Copper King

Prospect, Inactive

Alternative names

Black Prince
Grubstakers Incorporated

Commodities and mineralogy

Main commodities Cu; Fe
Other commodities Ag; Au
Ore minerals azurite; chalcopyrite; magnetite; malachite; marcasite; pyrite; pyrrhotite
Gangue minerals epidote; garnet; quartz

Geographic location

Quadrangle map, 1:250,000-scale IL
Quadrangle map, 1:63,360-scale C-2
Latitude 59.6781
Longitude -153.6634
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Copper King prospect is at an elevation of about 1,250 feet, about 1.25 miles west-southwest of Williamsport on Iliamna Bay. The prospect is near the west end of the boundary between secs. 2 and 11, T. 6 S., R. 26 W., Seward Meridian. The location is accurate for the center of the prospect area, which probably extends from about 1,000 feet to 1,500 feet in elevation. It is location 7 of Detterman and Cobb (1972).

Geologic setting

Geologic description

This prospect consists mainly of epidote-garnet-quartz skarn containing magnetite, chalcopyrite, pyrite, pyrrhotite, marcasite, and the oxidized copper minerals azurite and malachite. The deposit is in carbonate masses which occur as roof pendants and isolated lenses in Jurassic quartz diorite (Martin and Katz, 1910, 1912; Jasper, 1955; Detterman and Reed, 1980). The host rocks are part of the Permian(?) to Jurassic Kokhonak Complex composed of schist, gneiss, phyllite, and marble (Detterman and Reed, 1980).
The maximum width of mineralization reported by Jasper (1955) is 70 feet; most zones are much thinner. According to Jasper, magnetite and chalcopyrite, accompanied by quartz and subordinate pyrite, replace limestone; garnet-magnetite skarn is developed locally; and some granitic(?) rock has been epidotized. The chalcopyrite is locally oxidized to malachite and azurite. Marcasite, reported by Jasper (1955), possibly formed by late hypogene replacement of pyrrhotite and pyrite.
Samples of magnetite- and pyrite-rich rock collected by Jasper (1955, p. 5) assayed up to a detectable trace of gold, 0.96 ounce of silver per ton, and 0.89 percent copper. The prospect owners reported higher copper values in selected samples of material (Jasper, 1955), but in deposits too small to mine (Berg and Cobb, 1967).
Geologic map unit (-153.665616202335, 59.6774610888588)
Mineral deposit model Cu skarn?, Fe skarn? (Cox and Singer, 1986; models 18b, 18d).
Mineral deposit model number 18b?, 18d?
Age of mineralization Probably Jurassic.
Alteration of deposit Marble roof pendants and isolated lenses in quartz diorite are silicified and pyritized. Some masses have been altered to garnet and magnetite rock. Epidote skarn locally formed in marble and in the intrusion(?). Oxidation of copper.

Production and reserves

Workings or exploration The prospect was located by Charles Keys in 1905. Martin and Katz (1910) reported two prospect pits near the contact of hornblende quartz diorite and greenstone. By 1912, Martin and Katz (1912) reported nine claims on the steep slope. The prospect was apparently inactive and abandoned until about 1955, when Grubstakers, Inc., filed four claims on the property. Jasper (1955) examined the property and concluded that it did not warrant any further work. His channel samples yielded up to trace amounts of gold, 0.96 ounce of silver per ton, and 0.89 percent copper.
Indication of production None


MRDS Number A013037


Reporters C.C. Hawley, Hawley Resource Group, Anchorage, Alaska
Last report date 6/8/2003