salt

Salt is a mineral composed primarily of sodium chloride (NaCl). It occurs naturally as halite and is the most widely used source of edible salt. Crystals are typically colorless or white, though impurities can give pink, gray, or blue hues.

Salt forms when salty waters evaporate or when mineral-rich brines are concentrated in sedimentary basins. Seawater contains dissolved salts, about 3.5% by weight, with sodium chloride accounting for most of that salinity. Deposits known as rock salt or halite accumulate in ancient evaporite basins and are mined for commercial use.

Commercial salt is produced by mining underground rock salt deposits or by evaporating seawater or brines in solar or mechanical ponds. After harvesting, the salt is refined to remove insoluble matter and, in many countries, iodized to supply dietary iodine. Anti-caking agents may be added to keep it free-flowing.

Salt has many uses: as a flavor enhancer and preservative in food, as a chemical feedstock for chlorine and caustic soda production, for de-icing roads, and in water conditioning and various industrial processes.

There are many varieties, including table salt, sea salt, kosher salt, and rock salt. Some are iodized to prevent iodine deficiency; others are treated to achieve specific textures or flavors.

Sodium from salt is essential in small amounts but excessive intake is associated with hypertension and cardiovascular disease. Many dietary guidelines advise limiting sodium intake and choosing iodized salt where iodine deficiency is a concern.

Salt has been traded for millennia and has played a central role in food preservation, cuisine, and industry. Its availability shaped economies and influenced maritime exploration and urban development.