El Salvador's economy is entirely based on copper mining. The Atacameños extracted copper from this area for more than a thousand years. Nevertheless, it was American explorations in the 1950s that revealed the presence of ore that could be exploited in an industrial scale. Anaconda Copper Mining Company was concerned about declining reserves in its Potrerillos mine and it sent prospectors in search of a new Chilean ore body in 1951. Working under the auspices Anaconda's Andes Mining subsidiary, the mineralization was discovered in 1954 and mapped in 1955.