Get Happy. A good handful. Made of gypsum. They seem like a bar of shiny, slick soap. Pretty. The light goes through it wonderfully. Verging on fragile. AND allegedly they are water soluble. Al that time in the desert. Selenite is a crystallized form of gypsum that's mostly commonly found in the form of a translucent, multifaceted stone. It's formed when sulfate and calcium-rich saltwater evaporates, and it has a hardness of 2 on the Mohs scale.