Halite is true salt, which consists of sodium chloride (NaCl). This is the same chemical long used as flavoring on food & as a preservative. It has a nonmetallic luster, typically clearish/coloress, and is relatively soft (H = 2.5). Halite forms cubic crystals and has cubic cleavage (= 3 cleavage planes meeting at 90º angles). Halite is most readily identified by its strongly salty taste.
Halite has economic value. In addition to its use in food, salt is traditionally used in large quantities in wintertime to prevent roadways from icing up. Halite is principally mined from ancient rock salt successions. Rock salt is a chemical sedimentary rock composed of halite and formed by evaporation of seawater. Northeastern Ohio has significant & economic subsurface concentrations of rock salt (halite) of Silurian age.
Halite (~1 to ~2 cm across each)
Halite (each ~2 to ~4 mm in size) - small masses of modern lacustrine evaporitic halite crystals from Grosbeak Lake Salt Flats, SSW of town of Fort Smith, far-northern Alberta Province, western Canada.
Hopper halite from Trona, California, USA. The edges of halite crystals can grow more quickly than the faces, resulting in a series of depressed faces. Such crystals are called "hopper crystals".
(Dwyer Mercer County District Library #223-550, Celina, Ohio, USA).
Blue halite, a rare color variety (left: 2.6 cm across; right: 2.9 cm across). The blue coloration is the result of radiation from potassium-40 in nearby potash salts. Irradiation ultimately results in excess free sodium metal in the halite, turning it blue. These come from the Prairie Evaporite Formation (upper Elk Point Group, Middle Devonian) of the Potash Saskatchewan-Lanigan Mine (PCS-Lanigan Mine, near Lanigan, south-central Saskatchewan, Canada).