Salt Mining

Salt, NaCl (sodium chloride), is an ionic compound made of sodium and chloride ions. All life depends on its chemical properties to survive. It has been used by humans for thousands of years, from food preservation to seasoning. Salt's ability to preserve food was a founding contributor to the development of civilization.

Prior to industrialization, it was expensive, dangerous, and labor intensive to harvest the mass quantities of salt needed for food preservation and seasoning. This made salt an extremely valuable commodity in ancient times. Entire economies were based solely on salt production and trade. Salt was a highly valued trade item, and was considered a form of trade currency.

While bulldozing salt from the Chehrabad Salt Mine, Iranian miners uncovered the sixth "salt man". These are ancient corpses killed or crushed in the cave and mummified by the extreme conditions. Hair, flesh and bone are all preserved. Even internal organs such as stomachs and colons have been found intact. The first salt mummy, dated to 300 A.D., was discovered in 1993, sporting a long white beard, iron knives and a single gold earring. The oldest saltman found dates to about 550 BC.

Ancient method of boiling brine into pure salt in China.

In the Iron Age, the British evaporated salt by boiling seawater or brine from salt spri­ngs in small clay pots over open fires. Roman salt-making entailed boiling seawater in lead-lined pans. In ancient Rome, salt on the table was a mark of a very rich patron; those who sat nearer the host were "above the salt," and those less favored were "below the salt".

The oldest salt mine known in Azerbaijan.

Italy has no salt deposits. Rome produced salt via solar evaporation (salinae) along the coast and by boiling seawater in lead pans. In Dacia by 160 AD the Romans built deep, highly engineered underground salt mines, including at Potaissa. Potaissa (modern-day Turda, Romania) was a major Roman settlement and legionary fortress. It was the stronghold of the elite and legendary Legio V Macedonica.

Ancient Roman Glass Salt Dishes

The Roman salt trade was a driving force behind the empire's economic and military power. The state closely controlled its production and taxed its distribution. Salt was a vital component in Rome's production of garum and for preserving meat and fish to feed Roman legions. Roman prisoners were given the task of salt mining, and life expectancy was extremely low. Rapid dehydration caused by constant contact with the salt and accidental excessive sodium intake was fatal.

Roman salt pans in Hortales.

Roman soldiers were given a special allowance to purchase salt. Known as a salarium, this is the exact origin of the word "salary". From the Edict of Maximum Prices issued in 301 by Diocletian, 1 modius of salt (8-9 kg) cost 100 denarii, about the same as wheat or lentils.