1. Regional geochemical maps of the Tonopah 1⁰?x 2⁰ quadrangle, Nevada, based on samples of stream sediment and nonmagnetic heavy-mineral concentrate Yale Public content 1988. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Branch of Distribution. English. Public. Nevada.