Beach Vein Prospect, Alaska Peninsula District, Aleutians East Borough, Alaska, USA

This prospect is located on land patented by, or interim-conveyed to, the Aleut Corporation.
Location: This prospect is located on the beach at the head of Acheredin Bay on Unga Island (Wilson and others, 1988, locality 34). The map site is due south of the center of sec. 32, T. 57 S., R. 75 W., of the Seward Meridian. The location is accurate to within 1,200 feet.
Geology: This prospect consists of a multiphase quartz vein system, locally called the Beach Vein, that averages approximately 10 feet in width and has been traced for 1,500 feet along strike. It occurs in argillized and silicified andesite of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995). Trenches have exposed 10 feet or more of mineralized quartz veins and as much as 18 feet of clay-rich, sheared andesite containing numerous thin quartz veins (Peterson and others, 1982). Drusy quartz breccias, as much as 400 feet long and 100 feet wide are present in the area. These contain abundant pyrite and minor chalcopyrite, galena, and sphalerite. Single-phase quartz veins as much as 6 inches wide occur along the margins of the Beach Vein. Ranges of metal values in the vein system are: gold, 0.005 to 4,937 ppm; silver, 1.8 to 14.6 ppm; copper, 45 to 5,400 ppm; lead, 18 to 11,300 ppm; zinc, 15 to 29,000 ppm; arsenic, 19 to 380 ppm; and mercury, 0.095 to 1,000 ppm (Peterson and others, 1982). Grab samples collected by Battle Mountain Exploration Company contained as much as 0.69 ppm gold; channel samples from trench 5 contained from 0.21 to 3.77 ppm gold (Pilcher, 1986).
Workings: In 1982 UNC Teton Exploration Drilling Company mapped the prospect, dug 421 feet of trenches, collected 105 channel and 25 grab samples, and conducted 2.8 line-miles of VLF-EM survey. The highest values from trench channel samples are 4,937 ppm gold, 14.6 ppm silver, 5,400 ppm copper, 11,300 ppm lead, 29,000 ppm zinc, 380 ppm arsenic, and 1,000 ppm mercury (Peterson and others, 1982).
Age: Eocene or younger.
Alteration: The alteration consists of argillization and minor silicification.

Commodities (Major) - Ag, Au; (Minor) - As, Cu, Hg, Pb, Zn
Development Status: None
Deposit Model: Epithermal gold veins, Polymetallic veins (Cox and Singer, 1986; model 22c)

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.) Pilcher, S.H., 1986, Unga project: Battle Mountain Exploration Company report, 33 p. (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.