mineral
Clear selenite (gypsum)
Gypsum, CaSO₄·2H₂O; selenite is its transparent to translucent crystalline variety
AI-generated identification · may be incorrectColorless to milky white with a pearly or vitreous luster and visible cleavage; monoclinic crystals, Mohs hardness 2, specific gravity about 2.3. The pictured rough piece appears consistent with gypsum, though a photo cannot confirm the identification.
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Physical properties
Colorless to milky white with a pearly or vitreous luster and visible cleavage; monoclinic crystals, Mohs hardness 2, specific gravity about 2.3. The pictured rough piece appears consistent with gypsum, though a photo cannot confirm the identification.
Formation & geological history
Forms when sulfate-rich water evaporates in arid basins or from hydrothermal processes; deposits range from recent to hundreds of millions of years old.
Uses & applications
Used to make plaster, drywall, and cement; clear, attractive crystals are collected and sometimes used decoratively, but the mineral is too soft for most jewelry.
Geological facts
Gypsum can be scratched with a fingernail and may split into thin sheets along cleavage planes.
Field identification & locations
Look for very low hardness, pale color, and a silky or pearly cleavage surface; common in evaporite deposits worldwide, including Spain, Mexico, and the United States.
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