Located between Winkelman and Superior along scenic Highway 177, the Ray mine has a history dating back 140 years.

The Ray Mining District, also known as the Mineral Creek Mining District, was organized in 1873. Silver prospecting took precedence there over the next decade. However, it took several years of prospecting the area before its ore potential was realized because accessibility to the area was such a challenge.

The Mineral Creek Mining Co. built a five-stamp mill there in 1880, spurring an increase in mining interests in the district.

The Ray Copper Mines Ltd., a British firm, was established in 1899 and bought mining claims in and around Ray, north of what is now Florence.

The town of Kelvin began in 1877 as a post office and stage station called Riverside.

The name was changed to Kelvin in 1900. It briefly served as the Ray Copper Mines Ltd. reduction works and office headquarters and had a peak population of 1,000. Two hundred thousand tons of ore were processed, but because of a miscalculation of ore that ran 2 percent instead of the expected 4 percent, the company failed.

Because of its proximity to the Gila River to dispose of waste, a smelter was built in Hayden by the American Smelting and Refining Co. (Asarco) in 1910. A mill and smelter operated at the site to process the ore mined at Ray.

Large-scale underground mining started at Ray the following year.

During World War I, the town of Ray, built in 1909, experienced a population boom of 5,000, and construction included two banks and a newspaper, the Copper Camp. According to a 1936 report, the Ray district produced $280,000 worth of gold between 1911 and 1931.

The mine property underwent several ownerships, including those of Calumet Copper, Gila Copper and Arizona Hercules before the Kennecott Copper Corp. assumed control at Ray in 1933.

In 1955, the Ray mine completed a conversion from underground workings to open-pit mine operations. The father of open-pit mining, Daniel C. Jackling, had been involved in exploratory work at Ray nearly 50 years earlier.

Large low-grade, disseminated copper deposits are the primary metal mined at the Ray mine. Other metals that have been mined there include molybdenum, silver, gold, lead and zinc.

The planned town of Kearny was built in the late 1950s by the Kennecott Mining Co. as a way to relocate miners and their families who lived in the local communities of Sonora, Ray and Barcelona. These small towns were destined to be engulfed by the eminent domain of the emerging open-pit mine.

Concentrating and smelting facilities continue at Hayden, 17 miles southeast of the Ray mine. The Copper Basin Railway transports ore from the mine to the processing facilities at Hayden, which include a 27,400-ton-per-day concentrator and a 720,000-ton-per-year smelter, where more than 380 tons of copper are refined every day to a purity of 99 percent.

The finished product — 750-pound, 3-inch-thick rectangular slabs called copper anodes — are shipped by rail to a copper refinery in Amarillo, Texas, for final processing.

Hayden produced 318.1 million pounds of anodes in 2012. Today the open-pit mine is operated by Asarco, which extracts 250,000 tons of ore daily with projected ore reserves until 2044.

Sources: Asarco Ray Operations: www.ascarco.com; Bulletin 169, The Mineral Industries of Arizona, 1962; Peirce, H. Wesley. Geologic Guidebook 2-Highways of Arizona; Arizona, Highways 77 and 177; Arizona Bureau of Mines Bulletin 176, 1967; Ransome, Frederick L. The Copper Deposits of Ray and Miami, Arizona, U.S. Geological Survey Professional Paper 115; Seefeldt, Douglas. Creating Kearny: Forging a Historical Identity for a Central Arizona Mining Community; Journal of Arizona History 46:1 (Spring 2005); Sloane, Howard N. and Lucille L. 1970; A Pictorial History of American Mining From Pre-Columbian Times to the Present Day; Elsing, Morris J. and Robert E.S. Heineman; Arizona Metal Production; Arizona Bureau of Mines, Economic Series No. 19 Bulletin No. 140, 1936.

Email archivist and historian William Ascarza at mining@azstarnet.com