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Doby George Deposit

Past Producer in Elko county in Nevada, United States with commodities Gold, Silver
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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 10310518
Record type Site
Current site name Doby George Deposit
Alternate or previous names Doby Deposit

Geographic coordinates

Geographic coordinates: -116.05993, 41.6629 (WGS84)
Elevation 2040
Relative position The mine is located about 2 miles east of Aura townsite.

Site location context

Political divisions (FIPS codes)

Elko(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Maggie Summit(quadrangle 1:24,000 scale)

Bull Run Mountains(quadrangle 1:100,000 scale)

McDermitt(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

South Fork Owyhee(hydrologic unit)

Middle Snake-Boise(hydrologic accounting unit)

Middle Snake(hydrologic subregion)

Pacific Northwest(hydrologic region)

Federal lands

Humboldt-Toiyabe National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Nevada Elko

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 044N 053E 31 34 SW4 Nevada

Comments on the location information

  • The mineralization occurs on both sides of the canyon south of a spring located a half mile due south of Columbia Summit.

Commodities

Commodity Importance
Gold Primary
Silver Primary

Comments on the commodity information

  • Commodity Info: Au:Ag ratios are strongly gold-biased, in contrast to the nearby Wood Gulch deposit
  • Ore Materials: native gold, electrum
  • Gangue Materials: quartz, sericite

Materials information

Materials Type of material
Gold Ore
Electrum Ore
Quartz Gangue
Sericite Gangue

Alteration

  • (Local) Host rocks are silicified and often sericitized. The diorite is weakly argillized in places

Mineral occurrence model information

Model code 173
USGS model code 26a.1
Deposit model name Sediment-hosted Au
Mark3 model number 17

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Sandstone
    Rock unit name Schoonover Formation (in part)
    Stratigraphic age (youngest) Mississippian
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone
    Rock type qualifier siliceous and calcareous
    Rock unit name Schoonover Formation (in part)
    Stratigraphic age (youngest) Mississippian
  • Host or associated Host
    Rock type Sedimentary Rock > Chemical Sediment > Chert
    Rock unit name Schoonover Formation (in part)
    Stratigraphic age (youngest) Mississippian
  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Stratigraphic age (youngest) Mesozoic
    Stratigraphic age (oldest) Tertiary
  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock type qualifier quartz
    Stratigraphic age (youngest) Mesozoic
    Stratigraphic age (oldest) Tertiary
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Pyroclastic Rock > Tuff
    Rock type qualifier dacitic
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Dacite
    Rock type qualifier tuff

Nearby scientific data

(1) -116.05993, 41.6629
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description In mineralized areas, numerous high-angle fault sets trend N, NE, and WNW, standing out topographically as prominent silicified ribs.

Ore body information

  • General form pods, irregular

Controls for ore emplacement

  • Ore mineralization is controlled by a combination of stratigraphy and structure.

Comments on the geologic information

  • Mineralization preceded the local volcanic event here, unlike at the nearby Wood Gulch deposit, where the mineralizing system affected the 40-million year old volcanics.

Economic information about the deposit and operations

Operation type Surface
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1983
Discoverer Felmont Oil Company

Mining district

District name Aura District

Land status

Ownership category National Forest
Area name Humboldt National Forest

Ownership information

  • Type Owner-Operator
    Owner Western Exploration and Development Ltd

Comments on the workings information

  • Surface exploration, drill roads

Comments on other economic factors

  • In 1994, the Doby George deposit was estimated to contain a remaining resource of 3300 kilotonnes of ore containing 6.7 tonnes of gold (Long and others, 1998). The total resource was reported as 250,000 troy ounces of gold in 1997.

Comments on development

  • The discovery claims were first staked and leases acquired in the Doby George area in 1983 by Felmont Oil Company, following the discovery of anomalous gold and trace elements as a result of a reconnaissance geochemical sampling program in the Maggie Summit area. More focused sampling and geologic mapping followed in 1984 resulting in a drilling program in 1985 after Homestake purchased Felmont. Ore grade intercepts were encountered early in the drilling, leading to an expanded drilling program in the late 1980s that delineated the three orebodies. Exploration and development proceeded under a 60/40 joint venture agreement between Homestake and Bargold in 1990. Independence Mining Company acquired the Doby George property in the early1990s, but by the end of 1995, Atlas Corp. had completed the purchase of the project from Independence Mining Co. Preliminary studies in 1995 indicated a reserve of 3.7 million tons at a grade of 0.060 opt Au. The three near-surface deposits that contain the majority of the indicated reserve still remain open. The Doby land position covers 14 square miles of public land. In addition to the main mineralization, five other zones of mineral potential have been identified. In early 1997, Atlas Corp. reported that it had granted an exclusive option to Aquaterre Mineral Development Ltd. to purchase Doby George for $3 million. Later in 1997, Atlas Corp. sold the Doby George property to Western Exploration and Development Ltd. for $1.6 million. Western had recently also acquired certain rights to the 84,000-acre IL Ranch in the Doby George area. Western was continuing exploration and development on the Doby George and surrounding property in 1999 (personal communication).

Reference information

Bibliographic references

  • Deposit

    Denver Mining Record, 7/23/95

  • Deposit

    Skillings Mining Review, 8/26/95

  • Deposit

    Northern Miner, 9/11/95

  • Deposit

    Miing Engineering, 10/1/95

  • Deposit

    Denver Mining Record, 11/15/95

  • Deposit

    Denver Mining Record, 1/29/97

  • Deposit

    Elko Daily Free Press, 10/11/97

  • Deposit

    Rocky Mountain Pay Dirt, June, 1989.

  • Deposit

    Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.

  • Deposit

    Western Exploration and Development Ltd., 1999, personal communication.

  • Deposit

    Baker, D.J., Stanley, W. R., and Dickerson, R.B., 1990, Geology of the Wood Gulch Mine Area and the Doby Prospect, Northern Independence Range, Elko County, Nevada, unpulished report, NBMG files

  • Deposit

    Western Exploration and Development Ltd., 1999, personal communication.

  • Deposit

    Rocky Mountain Pay Dirt, June, 1989.

General comments

Subject category Comment text
Deposit The deposit consists of three shallow oxidized pods of gold-silver mineralization with five other zones of anomalous gold mineralization identified. Fine-grained native gold occurs in a silicified matrix of siltstone and sandstone. Bedding in the host rocks strikes NNW to NE and dips gently west. Gold also occurs locally as inclusoins within goethite pseudomorphs after pyrite. The grade and thickness of the ore zones generally increases toward major structures, but small pods of mineralization traverse stratigraphic horizons with no apparent relationship to structure. Quartz veining typically accompanies mineralization and alteration. Host rocks are silicified and often sericitized. The mineralization predates the volcanic rocks present. Deeper drilling (to 1600 feet) encountered anomalous gold in calcareous rocks of the Schoonover Formation

Reporter information

Type Date Name Affiliation Comment
Reporter 01-JUN-2003 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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