mineral

Wollastonite

Calcium Inosilicate Mineral, CaSiO3

AI-generated identification · may be incorrect

Hardness of 4.5 to 5 on the Mohs scale, typically white, gray, or pale cream in color with a vitreous to pearly luster. It crystallizes in the triclinic system, features two perfect directions of cleavage, and has a specific gravity of 2.86 to 3.09.

Identified August 1, 2026More mineral →

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Physical properties

Formation & geological history

Formed through thermal metamorphism of siliceous limestones and dolostones, or through contact metamorphic processes where impure limestone interacts with hot magmatic fluids.

Uses & applications

Used widely in ceramics, paint formulation, plastics as a reinforcing filler, metallurgy as a flux, and in the manufacture of friction products like brake pads.

Geological facts

Wollastonite is named in honor of the English chemist and physicist William Hyde Wollaston. Its acicular (needle-like) crystal habit makes it an excellent industrial replacement for asbestos in certain applications.

Field identification & locations

Can be identified in the field by its characteristic bladed or acicular crystal aggregates, white color, and association with skarn deposits in contact metamorphic zones.