Unnamed

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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MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

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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