Selenite is a fibrous, translucent form of gypsum. The fissure surfaces are glassy to pearly shiny. It is precisely from his "lunar" gloss that his name selenite is derived, according to the Greek goddess Selene. Gypsum, chemically calcium sulfate (CaSO4), is a widely distributed mineral. Most of the gypsum originated in the distant past when seawater dries in shallow bays and lagoons. In addition to gypsum positions, deposits of rock salt or anhydrite have also been formed in this way. Along with these minerals, calcite precipitated from sea water, the sediments, often full of fossil remains of various fauna and flora, formed of a rock called limestone. Among the most famous selenite deposits are Morocco.