Unnamed (south of Kwain Bay)

Occurrences, Undetermined

Commodities and mineralogy

Main commodities Au; Cu
Other commodities Pb; Zn
Ore minerals chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale A-5
Latitude 55.075
Longitude -131.361
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site represents seven occurrences: six are at sea level, 0.5-1.3 miles south of the mouth of Kwain Bay; and one is at an elevation of about 500 feet at the eastern foot of Tamgas Mountain, about 1.4 miles east-northeast of the mountain peak. The occurrences are in sections 26 and 35, T. 78 S., R. 93 E., of the Copper River Meridian. The map site is at the approximate center of the estimated half-square-mile area that contains these occurrences. The site corresponds to loc. 37a-g in Karl (1992). The location is accurate within about 0.2 mile.

Geologic setting

Geologic description

The country rocks in the area of this site include undivided, metamorphosed Silurian and Ordovician volcanic, sedimentary, and intrusive rocks; Silurian trondhjemite that intrudes the Silurian and Ordovician assemblage; and recrystallized, Upper Triassic carbonate and clastic rocks, rhyolite, and basalt that unconformably overlie the Paleozoic rocks (Berg, 1972 [I 684]; Berg and others, 1988). The rocks were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.
The occurrences consist of pyrite- and chalcopyrite-bearing quartz fissure veins in locally sheared, felsic to mafic metavolcanic and volcaniclastic rocks (Karl, 1992, loc. 37a-g). The presence of small amounts of galena and sphalerite is inferred from sample assays. The sulfides also occur as disseminations and seams in the volcaniclastic rocks.
A sample of pyrite[?] contained 100 ppm Pb, 300 ppm Zn, 300 ppm Cr, 200 ppm Ni, and 1000 ppm As; samples of various, sulfide-bearing country rocks contained up to 0.08 ppm Au, 2 ppm Ag, 1500 ppm Cu, 10 ppm Mo, 100 ppm Co, and 300 ppm Ni; samples of quartz veins contained up to 0.1 ppm Au, 2 ppm Ag, and 500 ppm Cu; and a soil survey conducted in the 1970s by private interests reportedly showed detectable gold (Karl, 1992, loc. 37a-g).
Geologic map unit (-131.362680192249, 55.0746614884556)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Fissure veins probably are Late Cretaceous or younger.

Production and reserves

Workings or exploration A sample of pyrite[?] contained 100 ppm Pb, 300 ppm Zn, 300 ppm Cr, 200 ppm Ni, and 1000 ppm As; samples of various, sulfide-bearing country rocks contained up to 0.08 ppm Au, 2 ppm Ag, 1500 ppm Cu, 10 ppm Mo, 100 ppm Co, and 300 ppm Ni; samples of quartz veins contained up to 0.1 ppm Au, 2 ppm Ag, and 500 ppm Cu; and a soil survey conducted in the 1970s by private interests reportedly showed detectable gold (Karl, 1992, loc. 37a-g).
Indication of production None

References