Geologic description
The rocks in the area are Upper Jurassic or Cretaceous marine argillite and graywacke, interbedded with andesite or basalt (Brew and Ford, 1985). The bedded rocks are regionally metamorphosed to prehnite-pumpellyite or greenschist grade, and cut by diorite or gabbro dikes and sills. The deposit was discovered in 1888 and developed by a 1,040-foot adit and a 415-foot adit. The facilities included an 80-stamp mill, a tram, wharfs, and dock facilities. The recorded production is 2 ounces of gold (Redman and others, 1989). The rocks at the prospect are black phyllite, felsic phyllite, greenstone, and very-fine-grained augite metagabbro or diabase. The strata strike northwest and dip moderately northeast. The felsic phyllite is composed of quartz, muscovite, and feldspar. The unit is several hundred feet thick; has 1 to 3 percent disseminated pyrite, and is cut by small quartz veins with sphalerite, galena, and chalcopyrite, and traces of gold and silver. The U.S. Bureau of Mines suggests that this prospect is similar to the Alaska Treasure massive sulfide deposit (JU228) (Redman and others, 1989; Wells and others, 1986). |
