Selenite, satin spar, desert rose, gypsum flower are crystal habit varieties of the mineral gypsum. Selenite crystals show a variety of habits, but the most common are tabular, prismatic, or acicular (columnar) crystals, often with no imperfections or inclusions. Twinned crystals are common. It forms as a result of an accumulation of salt from evaporated saltwater. Gypsum is one of the most widely used minerals in the world.