Unnamed Occurrences (ARDF - KC146), Blunt Mountain, Annette Island, Ketchikan District, Prince of Wales-Outer Ketchikan Borough, Alaska, USA
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Geology: 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).
Workings: 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).
Age: Probably Late Cretaceous or younger.
Alteration: Local sericitization and iron-oxide alteration.
Commodities (Major) - Ag, Au, Cu, Pb, Zn
Development Status: None
Deposit Model: Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral List
5 entries listed. 5 valid minerals.
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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. Karl, S.M., 1992, Map and table of mineral deposits on Annette Island, Alaska: U.S. Geological Survey Open-File Report 92-690, 57 p., 1 map, scale 1:63,360.