Most of the salt (sodium chloride) merchandised in America is rock salt. It is mined from existing salt deposits that were laid down ages ago by now-extinct seas. In contrast, sea salt is harvested from existing seas by trapping the saline water in tidal basin pools and taking advantage of free solar power to evaporate the water until only the salt remains. It has a stronger flavor and a more interesting character than rock salt. Sea salt's alleged nutritional superiority over rock salt, however, is nonsense. The amount of the extra trace minerals it contains is just too trifling to matter.
** Asian Recipes