rocksalt

Rock salt, or halite, is the mineral form of sodium chloride (NaCl). It forms colorless to white cubic crystals and can occur in large, massive deposits. In nature it develops when saline water evaporates in enclosed basins, leaving solid salt behind. Impurities such as clay, silica, or other salts can give rock salt a pink, red, or brown hue.

Rock salt is found in sedimentary basins and evaporite deposits worldwide. It forms through long periods of evaporation under arid to semi-arid climates and is often associated with other evaporite minerals. It may occur as beds, veins, or in salt domes created by movement of salt through surrounding rock.

Mining and processing: Rock salt is extracted by conventional underground mining methods or by solution mining, in which water is injected to dissolve the salt and the resulting brine is pumped to the surface. The brine is evaporated or processed to remove impurities, and the salt is refined for use as food-grade salt or kept in coarser forms for industrial applications. Refining may produce high-purity NaCl with minimal insoluble matter and moisture.

Uses: The largest use of rock salt is road de-icing in winter. It also supplies table salt and salt for food processing, as well as salt for chemical production (notably chlorine and caustic soda), water treatment, and animal feed supplements.

Quality and varieties: Food-grade salt must meet purity standards, and many products are iodized or fortified. Rock salt used for de-icing or industrial purposes often contains insoluble impurities and moisture and is sold in coarse grains.

Safety and environmental considerations: Handling salt dust can irritate the respiratory tract; brine runoff can affect soil and water chemistry. Mining operations are regulated to manage dust, waste brine, and land rehabilitation.