Hourglass selenite crystals are found only on the salt plains of Oklahoma, a unique 11,000-acre geological area. The salt plains were formed by repeated flooding by sea water millions of years ago.
Selenite (hydrous calcium sulfate) is a crystallized form of gypsum, a common mineral in sedimentary environments that can take on a great variety of crystal forms and shapes. Crystals take on the characteristics of their environment - iron oxide in the soil gives the hourglass crystals their chocolate brown color.
