|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||This occurrence is in a borrow pit about 0.4 mile west-southwest of the southern tip of Dora Lake; it is about 0.6 mile northeast of the center of section 35, T. 77 S., R. 87 E.|
In a borrow pit at this site, Maas and others (1991) identified mineralization similar to that at the Lucky Boy Mine (CR174), about 0.5 mile to the east. The pit exposes calcareous metasedimentary rocks and greenstone that contain stratiform quartz-calcite-sulfide veins and stringers. On older maps, these rocks were considered to be part of the Wales Group of Late Proterozoic and Cambrian age (Eberlein and others, 1983; Brew, 1996). More recent mapping, however, indicates that they are previously unrecognized Silurian and Ordovician metamorphic rocks that are less deformed than those of the Wales Group (S.M. Karl, oral communication, 2003).The prospect also includes a breccia zone about 5 feet thick that consists of rock fragments cemented by quartz and calcite with pyrite, sphalerite, and galena (Maas and others, 1991). A representative sample across the breccia contained 1,065 parts per billion (ppb) gold and 4,311 parts per million (ppm) zinc. A selected sample of sulfide-rich rock contained 6,797 ppb gold, 23.5 ppm silver, 3,210 ppm lead, and 8.87 percent zinc.
|Geologic map unit||(-132.252023871408, 55.1548857104406)|
|Mineral deposit model||Breccia zone with sulfides; possible massive-sulfide-type mineralization in the host rocks.|
|Age of mineralization||The stratiform sulfide-bearing veins may represent Silurian or Ordovician massive-sulfide-type mineralization. The sulfide-bearing breccia is epigenetic and younger.|
|Workings or exploration||Only surface sampling in a borrow pit.|
|Indication of production||None|
Brew, D.A., 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.
Eberlein, G.D., Churkin, Michael, Jr., Carter, Claire, Berg, H.C., and Ovenshine, A. T., 1983, Geology of the Craig quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-91, 52 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.
|Reporters||D.J. Grybeck (Applied Geology)|
|Last report date||5/1/2004|