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.

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 suggested a large amount of disseminated low-grade gold thought to be more than one million ounces. Exploration also identified some higher-grade stratabound mineralization along with nearby unevaluated targets.

Exploration in the area accelerated after 2008, with efforts by several companies active in the area. The largest, Evolving Gold Corporation, eventually drilled and evaluated 252,000 ft (76,800 m) of core, finding significant gold mineralization.