Mt. Baker; Baker Peak Prospect, Chichagof Mining District (Chicagof Mining District), Sitka, Alaska, USAi

Regional Level Types
Mt. Baker; Baker Peak Prospect	Prospect
Chichagof Mining District (Chicagof Mining District)	Mining District
Sitka	City Borough
Alaska	State
USA	Country

The prospect is in West Chichagof-Yakobi Wilderness.
Location: This prospect is at an elevation of about 1,800 feet on the north flank of Mount Baker. The prospect is 0.4 mile south-southwest of the center of sec. 6, T. 47 S., R. 57 E. It is location P-44 of Bittenbender and others (1999) and MAS no. 0021140009 (U.S. Bureau of Land Management, 2002). The location is accurate.
Geology: Johnson and Karl (1985) map the rocks in the area of this prospect as Triassic(?) greenstone. The greenstone is cut by high-angle faults that mainly strike northwest. The most prominent is the regional-scale Border Ranges Fault, whose trace is about a mile southwest of the prospect. Cobb (1972, 1978), citing Overbeck (1919), describes the host rocks as greenstone cut by aplite dikes. Both are mineralized and intensely altered. The mineralization consists of abundant pyrite and locally massive chalcopyrite. Assays of the mineralized rock showed gold, silver, and lead, but no lead mineral is identified. The deposit was discovered in 1910 and explored by about 300 feet of tunnels and crosscuts, a shallow shaft, and open cuts. Bittenbender and others (1999) report that the largest concentration of copper is in a 400-foot-long, northwest-striking, vertical fault(?) zone. Samples at a shallow shaft at the northwest end of the zone contained up to 7.5 percent copper and some silver, across 2 feet. Samples from a trench at the southeast end of the zone contained 2.0 percent copper across 13 feet. Underground and surface workings expose mineralized rock between 1,300 and 2,000 feet in elevation. The U.S. Bureau of Mines sampled the property at the surface and underground in 1960 (Thorne, 1960); it was explored in 1962 by magnetic and self-potential surveys (Bush and Kenly, 1962); and soil sampled in 1971 (Moerlein, 1971). There has been no production.
Workings: The deposit was discovered in 1910 and explored by about 300 feet of tunnels and crosscuts, a shallow shaft, and open cuts. Underground and surface workings expose mineralized rock between elevations of 1,300 and 2,000 feet. The U.S. Bureau of Mines sampled the property at the surface and underground in 1960 (Thorne, 1960); it was explored in 1962 by magnetic and self-potential surveys (Bush and Kenly, 1962); and soil sampled in 1971 (Moerlein, 1971).
Age: The primary copper mineralization probably is Triassic, the probable age of the greenstone host rock.
Alteration: Intense unspecified alteration of greenstone and aplite host rocks.

Commodities (Major) - Ag, Au, Cu; (Minor) - Pb
Development Status: None
Deposit Model: Basaltic copper (Cox and Singer, 1986; model 23).

Other Databases

Link to USGS - Alaska:	SI036

Other Regions, Features and Areas containing this locality

References