Nature and origin of black chrysocolla at the inspiration mine, Arizona

A newly developed deposit at the Inspiration Mine has ore consisting of black and green chrysocolla. No primary copper minerals occur within the deposit. The chrysocolla is partly in rocks that are younger than the nearby major copper mineralization. We believe the chrysocolla was produced by reaction of soluble copper with silica dissolved from the volcanic glasses in the adjacent quartz-latite flows of the Apache Leap Formation. This is probably not a unique occurrence. Thus, chrysocolla deposits may be expected to be associated with other silica-rich flows located near sources of copper. Conversely, deposits of chrysocolla exposed at the surface may be used to locate the primary source of copper by tracing old water courses back to the primary sulfide deposits. Black chrysocolla is a manganese-rich variety of green chrysocolla (as opposed to melaconite, copper pitch, and tenorite). Its X-ray properties are indistinguishable from the green variety. Results of thermal studies show that there is a greater similarity between the green and black varieties at a given deposit, than between specimens of like color from different deposits.