Mountain Gold Corp. started the permitting process for a proposed mine at the Gold Hill property and continued drilling to define the gold deposit. The Gold Hill property is undergoing an EIS (Environmental Impact Study) which is expected to be completed in the Fall of 2005. Plant production is scheduled to start in the early spring of 2006. Higher-grade ore from the Gold Hill Project will be trucked to a mill at the existing Round Mountain Gold mine.

Comment (Economic Factors): There was a small amount of historic recorded production from 1910 to 1930. From 1930 to 1933, 94,500 tons of ore worth $700,000 was produced and from 1934 to 1942 ore valued at $217,000 was produced. Total recorded production from the historic Gold Hill property was about 28,000 ounces of gold from ore grading an estimated 0.3 ounces of gold per ton. From 1995 to 1998, RMGC reported a potential resource of 306,622 ounces of gold and 4,871,890 ounces of silver in the Gold Hill property. Subsequently, the reserves and resources were included as part of the overall Round Mountain Mine endowment.

Comment (Geology): A sequence of water-laid tuff, tuffaceous sandstone, conglomerate, and thinly laminated siltstone overlies the orebody.

Comment (Commodity): Ore Materials: free gold, electrum, auriferous pyrite

Comment (Commodity): Gangue Materials: clay minerals, quartz, adularia, sericite, hematite, limonite, manganese oxide, pyrite, alunite, jarosite, illite, montmorillonite, kaolinite, fluorite, realgar, scorodite

Comment (Deposit): The host rock at Gold Hill includes densely welded rhyolite tuff of the Mount Jefferson Caldera. The Mount Jefferson tuff overlies the Moores Creek tuff which in turn lies over the Round Mountain tuff, the host of the Round Mountain mine. These Tertiary volcanic rocks overlie a volcanic mega-breccia that, in turn, overlies Paleozoic metasediments. The youngest rock in the area is Quaternary-Tertiary pediment gravel. These units are generally composed of cobbles of the younger maroon tuff and are always completely barren of gold mineralization. Alteration in the area ranges from propylitic to argillic to advanced argillic to silicified. The gold mineralization is related to both quartz veining in argillized rock and silicification. The principal feature in the area is the Gold Hill vein and its sub-parallel veins. These all strike N75?W and dip variably, but steeply. In general, the veins dip southerly near the surface but dip back to the north at depth. These veins branch and coalesce and are banded quartz, but can also be composed of crushed quartz and rhyolite. Higher-grade pods generally exist where two periods of veining intersect, the entire zone is up to 500 ft wide and is 3,000 ft long, extending from beyond the range front fault on the west (where it remains open) to near the Toquima shaft on the east. The mineralization extends to the west of the range front fault where one hole hit approximately 80 ft of about 0.11 oz Au/ton.

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References

Reference (Deposit): Giancola, 1998

Reference (Deposit): Nevada Bureau of Mines and Geology, 1999, 2000, 2001, 2003.

Reference (Deposit): Kleinhampl and Ziony, 1984

Reference (Deposit): Kinross Gold Corp., 2004a

Reference (Deposit): United States Geological Survey, 1971a.

Reference (Deposit): United States Bureau of Mines, 1995

Reference (Deposit): United States Bureau of Land Management, 1978k

Reference (Deposit): Tingley, 1998

Reference (Deposit): Harding 2004c

Reference (Deposit): Nevada Star Resources Corp. Annual Report, 2004

Reference (Deposit): Nevada Star Resource Corp. website, Dec. 2005, http://www.nevadastar.com/s/GoldHillProject.asp
URL: http://www.nevadastar.com/s/GoldHillProject.asp

Reference (Deposit): Nevada Star Resource Corp. press release, 7/2/2003

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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.