Selenite, satin spar, desert rose, and gypsum flower are four varieties of 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 a very soft mineral(hardness: 2 on Mohs Scale)
composed of calcium sulfate dihydrate (meaning has two molecules of water), with the chemical formula CaSO4·2H2O.
The most important identifying characteristic is how soft gypsum is, as any variety of gypsum can be easily
scratched with a fingernail. Also because gypsum has natural insulating properties, all varieties feel warm to the touch.
