mineral
Selenite (Satin Spar)
Gypsum (Calcium Sulfate Dihydrate, CaSO4·2H2O)
AI-generated identification · may be incorrectHardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or pearly. Luster: Silky/Satin. Crystal structure: Monoclinic, often fibrous. Cleavage: Perfect in one direction.
- Hardness
- 2 on Mohs scale (can be scratched by a fingernail)
- Color
- White or pearly
- Luster
- Silky/Satin
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Physical properties
Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or pearly. Luster: Silky/Satin. Crystal structure: Monoclinic, often fibrous. Cleavage: Perfect in one direction.
Formation & geological history
Formed from the evaporation of ancient seawater in saline basins (evaporite) and through hydrothermal activity. Found in sedimentary environments worldwide.
Uses & applications
Used in the manufacture of drywall (gypsum board), plaster of Paris, fertilizer, and as a popular decorative crystal in metaphysical and mineral collections.
Geological facts
Satin spar is the fibrous variety of selenite that exhibits a shimmering effect called chatoyancy. Its name comes from the Greek word 'selene' meaning 'moon,' due to its pearly glow.
Field identification & locations
Identify by its extreme softness (scratches with a fingernail) and fibrous texture. Often found in dry lake beds or as veins in clay and limestone. Keep away from water as it can erode over time.
