Unnamed (between Cascade and Derickson Bays)

Occurrences, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Cu
Ore minerals arsenopyrite; chalcopyrite; gold; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-3
Latitude 60.8943
Longitude -147.8103
Nearby scientific data Find additional scientific data near this location
Location and accuracy Several occurrences are located on the west and northeast flanks of hill 2477, about midway between Casade Bay and Derickson Bay. The map site is in the SW1/4 section 2, T. 9 N., R. 9 E., of the Seward Meridian. This is location S-124 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The occurrences consist of several quartz-sulfide veins in the Contact Fault zone, a major regional structure that separates the Valdez Group of Cretaceous age from the Orca Group of Tertiary age (Jansons and others, 1984). The veins generally are folded and boudinaged and form an en echelon array within the Contact Fault. The general strike and dip of the veins are N35E and 70 to 80 NW. Hoekzema and Sherman (1983) did not specify whether the host rock is Valdez Group or Orca Group strata.
The veins contain pyrite, arsenopyrite, and chalcopyrite that occur as disseminated grains and as massive lenses and pods in the core and along the margins of the veins. Samples collected by the U.S. Bureau of Mines in 1981 contained as much as 0.13 ppm gold and 1.3 ppm silver, along with as much as 2,600 ppm arsenic (Hoekzema and Sherman, 1983).
Geologic map unit (-147.81237110386, 60.8937726483873)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Oligocene or younger; the Contact Fault cuts Oligocene intrusive rocks northeast of this occurrence.

Production and reserves

Workings or exploration The occurrences were discovered and sampled by the U.S. Bureau of Mines in 1981. Their samples contained as much as 0.13 ppm gold and 1.3 ppm silver, along with as much 2,600 ppm arsenic (Hoekzema and Sherman, 1983).
Indication of production None

References

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 1/1/2000