Rock Identifier
White selenite (gypsum) (Gypsum, CaSO₄·2H₂O; selenite is its crystalline variety) — mineral
mineral

White selenite (gypsum)

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

AI-generated identification · may be incorrect

White to colorless, translucent, with a pearly or silky luster and monoclinic crystals; Mohs hardness 2, so it can be scratched by a fingernail. The specimen appears cloudy and roughly shaped, though the image alone cannot confirm its identity.

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Physical properties

White to colorless, translucent, with a pearly or silky luster and monoclinic crystals; Mohs hardness 2, so it can be scratched by a fingernail. The specimen appears cloudy and roughly shaped, though the image alone cannot confirm its identity.

Formation & geological history

Gypsum forms when sulfate-rich water evaporates in sedimentary basins, and also occurs in caves and hydrothermal settings. It is found in rocks of many ages; the pictured specimen’s age and locality cannot be determined visually.

Uses & applications

Used to make plaster, drywall, and cement; clear selenite is collected and sometimes carved into ornaments. It is too soft for most jewelry.

Geological facts

Gypsum contains water in its crystal structure and can be scratched with a fingernail.

Field identification & locations

Look for softness, a white streak, and distinctive cleavage; gypsum commonly occurs in evaporite deposits worldwide. The image’s stylized presentation limits reliable visual identification.