Selenite (mineral)
Selenite, satin spar, desert rose, and gypsum flower are four varieties of the mineral gypsum; all four varieties show obvious crystalline structure. The four "crystalline" varieties of gypsum are sometimes grouped together and called selenite.
All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning has two molecules of water), with the chemical formula CaSO4ยท2H2O. Selenite contains no significant selenium; the similarity of names comes from both substances being named from the Ancient Greek word for the Moon.
Read more about Selenite (mineral): History and Etymology, Identification of Crystals As Gypsum, Varieties, Use and History, Crystal Habit and Properties, Occurrence, Images