Halite more commonly known as Rock salt is a mineral formed from sodium chloride. It's chemical formula is NaCl and this also includes other variations of salt such as common salt and table salt. Rock salt tends to be the industrial name used for Halite.
Food grade rock salt can be used for cooking, just like refined iodised salt. The amount of salt added needs to be adjusted according to taste. Some chefs also use this salt to give their food an eggy flavour without using eggs.