mineral

Satin Spar (Gypsum)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

AI-generated identification · may be incorrect

Hardness: 2 on Mohs scale; Color: Grayish-white, translucent; Luster: Silky to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in one direction, displaying fine fibrous parallel striations.

Hardness: 2 on Mohs scale
Color: Grayish-white, translucent
Luster: Silky to pearly

Identified July 25, 2026More mineral →

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Physical properties

Hardness: 2 on Mohs scale; Color: Grayish-white, translucent; Luster: Silky to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in one direction, displaying fine fibrous parallel striations.

Formation & geological history

Formed as an evaporite mineral in lake and marine settings where mineral-rich water evaporates, or through hydrothermal deposition in veins.

Uses & applications

Used widely in ornamental carvings, polished wand/slabs for metaphysical crystal collecting, plaster manufacture, and drywall production.

Geological facts

Satin spar is often mistakenly sold as 'selenite'. While both are varieties of gypsum, satin spar exhibits a fibrous structure that gives it a silky luster and chatoyancy (cat's-eye effect), whereas selenite forms clear, flat, sheet-like crystals.

Field identification & locations

Can be identified by its soft surface easily scratched by a fingernail and distinct parallel fibrous texture. Commonly found in Morocco, USA, Mexico, and England.