mineral
Satin Spar (Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Hardness: 2 (can be scratched by a fingernail); Color: Colorless to white; Luster: Pearly or silky; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.3
- Hardness
- 2 (can be scratched by a fingernail)
- Color
- Colorless to white
- Luster
- Pearly or silky
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 by a fingernail); Color: Colorless to white; Luster: Pearly or silky; Crystal structure: Monoclinic; Cleavage: Perfect; Specific gravity: 2.3
Formation & geological history
Formed in evaporative environments where saline water evaporates, usually in sedimentary deposits such as salt flats or clay beds.
Uses & applications
Used in the manufacture of plaster of Paris, wallboard (drywall), soil fertilizer, and commercially as a metaphysical or ornamental crystal.
Geological facts
Satin spar is often confused with 'true' selenite, which is transparent and plate-like. Satin spar is the fibrous form. It is so soft that it is extremely sensitive to water and will eventually dissolve if soaked.
Field identification & locations
Identify in the field by its extreme softness (can be scratched by a fingernail) and fibrous, silky appearance. Commonly found in Naica (Mexico), Morocco, and the Southwestern US.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous