mineral

Selenite (gypsum)

Gypsum, CaSO₄·2H₂O; selenite is its transparent to translucent crystalline variety

AI-generated identification · may be incorrect

Mohs hardness 2; pale cream to colorless with pearly or silky luster and prominent cleavage. Monoclinic crystals; the specimen appears to be a rough cleavage fragment.

Identified October 1, 2026More mineral →

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Physical properties

Mohs hardness 2; pale cream to colorless with pearly or silky luster and prominent cleavage. Monoclinic crystals; the specimen appears to be a rough cleavage fragment.

Formation & geological history

Forms when sulfate-rich water evaporates in sedimentary settings, commonly in evaporite deposits; gypsum deposits range from modern to hundreds of millions of years old.

Uses & applications

Used in drywall, plaster, cement, and soil amendments; attractive selenite pieces are collected and used decoratively, though too soft for most jewelry.

Geological facts

Gypsum can be scratched with a fingernail and is soluble in water over time.

Field identification & locations

Look for softness, a pale color, and smooth cleavage faces; common deposits occur in arid basins and evaporite sequences worldwide. This specimen’s identification is visual and not definitive.