Halite has the chemical formula NaCl and forms much of ordinary rock salt.
Halite is the naturally occurring mineral form of sodium chloride. It commonly crystallizes when salty water evaporates, producing cubic crystals or thick evaporite beds. Those deposits can form in enclosed seas, salt lakes and underground basins over long periods.
Pure halite is colorless or white, but impurities can make it gray, pink, blue or another color. Its cubic cleavage is a useful identifying feature: broken pieces tend to split along planes that meet at right angles. Halite is also relatively soft, with a Mohs hardness of 2.5.
Rock salt is a rock made mostly of halite, while table salt is a processed food product that may contain additives such as iodine compounds or anti-caking agents. Halite should not be confused with sylvite, the potassium-chloride mineral often mined from the same evaporite deposits.