Scarp Occurrence, Alaska Peninsula District, Aleutians East Borough, Alaska, USA

This site is on land selected by the Aleut Corporation.
Location: This site is on a coastal bluff at an elevation of about 300 feet, approximately 1 mile north-northwest of Popof Head on the southern tip of Popof Island (Wilson and others, 1988, locality 44). The location is accurate to within 500 feet.
Geology: This occurrence is a 2,000- by 2,500- foot alteration zone in an area of slumped blocks of tuffs and flows. The rocks are part of the late Eocene to early Oligocene Popof volcanic rocks (Wilson and others, 1995). Mineralization consists of weakly auriferous quartz-marcasite-amethyst veins localized mostly along the margins of a slump block. The veins average 1.5 feet in width and can be traced for as much as 1,200 feet on strike. The veins generally are discontinuous, however, and do not seem to form a well -defined system (Peterson and others, 1982). The wall rock marginal to the veins has been replaced by silica and pyrite. Argillic alteration is widespread throughout the area. Some of the country rocks have been completely replaced by clay and some by pervasive chlorite and pyrite. The mineralization may be controlled by a north-northwest-trending fracture zone that can be traced for approximately 2 miles. Fifteen grab samples contained as much as 0.975 ppm gold, 13 ppm silver, 66 ppm copper, 45 ppm lead, 175 ppm zinc, 1,000 ppm or more arsenic, and 4.75 ppm mercury (Peterson and others, 1982). Two samples collected by Battle Mountain Exploration Company in 1986 contained 0.032 and 0.038 ounce of gold per ton and as much as 4.7 ppm mercury.
Workings: In 1982 UNC Teton Exploration Drilling Company mapped and sampled this occurrence. The samples contained as much as 0.975 ppm gold and 13 ppm silver.
Age: Eocene or younger.
Alteration: The rocks at this occurrence exhibit strong argillization and local silicification.

Commodities (Major) - Ag, Au; (Minor) - As, Hg
Development Status: None
Deposit Model: Epithermal gold veins

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.