A salt mine is a mining operation involved in the extraction of rock salt or halite from evaporite deposits.[1]
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Areas known for their salt mines include Kilroot near Carrickfergus, Northern Ireland (over 100 years old with more than 25 km of passages); Khewra and Warcha in Pakistan; Tuzla in Bosnia; Wieliczka and Bochnia in Poland (both established in the mid-13th century and still operating, mostly as museums); Hallstatt and Salzkammergut in Austria; Rheinberg in Germany; Slănic, Cacica, Ocnele Mari, Salina Turda, Târgu Ocna, Ocna Sibiului, and Praid in Romania; Provadiya in Bulgaria; Racalmuto, Realmonte and Petralia Soprana[2] within the production sites managed by Italkali in southern Italy; Avery Island in Louisiana, United States; the wich towns of Cheshire and Worcestershire in England; and the Detroit Salt Company's 1,500-acre (10 km2) subterranean complex 1,100 feet (340 m) beneath the city of Detroit.[3] The Sifto Salt Mine in Goderich, Ontario, Canada is one of the largest salt mines in the world. It measures 1.5 miles (2.4 km) wide and 2 miles (3.2 km) long.[4]
Prior to the advent of the internal combustion engine and earth moving equipment, mining salt was one of the most expensive and dangerous of operations. While salt is now plentiful, before the Industrial Revolution salt was difficult to come by, and salt mining was often done by slave or prison labor. In ancient Rome, salt on the table was a mark of a rich patron (and those who sat nearer the host were above the salt, and those less favored were "below the salt"). Roman prisoners were given the task of salt mining, and life expectancy among those so sentenced was low. The Roman historian Pliny the Elder stated as an aside in his Natural History's discussion of sea water, that "[I]n Rome ... the soldier's pay was originally salt and the word salary derives from it ..."[5] However, this is disputed by modern historians (see notes in salary).
Even as recently as the 20th century, salt mining in the Soviet Union and Nazi Germany was performed by persons being punished.
Today most salt mines are operated by large multi-national companies like Cargill and Compass Minerals.