The Geology and Metal Resources of the Black Hills Uplift, Wyoming

Abstract Nonradioactive metal resources in the Black Hills uplift of Wyoming include gold, copper, silver, lead, zinc, tin, manganese, niobium, tantalum, vanadium, and rare earths. The majority of these occurrences are associated with Tertiary alkalic igneous complexes in the Bear Lodge Mountains, Black Buttes, and Mineral Hill districts. Vanadium (which was once mined with uranium) is found in Cretaceous sandstones along the western margin of the uplift. Gold anomalies have been reported in at least one of these uranium-vanadium deposits, as well as in Cretaceous coal, and in sandstone from the Cambria area along the southern flank of the uplift. Based on the available information, the most interesting deposits are the low-grade gold and rare earth deposits hosted by 38-to 55-million-year-old fenitized alkalic igneous rock of the Bear Lodge Mountains, and the placers surrounding Mineral Hill which contain anomalous amounts of gold, cassiterite, magnetite, and columbite-tantalite (Hausel, 1988).