mineral

Gypsum (selenite/alabaster variety)

Gypsum, CaSO₄·2H₂O

AI-generated identification · may be incorrect

Likely massive gypsum with a pale cream, slightly translucent appearance and pearly to silky luster. Mohs hardness 2; monoclinic crystal system, with good cleavage and a scratchable surface.

Identified October 13, 2026More mineral →

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Physical properties

Likely massive gypsum with a pale cream, slightly translucent appearance and pearly to silky luster. Mohs hardness 2; monoclinic crystal system, with good cleavage and a scratchable surface.

Formation & geological history

Forms when sulfate-rich water evaporates in sedimentary basins, or through hydration of anhydrite. Gypsum deposits occur from many geological periods; the image alone cannot determine its age.

Uses & applications

Used to make plaster, drywall, cement additives, and fertilizer; clear selenite is also collected and carved into ornaments.

Geological facts

Gypsum is soft enough to be scratched by a fingernail and can be carved into elongated forms such as this specimen.

Field identification & locations

Common in evaporite deposits worldwide, including Spain, Mexico, and the United States. Confirm by testing softness and observing a white streak; avoid water, which can gradually damage it.