Professional Paper, Issues 65-67

abundant alaskite altered alunite andesite augite basalt Basin beds Belle Fourche biotite bismuthinite Black Butte Black Hills breccia Canyon clay Columbia Mountain contains Creek crystals dacite dacite vitrophyre Dakota Deadwood deposits depth east erosion eruptions exposed extends famatinite fault feet thick feldspar fissures Florence flow geologic gold Goldfield Goldfield district gray groundmass hornblende igneous rock intrusive irregular kaolinite Kendall kilometers laccolith lake Lakota Lakota sandstone landslide latite lava lease ledge matter limestone mass material meters microscope miles Milltown Milltown andesite mineral mines Minnelusa Mohawk Morena rhyolite Nevada northeast northwest occurs outcrops oxidized pay shoots Peak phenocrysts plagioclase portion probably pyrite pyroxene quartz region rhyolite ridge rock streams Sandstorm rhyolite sandy shale sediments shaft shale shows slope soft southeast Spearfish stope sulphide Sundance surface Survey Tertiary thin Tonopah tuff U. S. Geol uplift Valley vicinity Vindicator Mountain volcanic Whitewood