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Unnamed (east of Blunt Mountain)

Occurrences, Undetermined

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Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale A-5
Latitude 55.142
Longitude -131.363
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site represents three occurrences east of Blunt Mountain. The occurrences are in section 2, T. 78 S., R. 93 E., of the Copper River Meridian and section 35, T. 77 S., R. 93 E., of the Copper River Meridian. They range in elevation from about 300 feet to sealevel, and are about 1.3-1.5 miles from the highest point on Blunt Mountain. The coordinates are for the approximate center of the half-square-mile area that contains the occurrences. The site corresponds to loc. 3 in Berg (1972 [I 684]), loc. 143 in Elliott and others (1978), and loc. 29a-c in Karl (1992). The location is accurate within about 0.1 mile.

Geologic setting

Geologic description

The country rocks in the area of this site are recrystallized, Upper Triassic rhyolite, felsic tuff, and limestone (Berg, 1972). The rocks are folded and complexly faulted, and were regionally metamorphosed to greenschist-grade phyllite and semischist in Late Cretaceous time.
The occurrences consist of sparsely mineralized, auriferous, sulfide-bearing quartz fissure veins in rhyolite that locally is sheared, sericitized, and impregnated with finely disseminated iron oxide. The veins are up to about 3 feet thick and contain sparse clots of pyrite and other sulfide minerals that, judging from sample assays, include galena, chalcopyrite, and sphalerite. Samples of variously mineralized quartz veins and country rocks contained up to 0.43 oz. Au/ton; 0.91 oz. Ag/ton, 2% Pb, 16.75% Zn, and 1.25% Cu (Berg, 1972, loc. 3; Karl, 1992, loc. 29).
Geologic map unit (-131.364682299396, 55.1416595288024)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Probably Late Cretaceous or younger.
Alteration of deposit Local sericitization and iron-oxide alteration.

Production and reserves

Workings or exploration Samples of variously mineralized quartz veins and country rocks contained up to 0.43 oz. Au/ton; 0.91 oz. Ag/ton, 2% Pb, 16.75% Zn, and 1.25% Cu (Berg, 1972, loc. 3; Karl, 1992, loc. 29).
Indication of production None

References

MRDS Number A012384

References

Berg, H.C., 1972, Geologic map of Annette Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-684, 8 p., 1 sheet, scale 1:63,360.
Elliott, R.L., Berg, H.C., and Karl, S.M.,1978, Map and table describing metalliferous and selected non-metalliferous mineral deposits in the Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-73B, 17 p., 1 sheet, scale 1:250,000.
Reporters H.C. Berg, USGS
Last report date 7/6/1999