Salar de Uyuni (or "Salar de Tunupa") is the world's largest salt flat, or playa, at over 10,000 square kilometers in area. It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of 3,656 m above sea level.
The geological history of the Salar is associated with a sequential transformation between several vast lakes. Some 30,000 to 42,000 years ago, the area was part of a giant prehistoric lake, Lake Minchin. Its age was estimated by radiocarbon dating shells from outcropping sediments and carbonate reefs and varies between reported studies. Lake Minchin (named after Juan B. Minchin of Oruro) later transformed into Paleo Lake Tauca having a maximal depth of 140 meters, and an estimated age of 13,000 to 18,000 or 14,900 to 26,100 years, depending on the source.
The Salar was formed as a result of transformations between several prehistoric lakes that existed around forty thousand years ago but had all evaporated over time. It is now covered by a few meters of salt crust, which has an extraordinary flatness with the average elevation variations within one meter over the entire area of the Salar. The crust serves as a source of salt and covers a pool of brine, which is exceptionally rich in lithium. The large area, clear skies, and exceptional flatness of the surface make the Salar ideal for calibrating the altimeters of Earth observation satellites. Following rain, a thin layer of dead calm water transforms the flat into the world's largest mirror, 129 km across.
Located in the Lithium Triangle, the Salar contains a large amount of sodium, potassium, lithium and magnesium (all in the chloride forms of NaCl, KCl, LiCl and MgCl2, respectively), as well as borax. No mining plant is currently at the site, and the Bolivian government does not want to allow exploitation by foreign corporations. Instead, it intends to reach an annual production of 35,000 t by 2023 in a joint venture with ACI Systems Alemania GmbH. With an estimated 9,000,000 t, Bolivia holds about 7% of the world's known lithium resources; most of those are in the Salar de Uyuni.
Salar de Uyuni is estimated to contain 10 billion tonnes of salt, of which less than 25,000 t is extracted annually. All miners working in the Salar belong to Colchani's cooperative. Because of its location, large area, and flatness, the Salar is a major car transport route across the Bolivian Altiplano, except when seasonally covered with water.
Salar has been used as a filming location for movies such as Star Wars: The Last Jedi (2017; as planet Crait), The Fall (2006), Salt and Fire (2016), The Unseen (2017), and several others.
According to Wikipedia