Pseudowollastonite is a high-temperature polymorph of CaSiO₃ that forms under specific contact metamorphic conditions. It is typically found in altered limestone xenoliths within volcanic rocks, often appearing as glassy, tabular crystals that are difficult to distinguish from common wollastonite without laboratory analysis.

Hardness

4.5-5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareWollastonite Group family

Pseudowollastonite

Hardness: 4.5-5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this pseudowollastonite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch pseudowollastonite with a known reference. Pseudowollastonite sits at Mohs 4.5-5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Pseudowollastonite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Pseudowollastonite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, gray.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, massive.

Often confused with

Pseudowollastonite vs. its common look-alikes — and how to tell them apart in the field.

Often found alongside pseudowollastonite

Minerals reported to co-occur with pseudowollastonite. 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: 2.90 g/cm³
Colors: White Colorless Gray
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals, Massive
Cleavage: Good
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Metamorphosed Limestone
Typical price: $20-100 per specimen

Where rockhounds find pseudowollastonite

Classic worldwide localities

Scawt Hill, Northern Ireland
Kilchoan, Scotland
Velardena, Mexico
Bellerberg, Germany

Field-hunting tip

Look in metamorphosed limestone country — that is the host setting where pseudowollastonite typically forms. If you start seeing larnite, merwinite, gehlenite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify pseudowollastonite?+

Mohs hardness is 4.5-5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, gray.

Where is pseudowollastonite found?+

Notable localities include Scawt Hill, Northern Ireland; Kilchoan, Scotland; Velardena, Mexico; Bellerberg, Germany.

How much is pseudowollastonite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like pseudowollastonite?+

Pseudowollastonite is most often confused with Wollastonite, Rankinite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with pseudowollastonite?+

Pseudowollastonite commonly co-occurs with Larnite, Merwinite, Gehlenite, Spurrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pseudowollastonite form in?+

Pseudowollastonite typically forms in metamorphosed limestone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is pseudowollastonite used for?+

Pseudowollastonite is used in collector, scientific research.

Find pseudowollastonite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.