mineral
Selenite
Gypsum (CaSO4·2H2O)
Mohs hardness of 2 (very soft, can be scratched with a fingernail), white to colorless, pearly to vitreous luster, monoclinic crystal system, perfect cleavage in one direction yielding thin flexible sheets, specific gravity of 2.3
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Physical properties
Mohs hardness of 2 (very soft, can be scratched with a fingernail), white to colorless, pearly to vitreous luster, monoclinic crystal system, perfect cleavage in one direction yielding thin flexible sheets, specific gravity of 2.3
Formation & geological history
Formed as an evaporite mineral from the precipitation of calcium sulfate in evaporating bodies of water, such as ancient seas and salt lakes, often occurring in sedimentary environments.
Uses & applications
Widely used in decorative items, crystal healing, carving, and historically in the manufacturing of plaster of Paris.
Geological facts
Selenite is a crystalline variety of the mineral gypsum. The name comes from the Greek word 'selinites', meaning 'moon stone', due to its pearly, moon-like glow.
Field identification & locations
Easily identifiable by its extreme softness (Mohs 2) and fibrous or transparent appearance. Common locations include Mexico (Naica Mine), Morocco, and the United States.
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