|Quadrangle map, 1:250,000-scale||SV|
|Quadrangle map, 1:63,360-scale||C-2|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Rossness and Larson mine is about 0.2 miles north of VAMB Mid on the north shore of the North Arm of Nuka Bay. The property consists of three short adits, numerous open cuts, and the ruins of the mill and camp. Two of the adits are near the beach at 30 and 50 feet above sea level; they are on each side of a small stream which drains into the cove. The third adit is at an elevation of 107 feet and about 250 feet northwest of the lower tunnels.|
The host rock of the prospect is graywacke and thin slate interbeds of the Cretaceous Valdez Group (Richter, 1970). The quartz veins of this prospect consist of white crystalline quartz with various amounts of sulfides. Arsenopyrite is the dominate sulfide with minor amounts of pyrite. Gold occurs as free gold and associated with arsenopyrite. The veins at this prospect are lens shaped and generally follow the bedding which strikes N30W and dips 67S (Pilgrim, 1933). They range from less than one inch to over four feet in width.
The southwest adit is 30 feet in length and follows a stockwork of parallel quartz veins. The veins range in width from 0.1 to 0.5 foot and strike N30W and dip 67S. A composite sample across four of these veins assayed 26 ppm gold (Richter, 1970). The northwest adit is caved and appears to have followed a single quartz-arsenopyrite vein that trends east-west and dips 80S. Richter (1970) sampled this vein and it contained 0.05 ppm gold.
The upper adit at 110 foot elevation trends east-west and dips 80S. There are no assay results from this adit.North of the two adits near the beach, there is a pyritized, light colored dike swarm which trends N20W. A sample of this dike swarm contained 0.028 ounces of gold per ton (Pilgrim,1933).
|Geologic map unit||(-150.59210020582, 59.5594164949227)|
|Mineral deposit model||Low-sulfide, Au-quartz vein (Cox and Singer, 1986; model 36a)|
|Mineral deposit model number||36a|
|Age of mineralization||Tertiary; Boden and others (1991) report other veins in the district are about 55 m.y. old.|
|Alteration of deposit||Borden and others (1991) report carbonization, sulfidization, sericitization, and silicification of the wall rock adjacent to the veins.|
|Workings or exploration||According to Pilgrim, (1933) the mine produced some gold during the 1931-33 period but it was inactive during Capps' 1936 visit (Capps, 1938, p. 32). Three adits totaling 170 feet in length and numerous surface cuts occur on the property. Composite samples by Richter (1970) of the southwest veins assayed 26 ppm gold. Samples by Pilgrim (1933) assayed between 0.08 and 0.064 ounces of gold and 0.40 ounces of silver per ton. A sample of the pyritic dike assayed 0.028 ounces of gold per ton (Pilgrim,1933).|
|Indication of production||Undetermined|
Additional commentsThis prospect is within the Kenai Fjords National Park; the park is closed to mineral entry.
Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p.
Borden, J.C., Goldfarb, R.J., Gent, C.A., Burruss, R.C., and Roushey, B.H., 1992 Geochemistry of lode-gold deposits, Nuka Bay district, southern Kenai Peninsula, in Bradley, D.C., and Dusel-Bacon, Cynthia, eds, Geologic studies in Alaska by the U.S. Geological Survey, 1991: U.S. Geological Survey Bulletin 2041, p. 13-21.
Capps, S.R., 1938, Lode mining in the Nuka Bay district, in Smith, P.S., and other, Mineral industry of Alaska in 1936: U.S. Geological Survey Bulletin 897-A, p. 25-32.
Cobb, E.H., 1972, Metallic mineral resources map of the Seldovia quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-397, 1 sheet, scale 1:250,000.
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than minerals fuels and construction materials) in the Seldovia quadrangle, Alaska: U.S. Geological Survey Open-file Report 80-87, 47 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Pilgrim, E.R., 1933, Nuka Bay district, in Stewart, B. D., Making mining investigations and mine inspection in Alaska, biennium ending March 31, 1933: Alaska Territorial Department of Mines Annual Report 1933B, p. 26-51.
|Reporters||Jeff A. Huber (Anchorage)|
|Last report date||2/17/1999|