Key facts
- Category
- Sulfate mineral
- Formula
- CaSO 4 ·2H 2 O
- Crystal system
- Monoclinic (2/m) Space group: A2/a
- Color
- Colorless, often tinted due to inclusions , Satin spar gypsum: white
- Crystal habit
- Platy , Satin spar gypsum: fibrous
- Cleavage
- Perfect, Distinct, Distinct
- Fracture
- Micaceous , Satin spar gypsum: fibrous
- Luster
- Vitreous , Satin spar gypsum: pearly
- Streak
- White
- Diaphaneity
- Transparent , Satin spar gypsum: translucent to opaque
- Optical properties
- Biaxial (+) 2V=58
- Refractive index
- nα = 1.519–1.521, nβ = 1.522–1.523, nγ = 1.529–1.53
- Birefringence
- δ = 0.0090–0.0100
- Other characteristics
- Fluorescent
via Wikipedia infobox
~10 min read
Encyclopedic overview
Selenite is a mostly clear, transparent variety of the sulfate mineral gypsum.
The name selenite is also commonly used for other varieties of gypsum, including satin spar gypsum, desert roses, and gypsum flowers.
Excerpted from Wikipedia’s “selenite” article, available under the CC BY-SA 4.0 licence.