Elliott M. Crist, Ellie Leavitt
Epithermal deposits were responsible for the bulk of Nevada’s precious metal production until sediment-hosted gold production gained prominence. Most Nevada epithermal deposits, such as Comstock, Tonopah and Goldfield, were discovered in the late 19th and early 20th centuries. Epithermal deposits continue to be found in our own era of exploration, and this field trip will visit some of these more modern discoveries. Most of these discoveries were prospected historically, but their full potential has only been realized within the last 25 years or so.
Epithermal deposits were originally described by Lindgren as concentrations of metals that were deposited at shallow depths and at low to moderate temperatures. Continued studies of these deposits have shown an association with igneous activity and associated hydrothermal/geothermal fluids with deposition occurring usually within 2km of the surface and at temperatures of less than 300 degrees C.
This field trip will examine deposits that formed at or relatively near the paleosurface (Wind Mountain and Hycroft) as well as deposits formed at greater depths (Sandman and Midas). An evening presentation of the Hollister Project, where both near-surface low-grade and deeper high-grade mineralization have been discovered, will enable us to examine the possibilities of bonanza deposits that may lie beneath precious metal deposits that were formed in shallow environments.
As we enjoy and learn from our visits and presentations of Wind Mountain, Hollister, Hycroft, Sandman and the Ken Snyder Mine, hopefully we will envision the many epithermal discoveries yet to be made in Nevada and elsewhere.