
mineral
Satin Spar (Selenite)
Gypsum (Calcium Sulfate Dihydrate, CaSO4·2H2O)
AI-generated identification · may be incorrectHardness: 2 (Mohs scale), Color: White to colorless, Luster: Pearly or silky (chatoyant), Crystal Structure: Monoclinic, Cleavage: Perfect, Specific Gravity: 2.3
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Physical properties
Hardness: 2 (Mohs scale), Color: White to colorless, Luster: Pearly or silky (chatoyant), Crystal Structure: Monoclinic, Cleavage: Perfect, Specific Gravity: 2.3
Formation & geological history
Formed in evaporite deposits in sedimentary basins where saline water evaporates, often found in clay beds or around hot springs.
Uses & applications
Commonly used in carving, drywall manufacturing, plaster of Paris, and widely sold as 'cleansing' crystals in the metaphysical market.
Geological facts
Satin spar is often mislabeled simply as 'Selenite' in trade; true selenite is the transparent variety, while satin spar is the fibrous/silky variety. It is soft enough to be scratched by a fingernail.
Field identification & locations
Identifiable by its silky luster and extreme softness. Common in Morocco, Mexico, and the USA. Collectors look for long, undamaged fibrous wands.