Louis Bay

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Pb; Zn
Ore minerals chalcopyrite; pyrite; pyrrhotite; sphalerite
Gangue minerals chlorite; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-2
Latitude 60.4381
Longitude -147.6852
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located in the E1/2 section 15, T. 4 N., R. 10 E., of the Seward Meridian. The prospect consists of two adits; the lower adit is between elevations of 510 feet to 600 feet and the upper adit is between 830 to 900 feet elevation. This is location 199 of Cobb and Tysdal (1980) and location S-81 of Jansons and others (1984). This location is accurate to 1,000 feet.

Geologic setting

Geologic description

The country rock in the area of the prospect is greenstone and pillow basalt of the Orca Group of early Tertiary age (Cobb and Tysdal, 1980). The greenstone strikes N 20 to 45 E and dips nearly vertical. The workings consist of two adits that follow a north-trending, 4-foot-wide shear zone that dips nearly vertical. The lower adit is at about 640 feet elevation, and the upper adit is at about 1,000 feet elevation. Pyrrhotite and chalcopyrite are the dominant sulfides in the zone; pyrite and sphalerite are subordinate. Gangue minerals identified include quartz, chlorite, and epidote (Kurtak and Jeske, 1986).
Nine samples collected from all four adits by the U.S. Bureau of Mines contained between 25 ppm and 3.25 percent copper and from 0.3 to 14 ppm silver. The highest grade copper sample was a 10-foot-wide chip sample of a massive sulfide lens that is exposed in the 1,000 foot elevation adit. It contained 3.25 percent copper and 12.4 ppm silver (Kurtak and Jeske, 1986).
Geologic map unit (-147.687202810149, 60.4375004436696)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Tertiary or younger; the mineralization is in rocks of the Orca Group of Tertiary age.

Production and reserves

Workings or exploration
The workings consist of two adits that follow a north-trending, 4-foot-wide shear zone that dips nearly vertical. The lower adit is at about 640 feet elevation and the upper adit is at about 1000 feet elevation. The lower adit is collapsed; it was 165 feet long (Grant and Higgins, 1909; Kurtak and Jeske, 1986). The upper adit is about 75 feet long and has a 15-foot crosscut and a flooded winze of unknown depth (Kurtak and Jeske, 1986). There also two short adits west of the main shear zone; they follow another north-trending vertical shear zone. A 28-foot adit is at 1040 feet elevation, and there is a 6-foot adit at the 680 foot elevation. Improvements include a small steam sawmill, an electric plant, and a main camp near the beach (Moffit and Fellows, 1950).
Nine samples collected from all four adits by the U.S. Bureau of Mines contained between 25 ppm and 3.25 pervent copper and from 0.3 to 14 ppm silver. The highest grade copper sample was a 10 foot-wide chip sample of a massive sulfide lens that is exposed in the 1,000 foot elevation adit; it contained 3.25 percent copper and 12.4 ppm silver (Kurtak and Jeske, 1986).
Indication of production None

References

References

Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 12/15/2000