Rosebud Gold Mine

Site Name

Primary: Rosebud Gold Mine
Secondary: Dozer Hill Deposit
Secondary: Dreamland South ore zone
Secondary: Dreamland East ore zone
Secondary: Dreamland North ore zone
Secondary: NBMG sample sites 1798 and 1799
Secondary: Portal No. 1
Secondary: Portal No. 2
Secondary: East Dreamland target
Secondary: North Kamma target
Secondary: Schoolbus Canyon target
Secondary: Short Shot target
Secondary: White Alps target
Secondary: Wildrose target

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Commodity

Primary: Gold
Primary: Silver
Tertiary: Mercury
Tertiary: Antimony
Tertiary: Selenium
Tertiary: Barium-Barite
Tertiary: Copper
Tertiary: Arsenic

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Location

State: Nevada
County: Pershing
District: Rosebud 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: Winnemucca BLM District

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: John Dekinder And I. Swycaffer
Years: 1981 -

Owner Name: Equinox Resources Ltd
Years: 1985 -

Owner Name: Equinox (100%) (Co. Bought Lac Minerals' 51% Interest In July 1993.)

Owner Name: Lac Minerals

Owner Name: Rosebud Mining Company, LLC., a joint-venture: Newmont Gold Corporation
Percent: 50.00
Info Year: 2002

Owner Name: Rosebud Mining Company, LLC., a joint-venture: Hecla Mining Company
Percent: 50.00
Info Year: 2002

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: Hot springs Au-Ag; volcanic-hosted, low sulfidation, epithermal Au_Ag
Operation Type: Surface-Underground
Year First Production: 1908
Year Last Production: 2000
Discovery Year: 1989
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

Name: Rosebud Prospect

Name: Rosebud Deposit
Form: tabular

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Structure

Type: R
Description: The structural setting in the Rosebud Deposit area is dominated by the northeast trending Cave fault and the east-west trending South Ridge fault. The Cave fault is a regional structure that strikes from N50?E to N60?E and dips between 25? to 30? to the northwest. Stratigraphic offset across the Cave fault displays up to 2,000 feet of apparent normal displacement.

Type: L
Description: The Rosebud shear zone strikes N60E and has 5000 ft.of left lateral displacement. The South Ridge fault strikes E-W and dips 25 to 45 to the north.

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Alterations

Alteration Type: L
Alteration Text: Volcanic rocks in the mine area have been bleached, clay-altered (argillized, illite formed), sericitized, and locally silicified.

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Rocks

Name: Metasedimentary Rock
Role: Host
Age Type: Host Rock
Age Young: Early Jurassic
Age Old: Late Triassic

Name: Pyroclastic Rock
Role: Host
Age Type: Host Rock
Age Young: Miocene

Name: Rhyolite
Role: Host
Age Type: Host Rock
Age Young: Miocene

Name: Quartz Latite
Role: Host
Age Type: Host Rock
Age Young: Miocene

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Analytical Data

Analytical Data: 0.11 oz/st Au, up to 7.5 oz/st Ag from jasperoid zone sample
Analytical Data: Sample 1798 of kaolinized rhyolite breccia with limonite in vugs contains 1% Fe, 0.05% Mg, 0.05% Ca, 0.1% Ti, 15 ppm Mn, 1.5 ppm Ag, 0.2 ppm Au (by AA analysis), 20 ppm B, 500 ppm Ba, 1.5 ppm Be, 15 ppm Cu, 10 ppm Pb, 150 ppm Sr, 100 ppm Zr. Sample 1799 of rhyolite breccia, iron oxides, quartz with minor sulfides contains 3% Fe 0.07 Mg, 0.07% Ti, 15 ppm Mn, 3 ppm Ag, 500 ppm As, 20 ppm B, 500 ppm Ba, 2 ppm Be, 5 ppm Cu, 5 ppm Ni, 10 ppm Pb, 5 ppm Sc, 500 ppm Sr, 20 ppm V, 10 ppm Y, 150 ppm Zr, and also 0.1 ppm Au (by AA analysis)

