Halite is better known under its other name: "rock salt" Halite is made up of sodium chloride, so normal table salt. This rock type forms when oceans or saline lakes dry up and form large domes or layers of salt. This happens in very arid climates. A sea or saline lake doesn't have to dry up completely to form halite. Halite can form by precipitation from the oversaturated waterbody. Salt layers or deposits can't handle much stress or pressure so they deform into the easiest shape to deal with this stress. This has as a result that rock salt can be found in all kinds of shapes and forms in the subsurface.