Geologic description
This prospect was found by Noranda Exploration, Inc. in 1978 (Maas and others 1991). The rocks in the area consist of a heterogeneous series of metavolcanic rocks, generally of rhyolite to latite composition, that are part of the Wales Group of Late Proterozoic and Cambrian age (Eberlein and others, 1983; Brew, 1996). The host rocks of the deposit are white to cream, metarhyolite that weathers orange and contains 1 to 2 percent pyrite. The best mineralization occurs at the base of a small waterfall, where several irregular layers and lenses of massive sulfides up to 5 inches thick are interbedded in the metarhyolite (D.J. Grybeck, unpublished field notes, 1985). The layers are mainly pyrite and sphalerite with minor chalcopyrite and galena. Selected samples of the massive sulfide layers contained 100 to 150 parts per million (ppm) silver, 0.2 to 1 percent copper, 20 to 50 ppm molybdenum, major zinc and lead, and 0.15 to 0.60 ppm gold. Similar rhyolite with thin massive sulfide lenses reportedly extends to the northwest at least as far as Polk Inlet, but the Lucky Monday deposit reportedly is the best mineralization found by industry in the area (William Block, oral communication, 1985). Maas and others (1991) collected 29 samples at or near this prospect; the best contained 51 parts per billion gold, 1.3 ppm silver, 171 ppm copper, 258 ppm lead, and 443 ppm zinc. |