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Materials

Ore: Electrum
Ore: Silver
Gangue: Limonite
Gangue: Barite
Gangue: Stibnite
Gangue: Marcasite
Gangue: Pyrite
Gangue: Calcite
Gangue: Quartz
Gangue: Jarosite

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Comments

Comment (Identification): This record includes all material from MRDS record M242759 and M242747 which should be deleted from the database. This deposit should not be confused with the historic Rosebud (Brown Palace) mine (MRDS record M242761) which lies about 1500 m to the NW or with the historic Dreamland Mine (MRDS record M232547) which lies about 1000 m north.

Comment (Location): The Rosebud Mine is situated on the east flank of the Kamma Mountains, north of Rosebud Canyon, a few miles south-southeast of the Crofoot/Lewis Mine which lies to the north in Humboldt County. UTM is to central part of mined area above the North ore zone. UTMs to the Main Zone are 4517900N, 361800E. UTMs to the East Zone are 4518000N, 361300E.

Comment (Workings): Old adits and more recent surface exploration and underground workings. The current mine is developed by two adits and associated underground workings.

Comment (Commodity): Gangue Materials: quartz, calcite, pyrite, marcasite, stibnite, barite, limonite, jarosite.

Comment (Deposit): The deposit is generally hosted within a series of Tertiary (late Oligocene-age) volcanics and volcaniclastics, primarily rhyolitic to latitic in composition. The volcanic package unconformably overlies the Jurassic/Triassic-age metasedimentary basement, which is also host to precious metal mineralization. Structure and stratigraphy control precious-metal mineralization in the Rosebud Deposit. Mineralization occurs in tabular zones along and in the hanging wall of the moderately dipping South Ridge Fault, and in cross-cutting high-angle structures. Multiple stages of discontinuous stockwork quartz-calcite-clay gold and silver-bearing veins cut variably clay-altered, silicified, and sericitized Miocene volcanic rocks. Silicified and kaolinized fault breccias and discontinuous stockwork quartz-calcite-clay veins in rhyolite host the ore. Mineralization at Dozer Hill consists of a crude stockwork and microveining of quartz, calcite, clay, pyrite, and marcasite within bleached, clay-altered, sericitized, and locally silicified volcanic rocks. Three orebodies were mined underground. The east zone is tabular, approximately 400 ft. by 600 ft. in plan, and 15 to 45 feet thick. The zone dips slightly to the north, and is elongate in a northwest direction. Other prospects within the Rosebud property are the Dreamland, East Dreamland, North Kamma, Schoolbus Canyon, Short Shot, White Alps, and Wildrose prospects.

Comment (Development): The Rosebud District was discovered in 1906. From 1908-1947 it produced 3,775 ounces of gold and 116,293 ounces of silver, mostly from the Dreamland Mine. The area was also prospected and developed for mercury deposits (MRDS #M055453) from at least the 1940s through 1981. In 1985, Equinox Resources Ltd. staked 46 claims over gold-mineralized volcanic rocks and began an exploration program that included mapping and sampling, and later drilling. LAC Minerals Ltd.?s initial interest in the Rosebud District resulted from a regional evaluation in 1987. Beginning in 1988, Lac began to acquire a property position through claim staking and formation of a joint venture with Equinox Resources. Regional geologic mapping, rock chip and soil sampling geochemical surveys, and induced polarization and airborne mag surveys were conducted in 1988. The first drilling occurred in 1989 in the vicinity of the historic Dreamland Mine. The third hole of the program intersected 55 ft./0.12 opt Au. A VLF survey was conducted in 1989. During 1990, 111 core and reverse circulation drill holes were completed for a total of 86,332 ft., 75% in partial delineation of the Dozer Hill deposit, located about 3,000 feet south of the Dreamland Mine and the remainder in outlying target areas. A 25,000 ft. drill program was conducted in the second half of 1991. The last drill hole in 1992 did confirm the high-grade nature of Dozer Hill, returning a 100-foot intersection grading 1.1 oz. Au. Most of the drilling in 1992 occurred on the Far East zone. An independent pre-feasibility study completed in August 1992 recommended proceeding to a final feasibility and underground development program. The underground, high-grade gold operation opened as a 50/50 joint venture between Hecla and Santa Fe Pacific Gold Corporation (later to become part of Newmont). In 2002 the deposit and surrounding areawere controlled and operated by the Rosebud Mining Company, LLC., a joint-venture between Hecla Mining Company (50%) and Newmont Gold Corporation (50%). Hecla Mining Company was the manager of mining and exploration and Newmont Gold was manager of milling. The deposit was mined underground, predominantly by cut-and-fill methods. The ore was then transported to Newmont Gold's Twin Creeks Pi?on Mill for processing. Pre-production development began in October of 1996 with production beginning in February 1997. Mining continued through 2000 after which the mine was closed.

