Areas in green have minerals that are more neutral but are still of concern. The mineral colors are overlain on an aerial photo base to aid in locating the potential acid generating areas. Note bright areas of waste rock and tailings piles where no detected acid-generating minerals were found. Image is about 6 km across. Idealized Acid-Mineral Assemblage Bull's Eye.
Secondary minerals form roughly concentric zones around pyrite-rich areas at the surface.
They have pyrite or jarosite in the center surrounded by a goethite-jarosite zone, in turn surrounded by either goethite or hematite forming bull's eyes around the hot spots of pyrite oxidation. These patterns can be used to locate point-sources of acid mine drainage at Leadville and probably at other mined and unmined areas by marking areas of low pH and potential trace metal mobility. Since mineralization was hosted in limestones on both sides of the fault, the differences in alteration may be related to changes in the chemistry and temperature of the hydrothermal fluids or the composition of the waste rock. These spectrally observed compositional differences may, nevertheless, fingerprint waste rock piles as originating from specific mines or ore bodies. At present, no clear relationship can be drawn between the distribution of clays and the location of acid drainage point-sources.