|Quadrangle map, 1:250,000-scale||CR|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Alpha prospect is about 0.2 mile north of the center of Lake Williams and about 0.4 mile southwest of the center of section 32, T. 77 S., R. 89 E.|
Geologic descriptionAs described by Brooks (1902) and Wright and Wright (1908), the Alpha prospect is a quartz vein up to 5 feet wide that can be traced for nearly 2,000 feet. The vein is in white crystalline marble and strikes about north and dips 45W. It contains sparse pyrite and chalcopyrite; early samples contained about $4 to $25 per ton in gold (at $20.67 per ounce). Maas and others (1991, 1995) found a caved shaft, a short adit, and several trenches. Their samples contained up to 62 parts per billion gold and 1.8 percent copper. The rocks in the Dolomi area are part of the Wales Group of Late Proterozoic and Cambrian age (Herreid, 1967). They are folded into a large dome centered over the eastern third of Paul Lake, and consist of several marble layers 200 to 1300 feet thick, interbedded with calcareous chlorite schist and marble.
|Geologic map unit||(-132.044301883515, 55.1466642857933)|
|Mineral deposit model||Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Vein is younger than the Late Proterozoic or Cambrian host rocks.|
|Workings or exploration||The workings include a shallow, caved shaft, a short adit, and several trenches.|
|Indication of production||None|
|Production notes||Apparently none.|
Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.
Cobb, E. H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-869, 262 p.
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||5/1/2004|