Satin Spar
Satin Spar is a fibrous variety of gypsum recognized by its silky sheen, white to cream color, and soft hardness.
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Satin Spar properties at a glance
| Type | Minerals |
|---|---|
| Chemical formula | CaSO4·2H2O |
| Mohs hardness | 2 |
| Crystal system | monoclinic |
| Luster | silky |
| Streak | White |
| Cleavage | Perfect |
| Fracture | Fibrous |
| Specific gravity | 2.3 |
| Transparency | translucent |
| Common colors | White, Cream, Colorless, Peach |
| Rarity | common |
Geology & background
Forms as fibrous gypsum in evaporite deposits, fractures, or veins where calcium sulfate crystallizes from mineral-rich water.
Satin Spar is widely used in mineral collecting, decorative carvings, and the crystal trade as a gypsum variety.
How to identify Satin Spar
- Look for silky fibrous bands and white to cream translucency.
- Confirm softness; gypsum scratches easily with a fingernail.
- Do not confuse fibrous satin spar with clear platy selenite crystals.
Where Satin Spar is found
Satin Spar gypsum is reported from many evaporite localities; exact locality should be verified from specimen provenance.
How much is Satin Spar worth?
| Entry-level specimen | $5 |
|---|---|
| Typical collector specimen | $20 |
| Premium specimen | $120+ |
Value depends on size, condition, color, pattern, locality, preparation, and provenance. Treat this as educational guidance, not an appraisal.
Common uses
- Decorative objects
- Carvings
- Collector specimens
- Educational specimens
Interesting facts
- Many retail pieces labeled selenite towers are actually satin spar gypsum.
- The silky shimmer comes from parallel fibrous crystals.
- It is soft enough to scratch with a fingernail.
Care & safety
Treat Satin Spar as a collector specimen unless hardness, cleavage, and fracture are confirmed.
Avoid inhaling dust. Do not cut, grind, or polish unknown specimens without eye protection and a properly rated respirator.
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