Common salt, sodium chloride, occurs naturally in pure, solid form as the mineral halite and in widely distributed deposits of rock, or mineral, salts. It makes up almost 80 percent of the total dissolved solids in ocean water and even greater amounts in inland saltwater lakes and seas. Biologically, blood is a saline solution. The sodium component of salt operates in regulating osmotic pressures in the body and helps prevent excessive water loss. The sodium and chloride components also play a major role in the transmission of impulses in nerves.

Salt is used in greater quantities and for more applications than any other mineral. It is the primary source of sodium and chlorine, and other chemicals are produced directly from salt, including sodium hydroxide (NaOH) and hydrochloric acid (HCl). As a chemical, salt is used in the production of textile dyes, soap, glass, and pottery and to preserve leather hides. When mixed with crushed ice it acts as a refrigerant, and, spread on icy streets, it melts the ice. Table salt has been valuable for centuries in seasoning food and preserving it either by pickling or by salting down meats. Today .01 percent potassium iodine is often added to table salt (iodized) in order to supplement iodine intake in diets and thereby to prevent the disorder goiter. Excess salt intake can cause fluid retention (edema) and contribute to the circulatory disorder hypertension. Salt is produced commercially by rock-salt mining; by solar evaporation; or by solution mining, the tapping of brine wells. In rock-salt mining a vertical shaft is sunk down in a salt dome or an underground salt stratum. Parallel galleries are blasted out, leaving pillar supports for the rock salt overhead. Once hoisted to the surface the rock salt is crushed into several commercial sizes, ranging from 19-mm (3/4-in) chunks to fine powder.