|Quadrangle map, 1:250,000-scale||SI|
|Quadrangle map, 1:63,360-scale||C-7|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Bauer (Radio) prospect is a few feet above sea level, about 0.4 mile west of Fox Point at the northeast tip of Herbert Graves Island. The prospect is 0.3 mile north-northeast of the southwest corner of sec. 23, T. 48 S., R. 57 E. It is location 25 of Cobb (1972, 1978) and MAS no. 0021140074 (U.S. Bureau of Land Management, 2002). The location is accurate.|
Johnson and Karl (1985) map the rocks in the area of this prospect as Cretaceous graywacke and argillite containing sparse, lenticular beds of basalt. The rocks are cut by numerous high-angle, mainly northwest-striking faults; they include the extension of the fault at the Chichagof Mine (SI093), which controls the mineralization there and passes through this prospect.
Reed and Coats (1941) describe the Radio claims on the Bauer prospect as one or more auriferous quartz veins up to a foot thick; they are localized along a major fault and a split from it that strike northwest and dip steeply southwest. The country rock is massive, slaty graywacke with about the same strike and dip as the fault. The graywacke is intruded by a 6-foot-thick dike that locally is mineralized with pyrite and arsenopyrite. The dike and graywacke are cut by cross-joints, some of which contain quartz veinlets with pyrite and arsenopyrite. At the time of Reed and Coats' visit, the property had been explored by two tunnels, one about 270 feet long and one about 25 feet long. They do not report any assay values or production, but the extent of the workings suggests that at least some gold was recovered.ARDF record SI087 provides an overview of the geology of auriferous quartz veins in the Chichagof Mining District. Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).
|Geologic map unit||(-136.144127610776, 57.6898262855305)|
|Mineral deposit model||Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).|
|Mineral deposit model number||36a|
|Age of mineralization||Isotopic studies indicate that the gold-quartz veins in coastal southern and southeastern Alaska are Eocene, about 50 Ma in age (Haeussler and others, 1995; Goldfarb, 1997; Goldfarb and others, 1997).|
|Alteration of deposit||Dike is mineralized with arsenopyrite and pyrite.|
|Workings or exploration||The property has been explored by two tunnels, one about 270 feet long and one about 25 feet long.|
|Indication of production||Undetermined|
|Production notes||The extent of the workings suggests that at least some gold was recovered.|
Additional commentsThe prospect is in West Chichagof-Yakobi Wilderness.
Cobb, E.H., 1972, Metallic mineral resources map of the Sitka quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-467, scale 1:250,000.
Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Sitka quadrangle: U.S. Geological Survey Open-File Report 78-450, 124 p.
Goldfarb, R J., 1997, Metallogenic evolution of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 4-34.
Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Haeussler, P J., Bradley, D., Goldfarb, R., Snee, L., and Taylor, C., 1995, Link between ridge subduction and gold mineralization in southern Alaska: Geology, v. 23, no. 11, p. 995-998.
Reed, J.C., and Coats, R.R., 1941, Geology and ore deposits of the Chichagof mining district, Alaska: U.S. Geological Survey Bulletin 929, 148 p.
U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
|Reporters||H.C. Berg (U.S. Geological Survey)|
|Last report date||10/16/2004|