División El Teniente[2] ("The Lieutenant") is an underground copper mine located in the Chilean Andes, 2,300 m (7,500 ft) above mean sea level.

It is in the commune of Machalí in Cachapoal Province, Libertador General Bernardo O'Higgins Region, near the company town of Sewell.

Kennecott Copper Corporation, based in Utah, United States, later operated the mine through their subsidiary company.

It was the largest mining accident in Chilean and has the highest death toll in world history associated with metal extraction.

[7] In 1967 the Chilean government bought a 51% stake in the mine and founded Sociedad Minería El Teniente.

[11] On July 11, 1971, President Salvador Allende ordered the Chilean nationalization of copper,[14] in an effort for the country to gain more benefit from the mines.

Corporación Nacional del Cobre de Chile (known as Codelco) was formed, and El Teniente became a state-owned operation.

[16] The Vancouver, British Columbia-based, Canadian company Amerigo produces both a copper and molybdenum concentrate from El Teniente's tailings.

The pipe is a geologic structure in the shape of an inverted cone, having a surface diameter of 4000 feet, and consisting of post-pipe breccia called the Braden Formation.

"[19] Mineralization at El Teniente is thought to be indebted to its position at the intersection of two large fault systems.

In 1983 El Teniente and two other Codelco mines closed when approximately 13,000 workers voted to strike "indefinitely" in protest of a union leader's arrest for calling for an end to military rule in Chile.

At least one employee was injured; he was hit by a metal object thrown by a protester on the highway leading to the mine.