Mt. Baker

Prospect, Undetermined

Alternative names

Baker Peak

Commodities and mineralogy

Main commodities Ag; Au; Cu
Other commodities Pb
Ore minerals chalcopyrite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale D-7
Latitude 57.8171
Longitude -136.2426
Nearby scientific data Find additional scientific data near this location
Location and accuracy 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.

Geologic setting

Geologic description

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.
Geologic map unit (-136.244430328909, 57.8167224725368)
Mineral deposit model Basaltic copper (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization The primary copper mineralization probably is Triassic, the probable age of the greenstone host rock.
Alteration of deposit Intense unspecified alteration of greenstone and aplite host rocks.

Production and reserves

Workings or exploration 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).
Indication of production None

Additional comments

The prospect is in West Chichagof-Yakobi Wilderness.

References

MRDS Number A013258

References

Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p.
Moerlein, G.A., 1971, Geology, geophysics, and geochemistry, Mt. Baker copper prospect, Alaska: Unpublished report, 6 p., 4 maps. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska.)
Thorne, R.L., 1960, Chichagof-Alaskan Mining Corporation, Lucky Devil claims, Chichagof Island, Alaska: Unpublished U. S. Bureau of Mines Examination Report, 9 p. (Report held by the Mineral Information Center, Bureau of Land Management, Juneau, Alaska.)
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
Reporters H.C. Berg (U.S. Geological Survey)
Last report date 10/16/2004