Pyrrhotite

The Pyrrhotite is a nickel, iron, copper, and cobalt 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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Site Name

Primary: Pyrrhotite

Commodity

Primary: Nickel
Primary: Iron
Primary: Copper
Primary: Cobalt
Secondary: Zinc

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: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Polymetallic replacement

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: None.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Pyrrhotite
Ore: Pyrite
Gangue: Calcite

Comments

Comment (Exploration): Status = Inactive

Comment (Geology): Geologic Description = The Pyrrhotite occurrence consists of several semi-massive to massive pods of pyrrhotite and minor pyrite enclosed in banded hornfels and marble adjacent to a small stock of highly altered granodiorite porphyry. The host rocks are thermally altered marble and clastic sediments of the mid-Silurian Terra Cotta Mountains Sandstone, a unit of the Dillinger subterrane (Bundtzen and others, 1997). . Pyrrhotite occurs as disseminated grains in veinlets up to 8 centimeters thick, as semimassive to massive sulfide pods up to 30 centimeters thick, and as clots and crystals up to three centimeters across. Grab samples of pyrrhotite-rich sulfide mineralization collected during investigations by Anaconda Minerals Company contained up to 0.44 percent nickel and 460 ppm cobalt (Brewer and others, 1992). Selected samples reported by Foley (1987) contain up to 180 ppm nickel, 180 ppm copper, and 180 ppm zinc. Massive pyrrhotite-bearing samples contained 58.00 percent iron.

Comment (Reference): Primary Reference = Foley, 1987

Comment (Deposit): Model Name = Polymetallic replacement (?) (Cox and Singer, 1986; model 19a).

Comment (Deposit): Other Comments = See Post Lake Prospect (MG069).

Comment (Workings): Workings / Exploration = The Pyrrhotite occurrence was noted by the reporter during mapping conducted in 1981 (Bundtzen, Kline, and Clough, 1982). Grab samples of pyrrhotite-rich sulfide mineralization collected by Anaconda Minerals Company contained up to 0.44 percent nickel and 460 ppm cobalt (Brewer and others, 1992). Selected samples reported by Foley (1987) contain to 180 ppm nickel, 180 ppm copper, and 180 ppm zinc. Massive pyrrhotite-bearing samples contained up to 58.00 percent iron.

References

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.

Reference (Deposit): Brewer, N.H., Puchner, C.C., and Gemuts, I., 1992, Farewell district, southwest Alaska Range: North Pacific Mining Company prospectus report, 21 pages

Reference (Deposit): Foley, J.Y., 1987, Reconnaissance strategic and critical mineral investigations in the McGrath A-3 and B-2 quadrangles, southwest Alaska: U.S. Bureau of Mines Field Report, 26 pages.

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.

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