Hogan

Prospect, Inactive

Alternative names

Hemple and Egan
Hemple Bay

Commodities and mineralogy

Main commodities Cu
Ore minerals bornite; chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale A-3
Latitude 60.2066
Longitude -147.7752
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located at an elevation of about 900 feet near the top of a ridge that separates Thumb Bay from Hogan Bay. It is in the E1/2 section 6, T. 1 N., R. 10 E., of the Seward Meridian. This is location 118 of Cobb and Richter (1972), location 147 of MacKevett and Holloway (1977), location 252 of Cobb and Tysdal (1980), and location S-27 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The country rock at the prospect is graywacke of the Orca Group of early Tertiary age. It generally strikes northeast and dips 42 to 70 W (Cobb and Tysdal, 1980). In the lower adit, diorite forms an irregular contact with the graywacke. There is no mineralization associated with the diorite (Kurtak and Jeske, 1986). Several shear zones, as much as 5 feet wide, trend northeast, but most dip more steeply than the graywacke. The shear zones, which are confined to the graywacke, contain 1- to 5-foot-wide sulfide-bearing zones consisting of as much as 5 percent chalcopyrite stringers, as much as 2 percent pyrite with minor amounts of bornite, and some quartz veinlets and lenses as much as 6 inches wide (Kurtak and Jeske, 1986). Four chip samples were collected by the U.S. Bureau of Mines (Kurtak and Jeske, 1986); three samples contained 0.78 percent, 0.89 percent, and 0.99 percent copper, respectively, and from 2 to 4 ppm silver. One sample contained 2.2 percent copper and 8.6 ppm silver.
Geologic map unit (-147.77724467933, 60.2060249952332)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Tertiary or younger; the occurrence is in rocks of the Orca Group of Tertiary age.

Production and reserves

Workings or exploration Workings on the prospect consist of three adits that are 45, 65, and 140 feet long, respectively. Four chip samples were collected by the U.S. Bureau of Mines (Kurtak and Jeske, 1986); three samples contained 0.78 percent, 0.89 percent, and 0.99 percent copper, respectively, and 2 to 4 ppm silver. One sample contained 2.2 percent copper and 8.6 ppm silver.
Indication of production None

References

MRDS Number A010406

References

Shepard, J.G., 1925, The Hemple Bay prospect, Hogan Bay, Knight Island, Alaska: USGS unpublished report, 2 p.
Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 3/9/2001