Threeman Mining Co.

Prospect in Alaska, United States with commodities Copper, Zinc, Silver

Geologic information

Identification information

Deposit ID 10307355
Record type Site
Current site name Threeman Mining Co.

Geographic coordinates

Geographic coordinates: -146.57254, 60.87359 (WGS84)
Relative position This prospect is at an elevation of about 1600 ft., approximately 0.75 mi. northeast of Copper Mountain. It is in S1/2 sec. 36, T. 11 S., R. 8 W., of the Copper River Meridian. The location is accurate to within 1000 ft. This site is shown as C-82 in Jansons and others (1984).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Zinc Primary
Silver Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrrhotite Ore

Mineral occurrence model information

Model code 90
USGS model code 24a
Deposit model name Massive sulfide, Cyprus
Mark3 model number 11

Nearby scientific data

(1) -146.57254, 60.87359

Comments on the geologic information

  • Geologic Description = The country rocks at this prospect are mafic volcanic rocks and sedimentary rocks of the Tertiary Orca Group (Nelson and others, 1985). The deposit consists of up to foot-thick lenses of chalcopyrite and pyrrhotite.in two-foot- to 15-foot-wide shear zones. Three chip samples contained 200 ppm to 1% Cu, 145 ppm to 0.89% Zn, and <0.2 to 6 ppm Ag; a grab sample from the dump contained 4.9% Cu, 0.49% Zn, and 50 ppm Ag (Jansons and others, 1984).
  • Age = Probably Tertiary based on the age of the host rocks.

Economic information

Economic information about the deposit and operations

Development status Prospect

Comments on exploration

  • Status = Inactive

Mining district

District name Copper River

Comments on the workings information

  • Workings / Exploration = One 41-foot-long adit. Three chip samples contained 200 ppm to 1% Cu, 145 ppm to 0.89% Zn, and <0.2 to 6 ppm Ag; a grab sample from the dump contained 4.9% Cu, 0.49% Zn, and 50 ppm Ag (Jansons and others, 1984).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF CV012

Bibliographic references

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

Comments on the references

  • Primary Reference = Jansons and others, 1984

General comments

Subject category Comment text
Deposit Model Name = Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
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.

Reporter information

Type Date Name Affiliation Comment
Reporter 10-JUN-00 S.W. Nelson U.S. Geological Survey