Comment (Geology): Dozer Hill is the rounded knob southeast of the historic Rosebud camp. It is a light-gray Tertiary rhyolite extensively altered along faults and fractures. The fissure vein varies in width and is brecciated and has wispy streaks of gray running through the matrix. An adit to the north was driven on a parallel fissure-filling vein of altered, iron-stained volcanic breccia with limonite filling some of the vuggy structure.

Comment (Economic Factors): Rosebud production through November 1999 consisted of 789,244 tons at an average grade of 0.442 Au oz/ton and 2.68 Ag oz/ton containing 348,898 gold ounces and 2,117,957 silver ounces. The remaining proven and probable reserve in 2000 consisted of 215,673 tons at an average grade of 0.323 Au oz/ton and 1.23 Ag oz/ton totaling 69,713 gold ounces and 264,432 silver ounces. Thje last year of production was 2000, with production in that year totalling 47,944 ounces of gold and 191,919 ounces of silver. Total Rosebud gold production was about 375,000 ounces. No remaining reserves or resources are reported.

Comment (Commodity): Ore Materials: electrum, aurian silver, selenides, sulfosalts

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References

Reference (Deposit): Kenner, K., 1992, Discovery and Geology of Gold Mineralization at the Rosebud Project, Pershing County, Nevada, oral presentation, the Geological Society of Nevada, Elko Chapter, December 16.

Reference (Deposit): Johnson, M., 1977, Geology and Mineral Deposits of Pershing County, Nevada, NBMG Bull 89, 115 pp.

Reference (Deposit): Walck, C. M., Bennett, R. E., Kuhl, T. O., and Kenner, K. L., 1993, Discovery and Geology of Gold Mineralization at the Rosebud Project, Pershing County, Nevada: Society for Mining, Metallurgy, and Exploration, Inc., Preprint No. 93-175, 4 pp.

Reference (Deposit): "Equinox to Buy Lac's Rosebud," The Northern Miner, May 17, 1993, p. 3.

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

Reference (Deposit): Crafford, A.E.J. (ed.), 2003, GSN Road Log 2, Interstate 80 Eastbound, Fernley (Exit 48) to Golconda (Exit 194).

Reference (Deposit): Quade, Jack, 1984, NBMG Field Examination on September 2 and sample analyses.

Reference (Deposit): Bonham, Garside, Jones, Papke, Quade, Tingley, 1985, A Mineral Inventory of the Paradise-Denio and Sonoma-Gerlach Resource Areas, Winnemucca District, Nevada, NBMG Open File Report 85-3.

Reference (Deposit): LAC Minerals Corp., 1991, Annual Report for 1990.

Reference (Deposit): "Equinox Expects Decision by Spring for Rosebud Work", The Northern Miner, January 20, 1992, p.17.

Reference (Deposit): Engineering and Mining Journal, March, 1933.

Reference (Deposit): "Rosebud Stepout Drilling Returns Erratic Values", The Northern Miner, December 14, 1992.

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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.