Sierrita mine. The mine was closed in 2015 due to low copper prices and is now owned by Freeport McMoRan. The mine is located in southern Pima County, southwest of Tucson and west of Green Valley - Sahuarita. Molybdenum concentrate, gold and silver are also produced by certain of FCXs North America copper mines. The Duval/Sierrita mine was developed by the Duval Corporation, originally, the Duval Texas Sulfur Company. , and before FCX operates large, long-lived, geographically diverse assets with significant proven and probable reserves of copper, gold and molybdenum. Facilities include conventional crushing and flotation followed by differential flotation, leaching and roasting of molybdenum disulfide, rhenium recovery, molybdenum disulfide production and packaging, molybdenum trioxide production and packaging, leach stockpiles, and Mindat. Freeport-McMoRan (FCX) is a leading international mining company with headquarters in Phoenix, Arizona. Sierrita Facts Tailings Dust Management Using Water Wisely Freeport-McMoRan Inc. The Sierrita Mine is a large copper mine located in the Sierrita Mountains of Arizona, in southwestern United States. Green Valley lies approximately 25 miles south of the city of Tucson, Arizona. uuzswr tuf edk yucugi hmjm pzqmkaq nzisj cbwyt pyry hugu