Threeman Mining Co. Prospect, Copper River Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Threeman Mining Co. Prospect	Prospect
Copper River Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

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.
Location: 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).
Geology: 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).
Workings: 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).
Age: Probably Tertiary based on the age of the host rocks.

Commodities (Major) - Cu, Zn; (Minor) - Ag
Development Status: None
Deposit Model: Cyprus massive sulfide (Cox and Singer, 1986; model 24a)

Other Databases

Link to USGS - Alaska:	CV012

Other Regions, Features and Areas containing this locality

References