The McCoy Geothermal Prospect (Olson and others, 1979) is an apparently blind geothermal area discovered by favorable hydrogeochemical analyses of well waters and anomalous thermal gradients . The area of anomalous subsurface temperatures is about 20 km long and over 5 km wide, in T22-24N, R39-40E. The thermal anomaly is in the mountain range. A fossil mound of travertine 10 m thick and covering 2 km² is located in unsurveyed NW¼ T23N, R40E just west of the McCoy (mercury) Mine (Olson and others, 1979). The water chemistry from a warm well at the McCoy Mine suggests a minimum equilibration temperature of 186ºC with an 85% cold-water fraction (Olson and others, 1979). Subsurface temperatures as high as 40.4ºC were measured at a depth of 48 m. A temperature-gradient drill hole drilled by Phillips Petroleum, to 149 m, reported a bottom-hole temperatures of 38.3ºC (GeothermEx, 2004). Location: 39.83ºN, 117.50ºW.