Midway Occurrence, Alaska Peninsula District, Aleutians East Borough, Alaska, USA
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Location: This occurrence is located on Unga Island approximately 2 miles northeast of the head of Acheredin Bay and 4,000 feet north of Acheredin Lake (Wilson and others, 1988, locality 32). The map site is at an elevation of 1,100 feet, near the south end of the boundary between secs. 20 and 21, T. 57 S., R. 75 W., of the Seward Meridian. The location is accurate to within 2,500 feet.
Geology: This occurrence consists of several knobs of andesite breccia in an area 100 by 1,000 feet. The breccias contain pyrite, chalcedony, jasper, and zeolite. Samples of the breccia contained as much as 0.02 ppm gold, 15 ppm silver, 720 ppm zinc, 510 ppm arsenic, and 5 ppm mercury (Peterson and others, 1982). The andesite is part of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995).
Workings: UNC Teton Exploration Drilling Company sampled the occurrence in 1982. Samples contained as much as 0.02 ppm gold, 15 ppm silver, 720 ppm zinc, 510 ppm arsenic, and 5 ppm mercury.
Age: Eocene or younger.
Commodities (Major) - Ag, Au; (Minor) - Hg, Zn
Development Status: None
Deposit Model: Epithermal gold vein
Mineral List
3 entries listed. 1 valid mineral.
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References
Peterson, R.J., Lemmers, J., Handverger, P., Gallagher, J., Pilcher, R., East, J., Macleod, T., Bartels. E., 1982, Geology and precious metals potential Unga, Popof, and Korovin Islands, Shumagin Group, Aleutian Chain, Alaska: UNC Teton Exploration Drilling Company report, 127 p., 5 map sheets, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.) Wilson, F.H., Detterman, R.L., Miller, J. W., and Case, J.E., 1995, Geologic map of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigation Series Map I-2272, 1 sheet, scale 1:250,000. Wilson, F.H., White, W.H., and DuBois, G.D., 1988, Brief descriptions of mines, prospects, and mineral occurrences in the Port Moller and Stepovak Bay quadrangles, Alaska Peninsula: U.S. Geological Survey Open-File Report 88-666, 128 p., 1 plate, scale 1:250,000.