Hanson and Bolshan (Elbow Passage)

Prospect, Undetermined

Commodities and mineralogy

Main commodities Au
Ore minerals gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SI
Quadrangle map, 1:63,360-scale C-7
Latitude 57.6138
Longitude -136.0836
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Hanson and Bolshan prospect is at sea level on the east side of Elbow Passage, about 0.5 mile south of the entrance to Lake Anna. The prospect is at the midpoint of the south boundary of sec. 15, T. 49 S., R. 58 E. It is location P-68 of Bittenbender and others (1999), location 39 of Cobb (1972, 1978), and MAS nos. 0021140031 and 0021140311 (U.S. Bureau of Land Management, 2002). The location is accurate within 0.2 mile.

Geologic setting

Geologic description

Johnson and Karl (1985) map the rocks in the area of this prospect as Cretaceous graywacke and argillite interbedded with sparse, lenticular beds of basalt. The rocks are cut by numerous high-angle, mainly northwest-striking faults.
Reed and Coats (1941) report a 29-foot shaft and several pits at this prospect. The country rock is distinctly jointed, slaty graywacke that strikes about N57W and dips 70SW; the principal joint set strikes N40E and dips about 80NW. The shaft follows a fault that strikes N48W and dips 84SW. Quartz veinlets up to an inch thick fill joints in the hanging wall and are truncated by the fault. The bottom few feet of the shaft exposed up to a foot of pyrite-bearing ribbon quartz. The surface pits exposed other faults that may correlate with the one in the shaft. A few hundred feet from the shaft a 6- to 12-inch quartz vein in a N40E 70NW joint reportedly contained significant, but unspecified, gold values.
Bittenbender and others (1999), citing Smith (1926), report that samples from dumps at this prospect contained up to 0.915 ounce of gold per ton. There is no record of production.
Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler, 1995; Goldfarb, 1997; Goldfarb and others, 1997). ARDF record SI087 provides an overview of the geology of auriferous quartz veins in the Chichagof Mining District.
Geologic map unit (-136.085419794579, 57.6134301422805)
Mineral deposit model Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).

Production and reserves

Workings or exploration Reed and Coats (1941) report a 29-foot shaft and several pits at this prospect.
Indication of production Undetermined
Production notes There is no record of production.

Additional comments

The prospect is in West Chichagof-Yakobi Wilderness.

References

MRDS Number A013283

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.
Goldfarb, R J., 1997, Metallogenic evolution of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., and Taylor, C., 1995, Link between ridge subduction and gold mineralization in southern Alaska: Geology, v. 23, no. 11, p. 995-998.
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