Aucanquilcha, Stratovolcano in Antofagasta Region, Chile

Aucanquilcha is a stratovolcano in the Antofagasta Region near the Chilean-Bolivian border, rising to 6,176 meters above sea level. The mountain displays a ridge-like profile and sits within the Alto Loa National Reserve, with an abandoned mining camp positioned at 5,280 meters.

Sulfur mining at Aucanquilcha began in 1913, run by S. I. A. M. Carrasco S. A., then Chile's second-largest sulfur company. Until 1935 llama caravans carried the sulfur down; that year a 13.6 km aerial cableway opened, from a valley station at 3,942 m to a mountain station at 5,874 m. The mine closed in 1992.

The summit area holds two ceremonial circles left by the Incas, who regarded the mountain as a shrine; remains of yareta plants processed as fuel were found beside them. The mine workforce was exclusively Quechua Indians from Bolivia, the only people accustomed to working above 5,500 m.

The access road built in 1972, with many switchbacks, is now impassable because of rock falls. The mine road on the south side, from a camp at 4,778 m on the B-105, is likewise cut by landslides. Meltwater from the snow and ice cover, which reaches down to about 5,500 m, is not drinkable.

In 1986 four men were reported living at 5,900 m on Aucanquilcha, then the highest permanent residents on Earth, which drew scientific attention. The workers were Quechua Indians from Bolivia, considered the only people accustomed to such altitudes. Their camp, Campamento Aucanquilcha, stood at 5,334 m.