Unnamed (north wall Grinnell Glacier)

The Unnamed (north wall Grinnell Glacier) is a copper 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: Unnamed (north wall Grinnell Glacier)

Commodity

Primary: Copper
Secondary: Zinc

Location

State: Alaska
District: Copper River

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: Massive sulfide, Besshi (Japanese deposits)

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Local alteration of copper minerals.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Sphalerite
Ore: Pyrrhotite
Ore: Pyrite
Ore: Malachite
Ore: Chalcopyrite
Ore: Arsenopyrite
Gangue: Sericite
Gangue: Quartz

Comments

Comment (Deposit): Model Name = Besshi massive sulfide (Cox and Singer, 1986; model 24b)

Comment (Geology): Age = Late Cretaceous based on the age of the host rocks.

Comment (Geology): Geologic Description = This occurrence consists of sulfide-bearing shear zones 2 to 10 feet wide in slate and greenstone of the Upper Cretaceous Valdez Group (Nelson and others, 1985). Ore minerals include arsenopyrite, chalcopyrite, malachite, pyrite, and pyrrhotite. Four chip samples collected and analyzed by the U.S. Bureau of Mines contained 255 ppm to 0.13% Cu; nine grab samples contained 13 ppm to 0.19% Cu (Jansons and others, 1984). This site is at the eastern end of a 65-mile-long belt of similar rocks that to the west host massive sulfide deposits (Nelson and others, 1984; 1985; Crowe and others, 1992). A massive-sulfide boulder found on the south side of Grinnel Glacier contained 30% pyrite, 3% chalcopyrite, 1% sphalerite in a quartz-sericite gangue (Kodosky and Teller, 1989). Assays of selected samples ranged from 1100 ppm to 1.8% Cu.

Comment (Deposit): Other Comments = Chugach Alaska Corporation, Anchorage, Alaska has control of these lands.

Comment (Reference): Primary Reference = Jansons and others, 1984

Comment (Exploration): Status = Inactive

Comment (Workings): Workings / Exploration = Site examined during U.S. Bureau of Mines and U.S.G.S. mineral resource assessment of the Chugach National Forest (Jansons and others, 1984; Nelson and others, 1984). Site also examined in 1988 by Kodosky and Teller (1989) for the Chugach Alaska Corporation. Their evaluation indicated some potential for copper mineralization. . Four chip samples collected and analyzed by the U.S. Bureau of Mines contained 255 ppm to 0.13% Cu; nine grab samples contained 13 ppm to 0.19% Cu (Jansons and others, 1984). A massive-sulfide boulder found on the south side of Grinnel Glacier contained 30% pyrite, 3% chalcopyrite, 1% sphalerite in a quartz-sericite gangue. Assays of selected samples ranged from 1100 ppm to 1.8% Cu.

References

Reference (Deposit): Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, Southcentral Alaska: U.S. Bureau of Mines Open-File Report 5-84, 218 p., 2 sheets, scale 1:250,000.

Reference (Deposit): Kodosky, Larry, and Teller, Steve, 1989, Economic mineral assessment of Chugach Alaska Corporation properties and selected land in the Copper, Bremner, and Tasnuna River area: unpublished report prepared for Chugach Alaska Corporation, Anchorage, Alaska, 116 p.

Reference (Deposit): Nelson, S.W., Miller, M.L., Barnes, D.F., Dumoulin, J.A., Goldfarb, R.J., Koski, R.A., Mull, C.G., Pickthorn, W.J., Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral resource potential of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-A, 24 p., 1 plate, scale 1:250,000.

Reference (Deposit): Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000.

Reference (Deposit): Crowe, D.E., Nelson, S.W., Brown, P.E., Shanks III, W.C., and Valley, J.W., 1992, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska: Economic Geology, v. 87, p. 1722-1746.

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