Copper mining in Arizona

Copper mining in Arizona, a state of the United States, has been a major industry since the 1800s. In 2006 Arizona was the leading copper-producing state in the US, producing a record five billion dollars worth of copper. Copper mining also produces gold and silver as byproducts. Byproduct molybdenum from copper mining makes Arizona the nation's second-largest producer of that metal.

Although copper mineralization was found by the earliest Spanish explorers of Arizona, the territory was remote, and copper could not be profitably mined and shipped. Early Spanish, Mexican, and American prospectors searched for gold and silver (see Silver mining in Arizona), and ignored copper. It was not until the completion of the Southern Pacific Railroad in 1876 that copper became broadly economic to mine and ship to market.

All copper mining was by underground methods until the early 20th century. After the Bingham Canyon mine in Utah successfully mined a large low-grade copper deposit from a large open pit, the same technique was applied to Arizona’s porphyry copper deposits. Arizona's first open pit copper mined opened at Ajo in 1917.

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Jerome

Native Americans used copper minerals of the Verde district at modern-day Jerome as pigment to decorate skin and textiles. The first European to visit the area is thought to be Spanish explorer Antonio de Espejo, who found silver at a location in central Arizona in 1583. No mining resulted, and Juan de Oñate led another expedition searching for Espejo’s silver location in 1598; many claims were staked, but the expeditioners returned to Santa Fe without mining any silver, and the deposits remained unexploited.^[1]

The United Verde mine exhausted the rich oxidized ores in 1884, and the mine closed. William A. Clark of Montana visited the district in 1888, bought it, and reopened the mine. The smelter at Clarkdale was built in 1915.^[2]

Ajo

Spaniards mined on a small scale at Ajo as early as 1750. After the Gadsden Purchase brought the southern Arizona into the United States in 1853, Americans reopened the mine in 1855, and shipped high-grade ore to Swansea in Wales.

Clifton-Morenci district

Prospectors from Silver City, New Mexico discovered copper mineralization at Morenci, also known as the Greenlee district in 1872. Mining began the following year, and Miners extracted and smelted high-grade copper ore until a railroad reached the district in 1884 and a concentrator made mining and processing of low-grade ore economical.^[3]

Bisbee

An army scout noted copper mineralization in the Warren district at present-day Bisbee in 1877. Production began in 1880 after a rich discovery of copper carbonate on the Copper Queen claim. The success of the Copper Queen mine convinced Phelps Dodge to buy the adjacent Atlantic claim in 1881. Phelps Dodge later bought control of the Copper Queen and adjacent claims. The company started mining the Lavender Pit in the early 1950s.^[4]

Globe-Miami

Silver mining started at Globe in 1874. The silver mines shut down in 1877, but the following year copper mining took over.^[5]

White Mesa district

The White Mesa copper-mining district is in the western part of the Navajo reservation, 112 miles northeast of Flagstaff, in Coconino County. The copper deposits consist of malachite and chrysocolla as grain coatings in the Jurassic Navajo Sandstone. They were first mined on a small scale by Mormon settlers in the 1800s, then briefly in 1917, and again 1939-1941. The district produced about 550,000 pounds of copper and a small amount of silver.^[6]

Copper mining today

As of 2006, there were 11 producing copper mines in Arizona.

• Cochise County: Bisbee mine;
• Gila County: Pinto Valley mine and Miami mine;
• Greenlee County: Morenci mine;
• Mohave County: Mineral Park mine;
• Pima County: Mission mine, Silver Bell mine, and Sierrita mine;
• Pinal County: Ray mine and Tohono mine;
• Yavapai County: Bagdad mine.

Six of the mines are owned and operated by Phelps Dodge, three by Asarco, and one each by BHP Billiton and Mercator Minerals.^[7]

In addition to its existing mines, Phelps Dodge is preparing its new Safford Mine, eight miles north of the town of Safford in Graham County to begin producing copper in 2008. The Safford mine, in a large porphyry copper deposit, will be the largest new copper mine put on production in Arizona in more than 30 years.^[8]

References