The open pit of the Mission Mine south of Tucson is 2 miles long by 2 miles wide and is 1,500 feet deep. The copper mine operates 24 hours a day, 365 days a year. The mine is 18 miles south of Tucson.

Courtesy of Asarco

It seems like mining has always been big in Arizona. In 1736 the discovery of silver just below the current border with Mexico drew prospective Spanish miners northward into Southern Arizona. After Arizona became a U.S. territory, gold was found near Yuma in 1858 and in 1863 in the Bradshaw Mountains near Prescott and around Wickenburg. By that time about 1 of every 4 people in the territory was a miner.

Tombstone’s boom in the 1880s was based on silver, but Arizona’s precious metals were soon exhausted and it became evident that Arizona’s long-term mining prosperity depended on copper.

Copper history

Copper is easily stretched, molded and shaped, is resistant to corrosion, and conducts heat and electricity efficiently. The discovery that copper combines with tin to produce bronze marked the beginning of the Bronze Age about 3000 B.C.

Native Americans used copper in Arizona a thousand years ago for pigments, ornaments and tools. The first Spanish explorers here in the 1500s found working copper mines.

Spaniards mined copper on a small scale at Ajo as early as 1750. After the Gadsden Purchase in 1854, the mine was reopened by Anglos.

In the 1870s and 1880s, huge copper deposits were found in Bisbee, Clifton-Morenci, Globe-Miami and Jerome. “Big-time towns” sprang up to support serious mining operations. Copper emerged as the most important mineral to the economy of Arizona.

Other early successful copper operations included the Ray Mine (Pinal County), the Bagdad Mine (Yavapai County) and mines near Tucson at Silver Bell (23 miles northwest) and Sierrita (20 miles southwest), and forerunners of the Mission Mine (18 miles south).

By 1910 Arizona was the leading producer of copper in the U.S., and it remains so today.

Copper mining

Copper mining started out as an underground operation, with access to the copper ore via vertical shafts and tunnels. Over the years, the decline of the richness of the ore forced miners into open-pit mining, where vastly larger bodies of ore had to be dug out and processed to achieve significant amounts of copper.

The first open-pit copper mine in Arizona was in Ajo in 1917. By the 1950s, most Arizona copper mines were open-pit operations.

Miners continued to find additional sources of copper. Since the mid-1950s, new sites included San Manuel (25 miles northeast of Tucson), Mineral Park (Mohave County), Pinto Valley (Gila County), Carlotta (Globe-Miami) and most recently at Safford (Graham County).

Some early mines closed after they ran out of profitable ore, with their supporting towns, such as Bisbee and Jerome, “rapidly shrinking to the brink of nonexistence,” but finding new life as popular artist colonies and tourist attractions.

Copper mining operations also eventually closed at Ajo and San Manuel, resulting in less successful “second lives.” Other former copper towns, in central Arizona (east of Phoenix), have formed the Copper Corridor, a movement to attract tourism to their mining history.

Other copper mining operations are still open and producing today. The top 10 largest producers (in rank order of output) in 2012 were Morenci, Ray, Bagdad, Safford, Sierrita, Mission, Miami, Silver Bell, Mineral Park and Carlota.

To see how a modern open-pit copper mine operates, you can tour Asarco’s Mission Mine in Sahuarita.

Copper today

Today copper is used in a variety of domestic, industrial and high-technology applications, including in building construction, power generation and transmission, electronics manufacturing and the production of industrial machinery and transportation vehicles.

Familiar products made using copper include semiconductors, cellphones, computer chips and automobiles.

Despite some mine closings, declining yields at some sites and fluctuating copper prices, Arizona remains a major copper producer. According to the Arizona Mining Association, in 2012 Arizona mines produced 1.63 billion pounds of copper valued at $6.02 billion. That was 65 percent of all the copper produced in the U.S., and more than 10,500 people were employed in mining and refining copper.

Arizona is also the second-largest U.S. producer of molybdenum, which is extracted as a byproduct of copper, and is fifth in the nation for producing silver, mined mostly as a product of copper processing.

Plans for new mining to satisfy future copper requirements are underway. These include Rosemont Copper, 30 miles southeast of Tucson, now in the permitting process under the direction of the United States Forest Service, and Resolution Copper, near Superior, currently stalled pending a proposed land swap with the federal government.

Copper certainly remains a core industry of the Arizona economy.

Bob Ring is a longtime Southern Arizonan and avid historian. E-mail him at

Selected sources and information: “Arizona — A History” (Thomas E. Sheridan, 2012); Economic Impact of the Mining Industry on Arizona — 2012, Arizona Mining Association; Facts About Copper,; Five C’s Supported the Arizona Economy,; A History of Mining in AZ,; Mining Arizona, The Arizona Experience; Rosemont Plan — Mine Plan of Operations, WestLand Resources Inc.; U.S. Bureau of Economic Analysis, Gross Domestic Product by State, 2013; Wikipedia: Copper Mining in Arizona, Resolution Copper, Rosemont Copper, Safford Mine, San Manuel Copper Mine, Seal of Arizona.