Copper Mining in Arizona Open pit copper mining operations and workers in the American West.

The Cyprus Sierrita Copper Mine is the southernmost of three major open pit copper mines south of Tucson. It is a large open pit more than a mile wide, and 1,400 feet deep, surrounded by piles of overburden and a large tailings pond. Operated for years by the Cyprus Mineral Company, it was purchased by Phelps Dodge in 1999, which was acquired by Freeport McMoRan in 2007. Copper, and a fair amount of molybdenum have been mined here. Open pit copper mining operations and workers in the American West.