mineral
Satin Spar (Selenite)
Calcium sulfate dihydrate (CaSO4·2H2O)
AI-generated identification · may be incorrectHardness: 2 (can be scratched with a fingernail); Color: Pearly white to translucent; Luster: Silky or pearly; Crystal Structure: Monoclinic (fibrous); Cleavage: Perfect; Specific Gravity: 2.3
- Hardness
- 2 (can be scratched with a fingernail)
- Color
- Pearly white to translucent
- Luster
- Silky or pearly
Identified More mineral →
Explore Satin Spar (Selenite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 2 (can be scratched with a fingernail); Color: Pearly white to translucent; Luster: Silky or pearly; Crystal Structure: Monoclinic (fibrous); Cleavage: Perfect; Specific Gravity: 2.3
Formation & geological history
Formed in evaporite environments where sea water or saline lake water evaporates. It can also form through the oxidation of sulfides in hydrothermal veins.
Uses & applications
Used in gypsum wallboard (drywall), plaster of Paris, soil conditioners, and as a popular ornamental stone for carvings and metaphysical collections.
Geological facts
Satin spar is often confused with 'true' Selenite, which is the transparent, plate-like variety of gypsum. It is famous for its fiber-optic qualities, where light travels along the length of the internal fibers.
Field identification & locations
Identify by its extreme softness and distinctive silky, fibrous appearance. Look for it in sedimentary basins and arid regions such as Morocco or the Southwestern USA.
