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» Escondida Mine, Chile

Isolated in Chile’s northern Atacama Desert, the open-pit Escondida Mine is the world’s largest source of copper.

Escondida means “hidden” in Spanish, and hidden it was. The copper ore was buried under hundreds of meters of rock. The only way it was found was by drilling along a line of other known copper finds that stretched hundreds of kilometers.

Copper represents a substantial part of Chile’s economy. In 2013, copper mine production was valued at just over $30 billion. Chile is the world’s leading producer of copper, accounting for nearly 32% of world copper production.

Map of featured area.

Production in the Escondida Mine began in 1990. In 2012, Escondida produced just over 1 million tons of copper. Chile has approximately 24% of the world’s known copper reserves. Therefore, a multi-billion dollar expansion is planned at the Escondida Mine, which will boost production to 1.3 million tons per year and keep it at that level for the rest of the decade.

It’s easy in these images to see the extent to which the open-pit mining operation is expanding. But it’s harder to appreciate how deep the pits are. The main pit at Escondida is 645 meters deep. If you could stack two Eiffel Towers inside the pit, the top one would just barely peek over the edge.

To conserve water and minimize environmental impacts, Escondida created a tailings impoundment that has expanded along with its mining operations. The tailings material is left over after the majority of the valuable metals have been removed from the ore.

This copper-bearing waste is poured into the impoundment area as a liquid (dark region at the bottom of the 2011, 2013, and 2015 images); it dries to the lighter-toned spoil seen in the images. The spoil is held behind a retaining dam, just more than 1 kilometer long, visible in the 2011, 2013, and 2015 images as a straight line on the northwest corner of the pond.