Digging on this open pit copper mine by Phelps Dodge began in 1951. It's located near a very rich copper area in Bisbee and it's estimated that over 1,000,000,000 tons of copper were extracted from the mine before it closed in 1974. "....Vast tonnage of dump rock is spread all around Bisbee and the southeastern Mule Mountains area. This dump material, along with the large open hole of the pit, is considered an ecological disaster by many, but, for its time, Phelps Dodge Corporation was within federal guide lines on mining codes..."