Spring Valley Project

Site Name

Primary: Spring Valley Project
Secondary: Spring Valley Placers
Secondary: Horseshoe Mine

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Commodity

Primary: Gold
Secondary: Silver

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Location

State: Nevada
County: Pershing
District: Fitting 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: Midway Gold Corporation
Info Year: 2005

Owner Name: Atolia Minerals, Inc. (Sept 1984)
Info Year: 1984

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: placer; breccia and vein-stockwork system
Operation Type: Surface
Year First Production: 1875
Year Last Production: 1984
Discovery Year: 1875
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: Placer Au-PGE
Model Name: Epithermal vein, Comstock

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Orebody

Form: channels, blanket

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Structure

Not available

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Alterations

Not available

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Rocks

Name: Rhyolite
Role: Host
Age Type: Host Rock
Age Young: Late Permian
Age Old: Early Triassic

Name: Gravel
Role: Host
Age Type: Host Rock
Age Young: Quaternary

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Analytical Data

Not available

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Materials

Ore: Gold
Gangue: Clay
Gangue: Gravel

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Comments

Comment (Development): Placer gold was discovered in 1875. Chinese miners extensively worked the deposits from 1880-1895. The gravels in the lower valley were dredged from 1910-1914, and reworked locally by hand in the 1920s and 1930s. The placers were mined by Spring Valley Dredging Co. in 1949. The placer mining area was idle when examined in Sept. 1984, but there were obvious signs of recent activity including relatively new mining equipment and trucks on property. One area of the property in sec 36 was listed as active (the Horseshoe mine) in 1984, owned by Duane E. Bender, Dan Selzer, and Walter Martin of Lovelock, NV. Since the 1970s, exploration on the Spring Valley Property by Kennecott Exploration, Ltd., and more recently, by Echo Bay Exploration, Inc., has identified several mineralized intervals within the rhyolite volcanic and volcaniclastic assemblage. To date, a total of 23 reverse circulation (RC) and two core holes have been completed on the Spring Valley Property. Echo Bay and Kennecott drilled the initial 25 holes on the property. Midway Gold has completed 31 drill holes since it acquired the project in 2003. Of the 52 reverse circulation (RC) and four core holes completed to date, forty holes have encountered gold grades greater than 0.01 oz/st (0.3 g/t) gold. Economic gold grades over significant thicknesses have been encountered in 19 drill holes. Preliminary metallurgical testing on drill cutting composites indicates gold recoveries of 75 to 95 percent. Due to the coarse nature of gold at Spring Valley, metallic screen preparation of samples is required to provide representative analyses. In addition to the Pond zone and its extensions, five new targets were identified through geologic mapping, CSAMT surveys, and geochemical sampling. These new targets have the potential to substantially increase the known gold inventory at Spring Valley. Midway began testing these targets with a 10,000 foot drill program in October, 2004. Preliminary results near the end of 2004 about halfway through this drilling project indicate the discovery of a new gold-bearing zone 500 feet east of the Pond zone, in a shallower structural block. The new zone consists of 60 feet of 0.034 ounces per ton (opt) gold (18.3m of 1.16 grams per ton (g/t) gold) in an angle hole in a rhyolite sill with quartz-tourmaline veins. A second drill hole encountered 5 feet of 0.076 opt gold (1.5 m of 2.6 g/t gold) at the alluvium-bedrock contact suggesting a nearby buried gold source. A third drill hole encountered 50 feet of 0.62 opt silver (15.2m at 22g/t) and 10 feet of 0.018 opt gold in the edge of a newly identified breccia pipe 2000 feet east of the Pond zone. Additional drilling was planned in early 2005 to test some of the thicker breccia targets, which were not then accessible.

Comment (Economic Factors): Th placer mines were productive for the time intervals 1911-1914 and 1947-49, during which a total 2,000 ounces of placer gold production was reported. There was however considerably more gold produced than recorded, especially during the 1800s, and it is estimated that approximately 100,000 ounces of placer gold has been historically recovered from Spring Valley. The placer mined area transects the currently prospected Spring Valley lode silver-gold property. In 2006 Midway Gold Corp. announced recent drill results at the Spring Valley Project and reported a drill-indicated resource of 10,030,000 tons of material grading 0.024 ounces of gold measured and indicated.

Comment (Geology): The gravels in the lower canyon are 20-30 feet thick and contain gold in gravel horizons underlain by clay. Placer gold was derived from stringer zones in the Koipato Rhyolite.

Comment (Deposit): The Spring Valley Property hosts a buried vein-stockwork gold system hosted in Permo-Triassic Rochester Formation rhyolite beneath 50 to 200 feet of alluvial cover. There are several mineralized intervals within the rhyolite volcanic and volcaniclastic assemblage. Gold at Spring Valley is hosted by a buried breccia and vein-stockwork system hosted in Permo-Triassic Rochester Formation rhyolite beneath 50 to 200 feet of alluvial cover. The gold occurs in and around a volcanic breccia interpreted to be a diatreme vent, called the Pond zone. This discovery is open to the northwest, southwest, and east. Mineralization is in quartz-tourmaline stockwork veins cutting quartz-sericite altered breccias and rhyolite volcanic rock. Narrow high-grade quartz-tourmaline veins with grades of 1 ounce of gold per sort ton of ore (31g/t) have been discovered in and around the breccia pipes. Most of these zones are oxidized from a 400 to 700 foot depth. The placer gravels in the lower canyon are 20-30 feet thick and contain gold in gravel horizons underlain by clay.

Comment (Identification): This is an updated version of record M060380 for the historic Spring Valley Placers. The current record includes the Spring Valley lode exploration project.

Comment (Location): The Spring Valley placer mines are located in Spring Valley about 8 miles due east of Oreana, on the west side of Buena Vista Valley. The more recently prospected Spring Valley lode silver-gold property includes 25 unpatented mining claims located in Spring Valley Canyon about three miles northeast and along strike from the Coeur- Rochester silver-gold mine.

Comment (Workings): Placer tailings, pits, ponds, mining equipment, recent drilling (2004)

Comment (Commodity): Ore Materials: coarse and some fine free gold

Comment (Commodity): Gangue Materials: gravels; clay

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References

Reference (Deposit): Midway Gold Corp. press release, Sept. 2006.

Reference (Deposit): website: http://www.midwaygold.com.
URL: http://www.midwaygold.com

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): Schrader, F.C., 1914, The Rochester Mining District, Nevada; USGS Bull. 580-M

Reference (Deposit): Vanderburg, 1936, Reconnaissance of Mining Districts in Pershing County, Nevada: USBM IC 6902

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

Reference (Deposit): Division of Mine Inspection, Aug 1985, Directory of Nevada Mine Operations Active During Calendar Year 1984.

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

Reference (Deposit): Bonham, H. F., Jr., 25 Sep 84, NBMG Field Examination of the Placers

Reference (Deposit): Vikre, P.G., 1978, Geology & and Silver Mineralization of the Rochester District, Pershing County, Nevada; Ph.D. Thesis Stanford Univ.

Reference (Deposit): Vanderburg, 1936, Placer Mining in Nevada; NBMG Bull. 30

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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.