The Rattlesnake Hills in central Wyoming are a partially exposed fragment of a synformal Archean greenstone belt that was intruded during the Tertiary by alkalic volcanic rocks (Hausel, 1996). In 1982, the WSGS discovered anomalous gold in the Rattlesnake Hills in pyrite-rich metachert. Hausel (1996) recognized a minimum of three episodes of gold mineralization, including syngenetic stratabound exhalative mineralization, epigenetic mineralization, and disseminated epithermal gold associated with Tertiary volcanic activity. Exploration in the area by several companies between 1983 and 1993 demonstrated more than one million ounces of disseminated low-grade gold. Exploration also identified some higher-grade stratabound mineralization along with nearby unevaluated targets. Interest in the Rattlesnake Hills gold continues to the present, with recently reported drilling activity.
Goat Mountain Tertiary stock behind ridge of varied Precambrian rocks, with light colored
Miocene Split Rock Formation in middle-ground, southwestern Rattlesnake Hills.
Further information on the Rattlesnake Hills can be found in the following WSGS publications:
WSGS Report of Investigations 52, Geology and gold mineralization of the Rattlesnake Hills, Granite Mountains, Wyoming, by W. Dan Hausel (1996), map scale 1:24,000, 28 p.
WSGS Map Series 67, Geologic map of the Barlow Gap Quadrangle, Fremont County, Wyoming (Link to Geologic Mapping page), by Wayne M. Sutherland, and W. Dan Hausel (2005). map scale 1:24,000.
WSGS Mineral Report 2002-2, Preliminary Geologic Map of the Rattlesnake Hills 1:100,000-scale Quadrangle (Link to Geologic Mapping page), by Wayne M. Sutherland, and W. Dan Hausel (2002), 28 p.