White (1955a) reported that the lower workings of the Cordero Mercury Mine (Sec. 33, T47N, R37E) were noticeably hot, on the order of 30-35°C, but no precise temperature measurements were taken. Reed and others (1984, p. 40) reported a spring south of the mine to have a temperature of 56ºC with an estimated reservoir temperature of 110ºC. White also mentioned that the level of oxidation in the mine was between the 150- and 183-m level. Water wells down slope from the mine have temperatures of up to 140 F (Visher, 1957) at depths of 120-180 m. Isotopic analysis of the well waters indicated a strong dominance by water of meteoric origin (White, 1974). A well in Sec. 17, T47N, R38E, 9 km northeast of the Cordero Mine, has a reported temperature of 32°C.