|Quadrangle map, 1:250,000-scale||SB|
|Quadrangle map, 1:63,360-scale||D-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The map site of this approximately located occurrence is at an elevation of about 3,200 feet, at the midpoint of the boundary between secs 10 and 15, T. 49 S., R. 69 W., of the Seward Meridian. (Wilson and others, 1988, locality 10). The location is probably accurate to within 4 miles.|
This occurrence is a sulfur deposit in an area of Quaternary volcanic rocks (Wilson and others, 1995). The sulfur-bearing rock is estimated to be approximately 100 feet thick and to extend approximately 2,500 feet along in the wall of a cirque (Maddren, 1919). Possible extensions are snow-covered. Steaming fumaroles are visible at the west end of the deposit. The outcrop faces south and is visible from Ramsey Bay.The deposit is not accessible and the following description is based on sulfur-bearing boulders as much as 40 feet in diameter, which occur in the moraine below the deposit. The sulfur occurs in the interstices of volcanic breccia and in vesicles in the breccia fragments. Some of the sulfur forms veins 1/8 to 1/4 inches thick; bulk samples of these veins are estimated to contain as much as 20 percent sulfur (Maddren, 1919). Most of the sulfur is finely disseminated in rock that is estimated to contain 5 to 10 percent sulfur. Fine-grained disseminated pyrite, accompanied by opal, occurs locally. One sample contained 50 percent pyrite and 50 percent opal (Eakins, 1970).
|Geologic map unit||(-159.90205230029, 55.8991938828189)|
|Mineral deposit model||Fumarolic sulfur|
|Age of mineralization||Quaternary.|
|Alteration of deposit||Argillic?|
|Indication of production||None|
Additional commentsThis location is inacessible, and information is based on float samples. It is on land selected by the Aleut Corporation.
Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 p.
Eakins, G.R., 1970, Mineralization near Stepovak Bay, Alaska Peninsula, Alaska: Alaska Division of Mines and Geology Special Report 4, 12 p.
Maddren, A.G., 1919, Sulfur on Unalaska and Akun Islands and near Stepovak Bay: U.S. Geological Survey Bulletin 692-E, p. 283-298.
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.
|Last report date||11/4/2000|