The mine is located in the town of Santa Rita, 15 miles east of Silver City. The huge open-pit mine was once the largest in the world (see Chuquicamata) and is perhaps the oldest mining site still being used in the American southwest. Apaches, Spaniards, Mexicans, and Americans have all obtained native copper and copper ore from this site, once known as the Santa Rita mine, and in the 1800s, a tunnel mine. The present-day open-pit mining operation was begun in 1901.
A mill to process the low-grade copper ore was established in nearby Hurley in 1911. Milling operations recently (January 2004) restarted at the Chino Concentrator after a three-year hiatus caused by low copper prices. Reserves of copper ore at Chino are expected to last until 2008.
External link
Mining in the Southwest (http://www.epcc.edu/ftp/Homes/monicaw/borderlands/21_mining.htm) - includes a brief history of the Chino Mine
Open-pit mining, or opencast mining, refers to a method of extracting rock or minerals from the earth by their removal from an open pit or borrow.
Open-pit mines are used when deposits of commercially useful minerals or rock are found near the surface; that is, where the overburden (surface material covering the valuable deposit) is relatively thin or the material of interest is structurally unsuitable for tunneling (as would be the case for sand, cinder, and gravel).
Copper is extracted at grades as low as 0.15% to 0.2%, generally in massive open cut mines in Chile, where the size of the resources and favorable metallurgy allows economies of scale.