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Castle Prospect

Past Producer in Esmeralda county in Nevada, United States with commodities Gold, Silver, Mercury, Antimony
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Ownership information
  19. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10310346
MRDS ID M241845
Record type Site
Current site name Castle Prospect
Alternate or previous names Black Rock prospect, Berg prospect, Boss prospect
Related records 10046652

Comments on the site identification

  • This record includes material from earlier records M241845, M241852, and M055246.

Geographic coordinates

Geographic coordinates: -117.74676, 38.08549 (WGS84)
Elevation 1770
Relative position 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.

Site location context

Political divisions (FIPS codes)

Esmeralda(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Devils Gate(quadrangle 1:24,000 scale)

Tonopah(quadrangle 1:100,000 scale)

Tonopah(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Southern Big Smoky Valley(hydrologic unit)

Central Nevada Desert Basins(hydrologic accounting unit)

Central Nevada Desert Basins(hydrologic subregion)

Great Basin(hydrologic region)

Federal lands

Bureau of Land Management(Bureau of Land Management NV)

Bureau of Land Management NV BLM(Type of land area)

BLM(Federal land areas administered by BLM)

Geographic areas

Country State County
United States Nevada Esmeralda

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 003N 038.5E 33 Nevada
Mount Diablo 003N 039E 29, 30, 31, 32 Nevada

Comments on the location information

  • 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.

Commodities

Commodity Importance
Gold Primary
Silver Primary
Mercury Secondary
Antimony Critical Tertiary

Comments on the commodity information

  • Ore Materials: Gold, cinnabar
  • Gangue Materials: chalcedony, jarosite, clays, pyrite, stibnite

Materials information

Materials Type of material
Gold Ore
Cinnabar Ore
Jarosite Ore
Clay Ore
Pyrite Ore
Stibnite Ore
Chalcedony Gangue

Alteration

  • (Local) silicification of volcanics and sedimentary rocks.

Mineral occurrence model information

Model code 177
USGS model code 27a
Deposit model name Hot-spring Hg

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock
    Rock unit name Palmetto Formation
    Stratigraphic age (youngest) Ordovician
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Rock unit name GILBERT ANDESITE
    Stratigraphic age (youngest) Miocene
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Pyroclastic Rock > Tuff
    Rock type qualifier andesite
    Rock unit name GILBERT ANDESITE
    Stratigraphic age (youngest) Miocene
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Pyroclastic Rock > Tuff
    Rock type qualifier rhyolite

Nearby scientific data

(1) -117.74676, 38.08549
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description northeast- and northwest-trending fault zones.

Ore body information

  • General form tabular

Controls for ore emplacement

  • Ore deposition was controlled by brecciated zones along northeast- and northwest-trending fault zones.

Comments on the geologic information

  • 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.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1928

Mining district

District name Gilbert District (Desert District)

Land status

Ownership category BLM Administrative Area
Area name U. S. Bureau of Land Management\n

Ownership information

  • Type Owner-Operator
    Owner Seabridge Gold, Inc.
    Year 2005

Comments on the workings information

  • 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.

Comments on other 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.

Comments on 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.

Reference information

Bibliographic references

General comments

Subject category Comment text
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.

Reporter information

Type Date Name Affiliation Comment
Reporter 27-JUN-2002 LaPointe, D.D. Nevada Bureau of Mines and Geology
Editor 01-SEP-2007 Schruben, Paul G. U.S. Geological Survey Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

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Authoritative Nevada resources

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