mineral
Wollastonite
Calcium Inosilicate, CaSiO3
Hardness of 4.5 to 5 on the Mohs scale, color typically white, off-white, grey, or pale green. Luster is vitreous to pearly. Crystal structure is triclinic, commonly forming tabular crystals or cleavable to fibrous masses.
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Physical properties
Hardness of 4.5 to 5 on the Mohs scale, color typically white, off-white, grey, or pale green. Luster is vitreous to pearly. Crystal structure is triclinic, commonly forming tabular crystals or cleavable to fibrous masses.
Formation & geological history
Formed through thermal metamorphism (contact metamorphism) of siliceous limestones and dolomites, where high temperatures cause the reaction of calcite with silica.
Uses & applications
Used widely in ceramics, polymers, paint, friction products (as an asbestos substitute), and metallurgy as a flux.
Geological facts
Wollastonite is named after the English chemist and mineralogist William Hyde Wollaston. Its acicular (needle-like) crystal habit makes it an excellent reinforcing filler in industrial applications.
Field identification & locations
Found in skarn deposits associated with intrusive igneous rocks altering limestone. Identified by its typical white fibrous or bladed habit, good cleavage, and association with other contact metamorphic minerals like garnet and diopside.
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