Chuquicamata (chōˌkēkämäˈtä) [key], former town, Antofagasta region, N Chile, on the western slopes of the Andes. At an elevation of 10,435 ft (3,181 m), the location is the site of the world's largest copper mines. The extensive open-pit mining of the region dates to 1915. Smelting and flotation plants began operations in 1951; an expansion of refining plants in 1970 substantially increased copper output. In 2003, due to the expansion of the mine and environmental problems, the town was evacuated and its buildings removed; many residents moved to nearby Calama.