Copper Coin

Mine, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Zn
Ore minerals chalcopyrite; covellite; cubanite; pyrrhotite; sphalerite
Gangue minerals epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-3
Latitude 60.3123
Longitude -147.7749
Nearby scientific data Find additional scientific data near this location
Location and accuracy The mine is located on the southeast shore of Drier Bay about half a mile southwest of Barnes Cove at an elevation of about 500 feet. This is in the NE1/4 section 31, T. 3 N., R. 10 E., of the Seward Meridian. This is location 230 of Cobb and Tysdal (1980) and location S-50 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

According to Kurtak and Jeske (1986), the mine workings expose an iron-stained shear zone that trends N15W and dips 40 to 80 NW. It averages 4 feet in width. The host rock is sheared greenstone that exhibits various degrees of chloritization (Kurtak and Jeske, 1986). Nelson and others (1985) mapped this area as Orca Group of early Tertiary age. Massive sulfide lenses composed mainly of pyrrhotite and chalcopyrite as much as 6 inches thick occur throughout the greenstone. They can be traced for about 240 feet along strike (Kurtak and Jeske, 1986). Other minor sulfide minerals include cubanite, covellite, and sphalerite. A 60-foot-long adit at 518 feet elevation was driven S10E along the shear zone. Massive sulfide mineralization consisting mostly of pyrrhotite with some chalcopyrite occurs along both the hanging wall and footwall. Samples from this zone contained from 280 ppm to 13 percent copper along with trace amounts of silver and gold. Samples from the open cut at 453 feet elevation contained 0.15 percent to 1.6 percent copper (Kurtak and Jeske, 1986).
Geologic map unit (-147.776959010103, 60.3117407408992)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Tertiary or younger; the occurrence is in rocks of the Orca Group of Tertiary age.
Alteration of deposit Kurtak and Jeske (1986) reported the greenstone shows various degrees of chloritization.

Production and reserves

Workings or exploration Workings at the mine consist of two adits and an open cut. A 60-foot adit at 518 feet elevation strikes S10E. A 6-foot adit at 435 feet elevation strikes N60W. The open cut is at 560 feet elevation. The U.S. Bureau of Mines visited the prospect in the early 1980s and found both adits but only one open cut (Kurtak and Jeske, 1986). Improvements consisted of a small wharf, two cabins on the beach, a wire tram, and a trail leading to the workings. Eight samples from the adits contained from 280 ppm to 13 percent copper along with trace amounts of silver and gold (Kurtak and Jeske, 1986).
Indication of production Yes; small
Reserve estimates Chugach Alaska Corporation estimated a reserve of 5,900 tons of ore containing 2.4 percent copper, 0.3 ounce of silver per ton, and 0.03 ounce of gold per ton (Hoyt and Rogers, 2000).
Production notes In July 1908, the Russell Ball Copper Company shipped a small amount of copper ore (Johnson, 1918 [B 662-C, p. 184, 216-217]).

References

MRDS Number A010376

References

Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 11/9/2001