|Quadrangle map, 1:250,000-scale||DE|
|Quadrangle map, 1:63,360-scale||D-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||Roehm (1942) described the geology of this prospect in considerable detail but his location is ambiguous. It most likely is at an elevation of about 400 feet, close to the ridge between upper Coning Inlet and Seclusion Lake, near the center of the west boundary of section 22, T. 81 S., R. 85 E., but it may be a mile or more from there. The prospect was found with difficulty in 1952 by Glover (1954 [PE121-4]), but he does not provide an unambiguous location. In recent years, several other geologists (Maas and others, 1991; Hedderly-Smith, 1999) have unsuccessfully searched for the Foster prospect in heavily overgrown terrain that has been disturbed by logging.|
Geologic descriptionThe rocks in the vicinity of the likely location of the Foster prospect are pre-Ordovician dacitic metavolcanic rocks, marble, and argillite (Gehrels, 1991). Roehm (1942) describes the prospect as a quartz lens or vein about 170 feet long and 12 to 15 feet thick. The lens or vein strikes N42W and dips 75E; it is parallel to the schist, limestone, and argillite host rocks and contains numerous limestone fragments. The schist footwall is highly mineralized with small quartz lenses. The surface exposure of the vein appears barren due to surface oxidation, but a 10-foot-deep trench exposed abundant pyrite, chalcopyrite, sphalerite, and galena. Two 5-foot channel samples showed nil to 0.02 ounce of gold per ton, 0.10 to 0.30 ounce of silver per ton, 0.47 to 1.20 percent copper, up to 0.55 percent lead, and 0.18 to 1.22 percent zinc. The prospect was reexamined by Glover (1954 [PE 121-4]), but his oxidized surface samples contained little metal.
|Geologic map unit||(-132.709463745833, 54.8290546192676)|
|Mineral deposit model||Stratiform base metal deposit or volcanogenic massive-sulfide deposit.|
|Age of mineralization||Pre-Ordovician or younger.|
|Alteration of deposit||Much surface oxidation that has almost totally leached the sulfides.|
|Workings or exploration||A 10-foot-long trench apparently has been obliterated by forest growth and logging.|
|Indication of production||None|
Additional commentsThe subsurface rights to the land in the vicinity are held by the Sealaska Corporation.
Gehrels, G. E., 1991, Geologic map of Long Island and southern and central Dall Island, southeastern Alaska: U.S. Geological Survey Map MF-2146, 1 sheet, scale 1:63,360.
Glover, A. E., 1954, Investigations of H. F. Foster prospect, Coning Inlet, Long Island: Alaska Territorial Department of Mines, Property Examination 121-4, 3 p.
Hedderly-Smith, D.A., 1999, Inventory of metallic mineral prospects, showings and anomalies on Sealaska lands, 1988 through 1998: Sealaska Corporation, Juneau, Alaska, 217 p. (internal report held by Sealaska Corporation, Juneau, Alaska).
Maas, K.M., Bittenbender, P E., and Still, J.C., 1995, Mineral investigations in the Ketchikan mining district, southeastern Alaska: U.S. Bureau of Mines Open-File Report 11-95, 606 p.
Maas, K.M., Still, J.C., Clough, A.H., and Oliver, L.K., 1991, Mineral investigations in the Ketchikan mining district, Alaska, 1990: southern Prince of Wales Island and vicinity: U.S. Bureau of Mines Open-File Report 33-91, 139 p., 12 sheets, scale 1:63,360.
|Reporters||D.J. Grybeck (Applied Geology)|
|Last report date||9/1/2003|