Mine Tales: Copper isn’t the only mineral common in Arizona – by William Ascarza (Arizona Daily Star – November 4, 2013)


In 2012, Arizona produced more than $2 billion in nonfuel mineral commodities. While Arizona leads the nation in copper production, additional minerals ranked according to value include molybdenum concentrates, sand and gravel (construction), cement (portland) and silver.

Industrial minerals found in Arizona include sand, gravel, limestone, clay, marble, gypsum, asbestos, perlite, talc, zeolites and landscape rock.

Industrial minerals mined in Arizona such as sand and gravel produced from flood plains, washes and alluvial fans are used in the construction of highways, airports, buildings, dams and bridges.

Gravel and aggregate (a combination of rocks and sand used in the manufacture of concrete) are the most common industrial minerals in Arizona. One hundred tons of sand and gravel are needed in the construction of a standard 1,600-square-foot house.

Limestone, also abundant in Arizona, is used in the manufacture of portland cement. More than 400 active mines exist in Arizona, many of them involved in quarrying industrial minerals.

Portland cement originated from the portland stone commonly used in late 18th century England. It consists of limestone mixed with bauxite, clay, sand and shale and was used to build the Eddystone Lighthouse off Cornwall, England.

As the oldest continually producing portland cement company west of the Rocky Mountains, California Portland Cement was founded in 1891 with the opening of a plant in Colton, Calif. Subsidiary plants were later established, including one in Mojave, Calif., and one in Rillito.

The California Portland Cement Co. recognized the need to expand its market into Arizona during the 1890s. However, market conditions, capital and location prevented such a move until half a century later.

Land surveys conducted by California Portland Cement near the town of Rillito in the 1920s found a sizable limestone deposit. The first cement plant in Arizona was built by the Portland Cement Co. at Rillito in 1949 at a cost of $3 million on 200 acres.

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