At an elevation of some 14,000 ft., the El Indio mine in Chile was from 1980 - 2000 + or -, the richest gold and copper mine in South America. It was prospected from the air; geologists were drawn by the rich tapestry of colors. The colors are a consequence of the hydrothermal alteration of the host rock and the precipitation of minerals brought to the surface dissolved in hot volcanic fluids. High-grade ore contained 11 oz. of gold per ton. Copper and a buffet of other minerals are extract