Big Mike Copper Mine

Site Name

Primary: Big Mike Copper Mine
Secondary: NBMG Sample Site 2342

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Commodity

Primary: Copper
Tertiary: Silver
Tertiary: Zinc
Tertiary: Cobalt

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Location

State: Nevada
County: Pershing
District: Tobin and Sonoma Range area

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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

Type: Underground

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Ownership

Owner Name: Ranchers Exploration and Development Corp.
Company ID: 2600088
Percent: 100.0
Home Office: New Mexico

Owner Name: Ranchers Exploration, Hecla Mining Co.

Owner Name: GoldSpring, Inc.
Info Year: 2006

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: volcanogenic massive sulfide deposit.
Operation Type: Surface
Year First Production: 1966
Year Last Production: 1979
Discovery Year: 1930
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: Massive sulfide, Cyprus

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Orebody

Form: stratiform

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Structure

Not available

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Alterations

Not available

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Rocks

Name: Argillite
Role: Host
Description: cherty, carbonaceous
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

Name: Greenstone
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

Name: Sedimentary Rock
Role: Host
Description: turbidite
Age Type: Host Rock
Age Young: Early Permian
Age Old: Middle Pennsylvanian

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Analytical Data

Analytical Data: Sample 2342 of massive sulfide ore contains +20 % Re, 0.02 % Mg, 0.05 % Ca, 20 % Mn, 100 ppm Ag, 200 ppm B, 100 ppm Ba, +2000 ppm Co, +20000 ppm Cu, 20 ppm Mo, 100 ppm Ni, 70 ppm Pb, 1500 ppm Zn, and 10 ppm Zr

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Materials

Ore: Chalcopyrite
Ore: Bornite
Ore: Digenite
Ore: Tenorite
Ore: Cuprite
Ore: Sphalerite
Gangue: Pyrite

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Comments

Comment (Deposit): Big Mike is a high-grade, low tonnage, cupriferous pyrite volcanogenic stratiform massive sulfide deposit. It consists of a massive lens that occurs entirely within a thin cherty carbonaceous argillite. A stringer zone occurs in the footwall pillow basalt and a minor stringer zone occurs north of the massive lens in the hanging wall pillow basalt. Much of the dump material and pit wall consists of pillow lava, chert and argillite with varying amounts of limonite gossan and oxide copper minerals. The main deposit is volcanogenic massive sulfide of the hot springs type which occurs in the Havallah sequence. This is a thick greenstone complex in the Pumpernickel formation. When discovered the deposit consisted of a secondarily enriched pod of nearly massive copper and iron sulfides enveloped by altered rock containing zones and disseminations of secondary copper mineralization. The mineralogy is complex as various secondary effects are apparent. The structure of the area is also complex though the deformation of the Big Mike area is not so severe as other parts of the Havallah sequence. A shear zone runs through the Big Mike pit and extends approximately 1,000 feet in the south east and northwest directions away from the pit. This is also the general strike of the area with dips 40 to 60 degrees to the north east. This shear zone may be an indicator of further deposits. Five target areas have been identified for additional exploration on and adjacent to the Big Mike property. These targets show potential to extend the existing ore zone and for additional ore bodies.

