mineral

Selenite tower

Selenite (transparent to translucent gypsum), CaSO₄·2H₂O

AI-generated identification · may be incorrect

Mohs hardness 2; white to colorless, pearly or vitreous luster, monoclinic crystals, and perfect one-directional cleavage. The elongated polished form shows fibrous satin-spar texture and translucency.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms when evaporating saline or groundwater precipitates hydrated calcium sulfate, commonly in sedimentary evaporite beds; individual crystals may grow over thousands to millions of years. This specimen has been cut and polished into a tower.

Uses & applications

Used decoratively and collected for its glow and fibrous texture; gypsum is widely used in drywall, plaster, cement, and fertilizer. Selenite is generally too soft for durable jewelry.

Geological facts

Despite its glasslike appearance, it is very soft and scratches easily with a fingernail. “Selenite” is a variety name for clear or translucent gypsum, not a separate mineral species.

Field identification & locations

Identify by its white translucency, silky fibers, softness, and easy cleavage; avoid water because prolonged exposure can dull or dissolve the surface. Common sources include Morocco, Mexico, the United States, and Spain.