mineral
Satin Spar (often marketed as Selenite)
Gypsum (CaSO4·2H2O)
AI-generated identification · may be incorrectHardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or colorless. Luster: Pearly to silky (satin-like). Crystal Structure: Monoclinic, typically fibrous. Cleavage: Perfect in one direction.
- Hardness
- 2 on Mohs scale (can be scratched by a fingernail)
- Color
- White or colorless
- Luster
- Pearly to silky (satin-like)
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Physical properties
Hardness: 2 on Mohs scale (can be scratched by a fingernail). Color: White or colorless. Luster: Pearly to silky (satin-like). Crystal Structure: Monoclinic, typically fibrous. Cleavage: Perfect in one direction.
Formation & geological history
Formed as an evaporite mineral in sedimentary environments, typically from the evaporation of seawater in ancient marine basins or in dry lake beds (playas).
Uses & applications
Used primarily for decorative carvings, metaphysical 'towers', and occasionally in the manufacture of plaster or drywall, though fibrous varieties are usually kept as specimens.
Geological facts
While commonly called 'Selenite' in the crystal trade, this fibrous white variety is technically 'Satin Spar.' True Selenite is transparent and platelike. It is one of the softest minerals on Earth and can dissolve if soaked in water for long periods.
Field identification & locations
Identify in the field by its extreme softness and silky, fibrous appearance. It is commonly found in Morocco, Mexico (Naica Mine), and the USA (Utah). Use a fingernail to test for hardness.