Comment (Development): Copper occurrences were known in the area at about the turn of the last century. The project area was claimed in the early 1900s by the Foster family, but very little exploration was done and no development work was done. In 1966, Mr Clair Chamberlain optioned the property and undertook a sampling program. As a result of the sampling, some copper oxide ore was shipped to ASARCO in Tacoma, Washington. From this work the Big Mike Corporation was formed to develop and exploit the copper oxide ore by heap leaching. A small pad was developed and copper precipitate was produced. In 1967, the Big Mike Corporation entered into a joint venture with Cerro Corporation to explore the property further and this led to the discovery of a high grade copper sulfide orebody. By 1970, Ranchers? Exploration and Development Corporation acquired the property from Cerro Corporation and confirmed the sulfide orebody, which was rapidly developed via an open pit. In fact all the high grade ore was mined and directly shipped to smelters in 1970. The remaining oxide ore and the mixed and low grade sulfide ore was crushed for heap leaching. In the pit, similar low grade ore was blasted from the walls of the pit for leaching in the bottom of the pit. Heap leaching was carried out during two periods, from 1971 to 1974 and then 1978 to 1979. Both periods were curtailed by low copper prices. In 1979 Ranchers abandoned the claims. The claims were subsequently staked and reclaimed by WR & A. Big Mike Limited Partnership (BMLP) purchased the claims from WR & A., in 1988. During the period from 1988 to 1992 BMLP undertook project studies to establish reserves, identify a treatment method, and gain environmental permits to develop the project. A considerable amount of work was done, but the project did not get underway. John Cook and Dan Mackie examined data from the project in the spring of 1997 and concluded that it would be suitable for continuous vat leaching with the EcoVat. After this work an option agreement was entered into. GoldSpring, Inc. acquired 100% of this project. Th current Big Mike project is an oxide copper recovery project with the copper oxides remaining from a previous rich sulfide operation. The property also has exploration potential for further copper oxides and copper sulfides In 2005, GoldSpring, Inc. signed a memorandum of understanding with MBMI Resources Inc. to acquire a 50% interest in the 310-acre Big Mike copper property located 32 miles south of Winnemucca. Big Mike is a volcanogenic massive sulfide deposit that consisted of a secondarily-enriched pod of massive copper and iron sulfides enveloped by altered rock containing zones and disseminations of secondary copper mineralization. Ranchers Exploration and Development Co. produced 25 million pounds of copper from direct-shipping, high-grade copper sulfide ore from this property in 1970. Five target areas have been identified for additional exploration on and adjacent to the Big Mike property.

Comment (Commodity): Ore Materials: chalcopyrite, bornite, digenite, tenorite, cuprite, sphalerite

Comment (Commodity): Gangue Materials: pyrite, iron oxide

Comment (Workings): open pit mine of moderate size, dumps, core storage building (walls missing with thousands of meters of core inside-1980s).

Comment (Economic Factors): Ranchers Exploration and Development Co. produced 25 million pounds of copper from direct-shipping, high-grade copper sulfide ore from this property in 1970. The original estimates of reserves and resources were done by Ranchers. During the period from 1970 to 1979 Ranchers removed approximately 26 million pounds of copper in all forms. This was from an original estimate of 51 million pounds of copper. BMLP recalculated the reserves and resources from a re-examination of the Ranchers work and a sampling program on the broken ore remaining. A technical report available on the Goldspring website, 2006 reports the following mineable reserves on the Big Mike mine site. On Heap 319,000 tons of ore at 1.32%, 8,400,000 pounds of copper In Pit 640,000 tons of ore at 1.01%, 12,900,000 pounds of copper Dumps 134,000 tons of ore at 0.60%, 1,600,000 pounds of copper Pit Walls 103, 000tons of ore at 1.06%, 2,200,000 pounds of copper TOTAL 1,196,000 tons of ore at 1.05 % average grade, 25,100,000 mineable pounds of copper

Comment (Identification): This is an updated version of record M060499 for the Big Mike Copper Mine. The current record includes all material from the earlier record plus additional updated material.

Comment (Location): The Big Mike Project consists of 17 unpatented lode mining claims and 1 placer mining claim covering a total of 310 acres located south of Panther Canyon and 6 1/2 miles southeast of Leach Hot Springs.

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References

Reference (Deposit): Techncial report at http://www.goldspring.us/mike.htm
URL: http://www.goldspring.us/mike.htm

Reference (Deposit): NBMG Staff, 1985, NBMG 85-3.

Reference (Deposit): Garside, L.J., 11 Sep 84, NBMG Field Examination and sample analysis.

Reference (Deposit): Rye, R.O., et al., 1984, Economic Geology, volume 79, p. 124-140.

Reference (Deposit): Engineering Mining Journal, 1971, 1973.

Reference (Deposit): Johnson, Maureen G., 1977, Geology and Mineral Deposits of Pershing County, Nevada' Reno: Nevada Bureau of Mines and Geology Bulletin 89, 115p.

Reference (Deposit): Intermountain Pay Dirt, Oct 1984,

Reference (Deposit): Snyder, W.S., 1977, Ms Thesis, University Of Nevada-Reno.

Reference (Deposit): Hart, D.D., 1977, Unpublished report on ores of Big Mike Mine, NBMG Mining District File 270, Item # 11.

Reference (Deposit): Carithers, W. and Forbes, J.M., 1969, Unpublished report on Big Mike Property; NBMG File 270, Items #12 and #13.

Reference (Deposit): GoldSpring, Inc. press release, 11/1/05.

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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.