Aucanquilcha (pronounced: OW-kahn-KEEL-chuh) is a massive stratovolcano located in Antofagasta Region of northern Chile, just west of the border with Bolivia. It comprises a number of overlapping cones along a 10 km (6 mi) long ridge that forms the summit. There is weak, episodic fumarolic activity and voluminous sulfur deposits in the summit region. During the Pleistocene ice ages, an extensive ice cap with an area over 45 km² (17 mi²) mantled the upper slopes, extending down as low as 4,600 m (15,000 ft) and leaving large moraines. The aridity of the region today, however, means that no glaciers exist even though the mountain extends well above the altitudinal line of continuous permafrost.
Abandoned sulfur workings near the summit of Aucanquilcha
A sulfur mine, owned by the Carrasco family, was located near the summit of Aucanquilcha, which was the world's highest mine until it closed in the 1990s, and it was serviced by perhaps the highest driveable road in the world, but this road is no longer usable by vehicles. The highest permanent human habitation was a miners' barracks at about 5,500 m (18,000 ft). Mining originally began on the volcano in 1913, initially using llamas as pack animals to carry down the sulfur. An aerial cable system extending for 22 km (14 mi) was completed in 1935, to lower the sulfur in buckets. Eventually this was replaced by the road which switchbacked up to the summit and was capable of supporting 20-ton mining trucks.