mineral

Selenite (gypsum) crystal

Gypsum, CaSO₄·2H₂O; transparent-to-translucent variety known as selenite

AI-generated identification · may be incorrect

Very soft (Mohs 2), white to colorless, pearly or vitreous luster, with sheet-like cleavage and a monoclinic crystal structure. The specimen appears to show a small, flattened, translucent gypsum crystal, though identification from the photo is not definitive.

Identified October 10, 2026More mineral →

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Physical properties

Formation & geological history

Gypsum forms when calcium-sulfate-rich water evaporates in arid basins, lagoons, or caves; deposits range from recent to hundreds of millions of years old.

Uses & applications

Gypsum is used in plaster, drywall, and cement; clear selenite is collected and sometimes carved for decoration.

Geological facts

Gypsum can be scratched with a fingernail and may split into thin, flexible-looking sheets, but it is not actually flexible.

Field identification & locations

Look for softness, pale color, and prominent cleavage; common deposits occur in evaporite basins worldwide, including New Mexico, Spain, and Morocco. Avoid wetting or handling roughly because it scratches and can dissolve slightly.