Halite is the mineral form of sodium chloride, NaCl, commonly known as rock salt. Halite forms isometric crystals. The mineral is typically colorless to yellow, but may also be light blue, dark blue, and pink depending on the amount and type of impurities. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates. The rock salt is derived from the salt mountains.The rock salt occurs in vast beds of sedimentary evaporite minerals that result from the drying up of enclosed lakes, playas, and seas. Salt beds may be up to hundreds of meters thick and underlie broad areas. It is commonly used as a condiment and food preservative.