mineral

Likely selenite (transparent gypsum) crystal cluster

Gypsum, CaSO₄·2H₂O; selenite is its clear crystalline variety

AI-generated identification · may be incorrect

White to colorless, translucent, with a glassy-to-pearly luster and prominent cleavage; Mohs hardness 2, monoclinic crystal system, specific gravity about 2.3. The photo does not show enough detail for a certain identification.

Identified October 14, 2026More mineral →

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Physical properties

Formation & geological history

Gypsum forms when sulfate-rich water evaporates or through hydration of anhydrite, commonly in sedimentary basins; deposits range from recent to hundreds of millions of years old.

Uses & applications

Used to make plaster, drywall, and cement; clear crystals are collected and sometimes used decoratively, but are too soft for durable jewelry.

Geological facts

Selenite is exceptionally soft and can be scratched with a fingernail; it is not the same mineral as satin spar, another gypsum variety.

Field identification & locations

Check for soft, easily scratched material and flat cleavage surfaces; common deposits occur in evaporite beds worldwide, including the Great Salt Plains of Oklahoma and Naica, Mexico. Image-based identification is tentative.