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Rat Deposit

Producer in White Pine county in Nevada, United States with commodities Gold, Mercury
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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 10310446
Record type Site
Current site name Rat Deposit
Alternate or previous names Rat Pit
Related records 10310383, 10310443, 10310444

Comments on the site identification

  • The Rat Deposit is part of Placer Dome?s Bald Mountain Mine project.

Geographic coordinates

Geographic coordinates: -115.547, 39.92381 (WGS84)
Elevation 2530
Relative position The mine area is located approximately 60 miles northwest of Ely, Nevada and 60 miles southeast of Elko, Nevada.

Site location context

Political divisions (FIPS codes)

White Pine(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Big Bald Mountain(quadrangle 1:24,000 scale)

Newark Lake(quadrangle 1:100,000 scale)

Ely(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Little Smoky-Newark Valleys(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 White Pine

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 024N 057E 20 29 Nevada

Comments on the location information

  • The Rat deposit is located in the southern part of the Bald Mountain district about 1.5 mile southeast of the RBM deposit and 1.5 mile southwest of the Top/Mahoney Canyon/Sage Flat deposit area.

Commodities

Commodity Importance
Gold Primary
Mercury Tertiary

Comments on the commodity information

  • Ore Materials: free gold
  • Gangue Materials: pyrite, clay, limonite, jasperoid, quartz

Materials information

Materials Type of material
Gold Ore
Pyrite Gangue
Clay Gangue
Limonite Gangue
Quartz Gangue

Alteration

  • (Local) The porphyry dikes were sericitized, argillized and silicified.

Mineral occurrence model information

Model code 75
USGS model code 19c
Deposit model name Distal disseminated Ag-Au
Mark3 model number 18

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone
    Rock type qualifier sandy
    Rock unit name Dunderburg Shale
    Stratigraphic age (youngest) Late Cambrian
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Dunderburg Shale
    Stratigraphic age (youngest) Late Cambrian
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock
    Rock type qualifier fine grained
    Rock unit name Dunderburg Shale
    Stratigraphic age (youngest) Late Cambrian
  • Host or associated Host
    Rock type Sedimentary Rock
    Rock type qualifier calcareous
    Rock unit name Hamburg Dolomite
    Stratigraphic age (youngest) Cambrian
  • Host or associated Associated
    Rock type Plutonic Rock > Porphyry
    Rock type qualifier quartz-feldspar porphyry stock with satellitic dikes and sills
    Rock unit name Bald Mountain Stock
    Stratigraphic age (youngest) Late Jurassic
    Chronological age 159

Economic information

Geologic structures

Type of structure Regional
Structure description The Bald Mountain district is located in an area of thinned crust along the eastern side of the Late Proterozoic rift that split the North American craton. It is also in the west-central portion of the Late Devonian-Early Mississippian Antler foreland basin, and near the eastern edge of deformation related to the late Paleozoic Humboldt orogeny To the west of the Bald Mountain district, geologic interpretations are dominated by recognition of Paleozoic deformation, whereas to the east, interpretations emphasize Mesozoic contraction and plutonism and Tertiary extension.
Type of structure Local
Structure description NW-striking normal faults that dip steeply west and east, with lesser N-striking faults.

Ore body information

  • General form tabular to irregular

Controls for ore emplacement

  • The ore is both structurally and stratigraphically controlled. Ore is controlled by NW-striking normal faults that dip steeply west and east, with oreshoots forming at intersections of NW- and N-striking faults. One rich orebody up to 15 meters thick was localized by favorable lithology in interbedded sandy siltstone and limestone in the lower Dunderburg.

Comments on the geologic information

  • The Rat deposit has a low to non-existent base metal signature with higher Hg, As, and Sb values.
    The Rat deposit is characterized by Au, As, and Sb; the deposits are Au rich, with high Au/Ag ratios, values of As to about 2,000 ppm and Sb as much as 1,300 ppm, and low base metals.

Economic information about the deposit and operations

Operation type Surface
Development status Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Year of first production 1993
Production years 1993-1996

Mining district

District name Bald Mountain District

Land status

Ownership category BLM Administrative Area
Area name Ely BLM district

Ownership information

  • Type Owner-Operator
    Owner Barrick Gold Corp.
    Year 2006

Comments on the workings information

  • open pit

Comments on other economic factors

  • Production from the Rat deposit as of the end of 1995 was about 3 million tons of ore grading 0.09 ounces of gold per ton for a total contained 270,000 ounces of gold. The orebody was nearing depletion at that time with about 100,000 tons of 0.10 opt ore remaining.

Comments on development

  • Placer Dome began exploration in the Bald Mountain mine area in 1977 and the Rat deposit was discovered by 1978. In 1993, mining started in the Rat pit.
    In 2006, Barrick Gold Corp. acquired the Rat property through its acquisition of Placer Dome U. S., Inc.

Reference information

Bibliographic references

  • Deposit

    NBMG mining district files 323, press clippings

  • Deposit

    NBMG, 1988, NBMG MI-1987.

  • Deposit

    GSN 1985 meeting and fall field trip road log

  • Deposit

    Adamson, T.J., 1987, in Bulk Mineable Precious Metal Deposits of the Western U.S., 1987 GSN, Field Trip Guidebook and Technical Volume.

  • Deposit

    NBMG, 1994, MI-1993

  • 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.

  • Deposit

    Nutt, C.J., Hofstra, A.H., Hart, K.S., and Mortensen, J.K., 2000, Structural setting and genesis of gold deposits in the Bald Mountain-Alligator Ridge area, east-central Nevada, in Cluer, J.K., Price, J.G., Struhsacker, E.M., Hardyman, R.F., and Morris, C.L., eds., Geology and Ore Deposits 2000: The Great Basin and Beyond: Geological Society of Nevada Symposium Proceedings, May 15-18, 2000, p. 513-537.

  • Deposit

    Hitchborn and others, 1996, Geology and Gold Deposits of the Bald Mountain Mining District, White Pine County, Nevada, in Geology and Ore Deposits of the American Cordillera Symposium Proceedings, eds. A. Coyner and P. Fahey.

  • Deposit

    The Geological Society of Nevada 1996 Spring Field trip, Geology and Gold Deposits of Eastern Nevada, GSN Special Publication No. 23.

  • Deposit

    BLM, 2004, Bald Mountain Mine Exploration Program Programmatic Environmental Assessment NV040-04-023, Case File # N78825.

General comments

Subject category Comment text
Deposit The deposit is hosted in the lowermost part of the Dunderberg Shale. Ore was structurally controlled and adjacent to and locally within NW-striking dikes of quartz-feldspar porphyry. Interbedded limestone and siltstone are altered to marble and hornfels adjacent to the dikes. Silicification and decalcification are concentrated in the lower Dunderberg above its contact with the underlying Hamburg, and in faults and fractures in the Dunderberg. The Hamburg is silicified along bedding and fracture networks in the Rat deposit. Pervasive sericitization and weak argillization (mainly supergene) affected the dike, and spotty silicification is along the margins of the dike and in the adjacent Dunderberg. Fine-grained disseminated gold is associated with silica, clay, carbonaceous material, iron oxides, and secondary iron-arsenic minerals. Ore zones are characterized by quartz veining, stockwork formation, and silicified breccia. The ore zone is overlain b a blanket of barren remobilized carbon.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-NOV-2004 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.

Maps centered on this site

Authoritative Nevada resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.