Description: Sierrita is an open pit metals mine and concentrator, with molybdenum by-products.

Did you know? One of the safest mines in the United States, having earned the federal government’s prestigious ‘Sentinels of Safety’ award as the safest open-pit mine in the open-pit hard-rock mine category in 1993, 1997, 1999 and 2001. In addition to copper and molybdenum, the mine produces rhenium, a rare and highly valued metal.

Location: 20 miles southwest of Tucson, near Green Valley, Arizona.

Ores: The predominant oxide copper minerals are malachite, azurite and chrysocolla. Chalcocite is the most important secondary copper sulfide mineral, and chalcopyrite and molybdenite the dominant primary sulfides.

Processes and facilities: SX/EW plant, concentrator, molybdenum roasting plant and rhenium processing facility.

Background: First claims recorded in 1895. First worked as an underground mine beginning in 1907; open-pit development began in 1957. Sierrita became part of the Phelps Dodge mining portfolio in 1999 and a part of Freeport-McMoRan in 2007.

Ownership: 100%.

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