The Pioche mining district in the Ely Range, southeastern Nevada, is one of several districts in the Great Basin where Cambrian rocks are hosts of important ore deposits. Cambrian strata underlying the Ely Range are intruded by porphyritic granite and other dikes. Tertiary volcanic rocks and Pliocene fresh-water clastic deposits of the Panaca Formation occupy adjacent valleys and extend over the Cambrian strata on the south and east.