Geologic descriptionThe general area is underlain mainly by Silurian and Devonian graywacke and argillite and Middle Devonian carbonate, clastic and volcanic rocks (MacKevett and others, 1971; Brew and others, 1978). The country rocks at this prospect are Silurian graywacke and Devonian and Silurian greenstone intruded by small bodies of Cretaceous quartz monzonite and syenite (Clough and Redman, 1989). The Lucky Six prospect was first discovered in the 1950s, when a radioactive anomaly was detected from the air by prospectors. The deposit has been explored by shallow pits, trenches, and one diamond-drill hole. The drilling was conducted by a private contractor supported by a Federal grant. One sample was reported to contain 0.20 percent eU (equivalent uranium), but a commercial deposit was not indicated (Clough and Redman, 1989). Two pits on the Lucky Six prospect expose zones containing soft, vuggy, black-and red-stained fractured material. No well-defined veins are visible, but a prominent fracture in pit No. 2 strikes N 5 E and dips 80 W. The intrusive country rock is light-gray porphyry containing feldspar crystals up to 1.5 inches long. The porphyry contains abundant altered mica, especially noticeable on fractures and in vugs. Brecciated, fine-grained, siliceous rock crops out 150 feet southwest of pit No. 1. This rock may be the extension of a crushed zone in that pit. Traces of thorianite and scattered grains of euxenite have been reported, and rare-earth elements occur in a sample containing pyrite, chalcopyrite, galena, and sphalerite (Eakins, 1975). |
