mineral

Satin Spar Selenite

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or pearly. Luster: Pearly to silky. Crystal structure: Monoclinic, often fibrous. Cleavage: Perfect in one direction. Specific Gravity: 2.3.

Hardness: 2 on Mohs scale (can be scratched by a fingernail)
Color: White or pearly
Luster: Pearly to silky

Identified April 1, 2026More mineral →

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Physical properties

Formation & geological history

Formed as an evaporite mineral from the evaporation of seawater in ancient basins, or through the hydration of anhydrite. Found in sedimentary environments.

Uses & applications

Used in the drywall industry (as gypsum), as a soil conditioner, in plaster of Paris, and widely sold as 'cleansing' crystals in metaphysical and decorative markets.

Geological facts

The name 'Selenite' is derived from the Greek word for 'moon' because of its pale, moon-like glow. The Naica Mine in Mexico contains giant selenite crystals over 30 feet long.

Field identification & locations

Identify by its extreme softness (scratches with a fingernail) and silky, cat's-eye like chatoyancy when light reflects off its fibrous structure. Commonly found in deserts or dry lake beds.

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