Hydrothermal alteration forms three mappable units. Figure 2 Figure 3 Figures 2 and 3 cover the 30 km by 35 km area within which the Goldfield and Cuprite districts lie. As labeled in Figure 2, the Goldfield district is in the upper center of the images, and Cuprite is the bright area in the bottom center. Cuprite stands out in light blue due to the prevalence of bleached, altered rocks. Alteration at Goldfield is less obvious, but might be distinguished as salmon and dark yellow colored outcrops.
Yellow areas combine minerals with both absorption features.
The Cuprite alteration zone shows up as a bright yellow oval, with red spots. Unaltered rocks are blues, dark purples, and browns.