The Morenci mine is the largest copper producing mine in North America and remains a major contributor to Freeport-McMoRan’s copper output, which is second only to that of Chile’s Codelco. Phelps mined underground until the 1930s depression, converting to an open-cut operation with rail haulage in 1937. The topography prevented development as a single pit: today the working area extends across 2.5km x 2.2km but is worked as three pits: the Metcalf (within the original Morenci pit), the NWX (Northwest Extension) and the Coronado.
Author: Jim Hefer