Clark Bay

Occurrence, Inactive

Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Au; Mo; Zn
Ore minerals chalcopyrite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale SB
Quadrangle map, 1:63,360-scale D-6
Latitude 55.83
Longitude -159.9
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is located on the Alaska Peninsula, on Red Hill between Clark Bay and Grub Gulch (Christie, 1974, color anomaly 82; MacKevett and Holloway, 1977, locality 2; Wilson and others, 1988, locality 2). The map site is on the east shore of Clark Bay, due west of the center of sec. 5, T. 51 S., R. 69 W., of the Seward Meridian. The location is accurate to within 1 mile.

Geologic setting

Geologic description

This occurrence is marked by a color anomaly measuring approximately 8,000 by 4,300 feet (Christie 1974). The area contains Miocene basalt and andesite and Oligocene to Eocene sandstones and siltstones of the Stepovak Bay Formation (Wilson and others, 1995). Biotite from the volcanic rocks has been dated at 10 to 6 million years (Wilson and others, 1994).
Christie (1974) describes fine-grained porphyritic diorite at this location. The rock carries traces of chalcopyrite and as much as 1 percent pyrite. The volcanic rocks carry 1 to 12 percent pyrite. Soil and rock chip samples contained as much as 235 ppm copper, 0.46 ppm gold, 15 ppm molybdenum, 5.8 ppm silver, and 455 ppm zinc. Arbogast and others (1987) describes an intermediate intrusive rock containing abundant pyrite. Silt samples collected at this locality contained 100 ppm copper, 10 ppm molybdenum, and 1 ppm silver; pan concentrates contained 10 ppm molybdenum and 100 ppm tungsten (Frisken, 1992).
Geologic map unit (-159.902040719441, 55.8291931184806)
Mineral deposit model Porphyry Cu, Porphyry Cu-Mo, Porphyry Cu-Au (Cox and Singer, 1986; models 17, 21a, 20c)
Mineral deposit model number 17, 21a, 20c
Age of mineralization Tertiary.

Production and reserves

Workings or exploration This site was sampled by the Aleut-Quintana-Duval joint venture in 1974 (Christie, 1974). Additional sampling was carried out by the U.S. Geological Survey in the mid-1980s (Arbogast and others, 1987; Frisken, 1992).
Indication of production None

Additional comments

This site is on land selected by the Aleut Corporation.


MRDS Number 10308208


Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Reporters S.H. Pilcher
Last report date 10/18/2000