The Unnamed is a copper, nickel, and iron mine located in Alaska.
About the MRDS Data:
All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.
Mine Info
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Unnamed MRDS details
Site Name
Primary: Unnamed
Commodity
Primary: Copper
Primary: Nickel
Primary: Iron
Secondary: Chromium
Secondary: Bismuth
Location
State: Alaska
District: McGrath
Land Status
Not available
Holdings
Not available
Workings
Not available
Ownership
Not available
Production
Not available
Deposit
Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:
Physiography
Not available
Mineral Deposit Model
Model Name: Noril'sk Cu-Ni-PGE
Orebody
Not available
Structure
Not available
Alterations
Alteration Text: Chalcedonic, carbonate.
Rocks
Not available
Analytical Data
Not available
Materials
Ore: Chalcopyrite
Ore: Pyrite
Ore: Pyrrhotite
Gangue: Magnetite
Comments
Comment (Exploration): Status = Inactive
Comment (Deposit): Model Name = Disseminated copper-nickel-cobalt (Cox and Singer, 1986; model 5b).
Comment (Deposit): Other Comments = Similar to Roberts PGM (MG030) and Chip Loy (MG032) prospects in McGrath A-3 quadrangle.
Comment (Geology): Age = Sill assigned a Late Triassic age by Bundtzen, Harris, and Gilbert (1997).
Comment (Reference): Primary Reference = This description
Comment (Workings): Workings / Exploration = Surface samples contain up to 200 ppm copper, 600 ppm nickel, 100 ppm bismuth, and 1,000 ppm chromium (Bundtzen, Kline, and Clough, 1982). Anomalous copper and chromium values were found in stream sediment samples taken in the occurrence area (Reed and Elliott, 1968, OFR).
Comment (Geology): Geologic Description = This unnamed occurrence consists of disseminated sulfides in a differentiated picrite-diorite sill that intrudes highly altered chert, sandstone, and siltstone of the Middle Devonian to Permian Sheep Creek Formation, a unit of the Mystic subterrane (Bundtzen, Harris, and Gilbert, 1997). The 15- meter-thick, mafic sill trends roughly EW and dips about 35N. Exposures continue along strike for about 3 kilometers before dipping below talus cover on both ends. Locally, the sill has produced a large 150-meter-wide alteration area in the sedimentary rocks, which is composed of chalcedonic-carbonate replacement of both country rock and the sill itself. The differentiated sill is interpreted by Bundtzen, Harris, and Gilbert (1997) to be a feeder for mafic volcanism in the overlying Late Triassic to Lower Jurassic Tatina River Volcanics. Mineralization appears at the base of the sill, and consists of abundant magnetite, pyrite, pyrrhotite, and traces of chalcopyrite. The size of the mineralized area was not determined. Samples of the sill are composed of up to 50 percent coarse grained magnetite interlocked with silicate melt minerals of magmatic origin. Some network style pyrite-pyrrhotite-magnetite zones contain up to 200 ppm copper, 600 ppm nickel, 100 ppm bismuth, and 1,000 ppm chromium (Bundtzen, Kline, and Clough, 1982; Bundtzen, Harris, and Gilbert, 1997). Anomalous copper and chromium values were found in stream sediment samples taken in the area (Reed and Elliott, 1968, OFR).
References
Reference (Deposit): Reed, B.L., and Elliott, R.L., 1968, Results of stream sediment sampling in parts of the southern Alaska Range: U.S. Geological Survey Open-File Report, 9 pages, one sheet, 1:500,000 scale.
Reference (Deposit): Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary geologic map of the McGrath B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File report 149, 22 pages, one sheet, scale 1:63,360.
Reference (Deposit): Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.
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