Satin Spar is a fibrous, silky variety of gypsum that exhibits a distinct chatoyancy or cat's-eye effect when polished. It is typically found in sedimentary evaporite beds, often occurring as compact, parallel fibrous veins.
Is this satin spar?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch satin spar with a known reference. Satin Spar sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Satin Spar leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Satin Spar typically shows a silky luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous.
Often confused with
Satin Spar vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside satin spar
Minerals reported to co-occur with satin spar. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSO₄·2H₂O
- Mohs hardness
- 2
- Density
- 2.3 g/cm³
- Streak
- White
- Luster
- Silky
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous
- Cleavage
- Perfect in One Direction
- Rarity
- Common
- Uses
- Collector, Lapidary, Decorative
- Host rock
- Sedimentary Evaporite Deposits
- Typical price
- $5-30 per specimen
Where rockhounds find satin spar
1 mapped spotsClassic worldwide localities
- United Kingdom
- USA
- Mexico
- Poland
- Italy
Field-hunting tip
Look in sedimentary evaporite deposits country — that is the host setting where satin spar typically forms. If you start seeing anhydrite, halite, sulfur in float, you are in the right ground. Field specimens usually show a fibrous habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico — start trip planning there.
Common questions
How do you identify satin spar?+
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Find satin spar on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
