Castle Prospect

Site Name

Primary: Castle Prospect
Secondary: Black Rock prospect
Secondary: Berg prospect
Secondary: Boss prospect

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Commodity

Primary: Gold
Primary: Silver
Secondary: Mercury
Tertiary: Antimony

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Location

State: Nevada
County: Esmeralda
District: Gilbert District (Desert 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: U. S. Bureau of Land Management

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Holdings

Not available

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Workings

Not available

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Ownership

Owner Name: Seabridge Gold, Inc.
Info Year: 2005

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: volcanic replacement along a fault-breccia, epithermal
Operation Type: Surface-Underground
Discovery Year: 1928
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 Hg

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Orebody

Form: tabular

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Structure

Type: L
Description: northeast- and northwest-trending fault zones.

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Alterations

Alteration Type: L
Alteration Text: silicification of volcanics and sedimentary rocks.

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Rocks

Name: Tuff
Role: Host
Description: andesite
Age Type: Host Rock
Age Young: Miocene

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

Name: Sedimentary Rock
Role: Host
Age Type: Host Rock
Age Young: Ordovician

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Cinnabar
Ore: Jarosite
Ore: Clay
Ore: Pyrite
Ore: Stibnite
Gangue: Chalcedony

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Comments

Comment (Workings): The deposit has been developed in the early days by a 60-foot inclined shaft with a 33-foot drift at its base. Also, more recently a trench, 10-foot adit, several diamond-drill holes and a small open pit are on the property.

Comment (Commodity): Gangue Materials: chalcedony, jarosite, clays, pyrite, stibnite

Comment (Commodity): Ore Materials: Gold, cinnabar

Comment (Identification): This record includes material from earlier records M241845, M241852, and M055246.

Comment (Location): The Castle property is located on the south edge of the Monte Cristo Range along U.S. Highway 95 about 22 miles west of Tonopah and 6 miles north of Blair Junction.

Comment (Development): The area was originally prospected for gold, but mercury was discovered and mined on a small scale in the area in the 1920s. There was some drilling in the area beginning in the 1940s and renewed in the 1970s. An NBMG field observation in 1982 noted recent drilling and road grading. In 1996, Fischer-Watt Gold Co. acquired Kennecott Exploration Co.'s 500-acre Castle Previous work by Kennecott defined a drill-indicated reserve of 3.7 million tons of rock grading 0.03 opt gold, (about 100,000 ounces of gold). The deposit reportedly is open in several directions. In 1998, Rayrock Yellowknife Resources Inc. acquired an option to earn a 75% interest in the Castle Gold deposit, where previous exploration by then had outlined a resource of 10 million tons of ore grading 0.03 opt gold. Rayrock's 1998 drilling confirmed the resource, and a preliminary valuation study indicated that the west half of this deposit, which is under shallow overburden, could be mined at a $300 per ounce gold price. In 1999 Cordilleran Exploration had filed a notice of intent to work on property in the area of the Castle prospect. In 2000, Seabridge Resources Inc. acquired the Castle/Black Rock gold project and reported at that time that it hosted a measured and indicated gold resource of 215,000 ounces, and a total gold resource in excess of 300,000 ounces. Seabridge commissioned an independent resource analysis by Bikerman Engineering & Technology Associates, Inc., that identified a measured and indicated gold resource of 13.64 million tons at an average grade of 0.016 opt Au (215,000 oz), based on 139 drill holes. An additional inferred gold resource of 8.76 million tons at 0.011 opt Au (93,000 oz) brings total gold resources to 308,000 oz. A separate geologic review of the project by Seabridge also identified three distinct new targets that could result in a significant increase in gold resources. In 2005, Seabridge was notified by Platte River Gold (US) that it has elected to terminate its right to earn an interest at the Company's 100% owned South Gilbert Project in Nevada.

Comment (Economic Factors): 1990: reserves of 637,500 tons grading 0.023 opt Au plus a geologic resource of 31,000 ounces of gold. 1996: 3.7 million tons of material grading 0.03 opt Au 1997: A resource of 10 million tons of material grading 0.03 opt Au. 1999: Measured and indicated reserves of 12.38 million tons of material grading 0.54 g/t (215,000 ounces of gold) plus an additional inferred resource of 7.95 million tons of material grading 0.37 g/t (93,000 ounces of gold) for a total inferred gold resource of 308,000 ounces, confirmed by an independent report in 2000.

Comment (Geology): Mineralization occurs along a fault zone in bleached, propylitic andesite, brecciated, fractured., and cut by silica veins with pyrite; brecciated zonesare filled with Fe-Mn oxide staining, drusy quartz.

Comment (Deposit): Epithermal gold mineralization at Castle is closely associated with northeast- and northwest-trending fault zones. Gold mineralization at Castle/Black Rock is concentrated in four identified zones (Castle, Black Rock, Berg, and Boss) in near-vertical structures within Tertiary volcanic and sedimentary rocks. Cinnabar occurs in the breccia vein in fractures and shears that cut the chalcedony. A small amount of stibnite occurs in a breccia zone in the slope above the mercury deposit. A short trench and adit southwest of the shaft explore a locally silicified rib of andesite tuff which trends N 65 W, dipping 70 NE, where cinnabar fills fractures and open spaces in silicified andesite. The deposit is hosted in the Ordovician Palmetto Formation beneath Tertiary volcanic cover. Four mineralized zones have been identified: Castle, Black Rock, Berg, and Boss.

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References

Reference (Deposit): Smith & Bentz, Field Examination, 23 September 1982

Reference (Deposit): Lawrence, E.F., 1963, NBMG Bull. 61, p. 64-65

Reference (Deposit): Silberman, M.L. and McKee, E.H., 1974, In NBMG Report 19, p. 71.

Reference (Deposit): Albers, J.P. and Stewart, J.H., 1972, Geology and Mineral Deposits of Esmeralda Co, Nev: N.B.M.G. Bull. 78, p. 67, Pl. 2.

Reference (Deposit): Tonopah Land Status, 1978

Reference (Deposit): NBMG Map 91, 1st, 2nd, 3rd editions

Reference (Deposit): NBMG MI-87 through MI-03

Reference (Deposit): Rayrock Resources Inc. news releases, 5/27/98, 11/13/98

Reference (Deposit): Denver Mining Record, 10/30/96

Reference (Deposit): Northern Miner, 11/4/96

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): BLM Claim Microfiche

Reference (Deposit): http://www.seabridgegold.net
URL: http://www.seabridgegold.net

Reference (Deposit): Amer. Mines (1989, 1990), 1989, 1990

Reference (Deposit): Seabridge Resources Inc. press release, 10/10/2000.

Reference (Deposit): Bailey, E.H., and Phoenix, D.A., 1944, Quicksilver Deposits in Nevada: Univ. Nev. Bull. Vol. 38, No. 5, Geol & Min. Ser. No 41, p.75.

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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.