mineral

Selenite (Gypsum)

Hydrous calcium sulfate (CaSO4·2H2O)

AI-generated identification · may be incorrect

Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: Colorless to white. Luster: Vitreous to pearly. Crystal structure: Monoclinic with tabular or bladed habit. Cleavage: Perfect in one direction.

Hardness: 2 on Mohs scale (can be scratched by a fingernail)
Color: Colorless to white
Luster: Vitreous to pearly

Identified May 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral in sedimentary environments such as saline lakes, lagoons, and deep-sea basins where calcium-rich water evaporates. Often found in clay beds.

Uses & applications

Used in the manufacture of drywall (plasterboard), cement, fertilizer, and as a filler in paper and paints. Transparent varieties are popular for meditation crystals and minor ornamental carvings.

Geological facts

The name 'Selenite' comes from the Greek word 'selēnitēs', meaning 'moon-stone,' because of its moon-like glow. The famous Naica Mine in Mexico contains giant selenite crystals over 36 feet long.

Field identification & locations

Identified in the field by its extreme softness (scratches with a fingernail) and its distinct tabular or bladed transparency. Commonly found in desert regions and sedimentary basins worldwide.