Satin spar
Variety CaSO4·2H2O
Also called Fibrous gypsum
Take care.
- Damaged by water: Keep it dry: don't wash it, and keep it out of damp places.
- Fragile: Handle it gently and pack it well; it breaks or crumbles easily.
About it
Fibrous gypsum in parallel veins with a silky, moving sheen. Morocco supplies most of the bars and towers sold as selenite; water ruins its polish. The name is also used for fibrous calcite.
- Type
- Variety
- Group
- Gypsum variety
- Formula
- CaSO4·2H2O
- Hardness (Mohs)
- 2
- Specific gravity
- 2.31–2.33
- Streak
- white
- Lustre
- silky
- Crystal system
- Monoclinic
- Colours
- white, pinkish, pale orange
- Transparency
- translucent
- Cleavage and fracture
- perfect in one direction; thin flakes bend but do not spring back
Typical values: real specimens vary. For more, see mindat.org.