Wollastonite typically appears as white, bladed, or fibrous masses often associated with contact metamorphism of limestone. Collectors should look for its characteristic orange fluorescence under shortwave UV light and its distinct cleavage patterns. It is frequently found in skarn environments alongside other calcium-rich silicates.
Is this wollastonite?
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 wollastonite with a known reference. Wollastonite sits at Mohs 4.5-5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, pearly on cleavage.
- 4Match the color rangeCompare against the expected color range: white, colorless, brown, red, yellow, pale green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: tabular crystals, massive, fibrous, bladed.
Often confused with
Wollastonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous, pearly on cleavage on Wollastonite and silky, subvitreous on Pectolite.
How to tell apart: Sillimanite is the harder of the two (Mohs 6.5-7.5 vs. 4.5-5).
Often found alongside wollastonite
Minerals reported to co-occur with wollastonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSiO₃
- Mohs hardness
- 4.5-5
- Density
- 2.86-3.09 g/cm³
- Streak
- White
- Luster
- Vitreous, pearly on cleavage
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Tabular crystals, massive, fibrous, bladed
- Cleavage
- {100} perfect; {001} and {102}, good; (100) ^ (001) = 84.5°
- Fluorescence
- Orange under SW UV
- Rarity
- Common
- Uses
- Collector, Industrial
- Host rock
- Common in thermally metamorphosed siliceous carbonates, the intruding igneous rock, and skarn deposits along their contact; also in some alkalic igneous rocks and carbonatites
Where rockhounds find wollastonite
4 mapped spotsClassic worldwide localities
- Natural Bridge and Diana, Lewis Co., New York, USA
- Crestmore, Riverside Co., and Darwin, Inyo Co., California, USA
- Gilbert, Esmeralda Co., Nevada, USA
- Dognecea (Dognáczka) and Csiklova, Banat, Romania
- Sarrabus, Sardinia, and from Monte Somma and Vesuvius, Campania, Italy
- Dunmorehead, Mourne Mountains, and Scawt Hill, near Larne, Co. Antrim, Ireland
Field-hunting tip
Where it forms: Common in thermally metamorphosed siliceous carbonates, the intruding igneous rock, and skarn deposits along their contact; also in some alkalic igneous rocks and carbonatites. If you start seeing calcite, grossular, diopside in float, you are in the right ground. Typical habit: tabular crystals, massive, fibrous, bladed. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, Alabama. Start trip planning there.
Common questions
How do you identify wollastonite?+
Where is wollastonite found?+
Can I find wollastonite in the United States?+
What rocks look like wollastonite?+
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Find wollastonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
