Book an order today for Flat Massage wands Selenite Moon Phase. Selenite, also known as satin spar, desert rose, or gypsum flower are four crystal structure varieties of the mineral gypsum. These four varieties of gypsum may be grouped together and called selenite. Selenite is a variety of gypsum occurring in transparent crystals or crystalline masses. The salt was formed by the repeated flooding of seawater millions of years ago. It is the concentrated saline solution combining with the gypsum that promotes the selenite crystal growth in a portion of the salt flats. Selenite is a crystallized form of gypsum. Chemically, it is a hydrous calcium sulfate.