Threeman (Standard Copper)

The Threeman (Standard Copper) is a copper and zinc 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: Threeman (Standard Copper)

Commodity

Primary: Copper
Primary: Zinc
Secondary: Silver
Secondary: Cobalt
Secondary: Gold

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: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Massive sulfide, Cyprus

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Sphalerite
Ore: Pyrrhotite
Ore: Pyrite
Ore: Galena
Ore: Cubanite
Ore: Chalcopyrite

Comments

Comment (Geology): Age = Probably Tertiary baased on the age of the host rocks.

Comment (Production): Production Notes = 1,159,660 lbs. Cu, 101 oz. Au, 5,308 oz. Ag from 6,196.5 tons ore (Mihelich and Wells, 1957).

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

Comment (Deposit): Other Comments = Nelson and others (1985) interpret the country rocks as accreted ocean crust. Crowe and others (1992; 1993) and Sainsbury (1993) discuss the genesis of the volcanogenic massive sulfide deposits in this area.. Chugach Alaska Corporation, Anchorage, Alaska has control of these lands.

Comment (Geology): Geologic Description = The deposit at this mine is in mafic volcanic and sedimentary rocks of the Tertiary Orca Group (Nelson and others, 1985). It consists of two sulfide lenses up to about 6 ft wide and over 300 ft. long in pillow basalt and sedimentary rocks (Mihelich and Wells, 1957). Sulfide minerals include chalcopyrite, cubanite, galena, pyrite, pyrrhotite, and sphalerite. Chip and grab samples contained 53 ppm to 5.25% Cu, 40 ppm to 2.85% Zn, <0.02 ppm to 0.10 ppm Au, <1 ppm to 22 ppm Ag, and 5 to 700 ppm Co (Jansons and others, 1984). Sixteen chip samples taken in 1955 contained 0.3 % to 8.6% Cu, 0.05% to 0.64% Zn, trace to 0.07 oz.Au/ton and trace to 0.78 oz. Ag/ton (Mihelich and Wells, 1957).

Comment (Exploration): Status = Inactive

Comment (Workings): Workings / Exploration = There are several thousand feet of workings on three levels. Three adits were caved when visited by this reporter in 1974 and 1986 (also see Sainsbury, 1993). Chip and grab samples contained 53 ppm to 5.25% Cu, 40 ppm to 2.85% Zn, <0.02 ppm to 0.10 ppm Au, <1 ppm to 22 ppm Ag, and 5 to 700 ppm Co (Jansons and others, 1984). Sixteen chip samples taken in 1955 contained 0.3 % to 8.6% Cu, 0.05% to 0.64% Zn, trace to 0.07 oz.Au/ton and trace to 0.78 oz. Ag/ton (Mihelich and Wells, 1957).

Comment (Reserve-Resource): Reserves = Inferred reserves of 1,902,000 tons @ 1.05% Cu (Sainsbury, 1953).

Comment (Reference): Primary Reference = Mihelich and Wells, 1957

References

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): Sainsbury, C.L., 1993, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska, A discussion: Economic Geology, v. 88, p. 1284-1285.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Cordova quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-392, 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., 1993, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound, south-central Alaska-A reply: Economic Geology, v. 88, p. 1285-1288.

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.

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): Mihelich, M., and Wells, R.R., 1957, Copper mines and prospects adjacent to Landlocked Bay, Prince William Sound, Alaska: U.S. Bureau of Mines Report of Investigations RI 5320, 21 p.

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