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Chemical Formula | CaSiO3 | ||||||
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Composition | Calcium silicate | ||||||
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Color | White, cream, gray, light yellow, pink; very pale shades of green and brown | ||||||
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Streak | White | ||||||
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Hardness | 4½ - 5 | ||||||
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Crystal Forms and Aggregates |
(Triclinic) Rarely occurs in single crystals, which are tabular and often twinned. Usually occurs fibrous, massive, radiating, grainy, bladed, as cleavage fragments, and as compact groupings of elongated tabular crystals. | ||||||
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Transparency | Translucent | ||||||
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Specific Gravity | 2.8 - 2.9 | ||||||
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Luster | Vitreous, silky | ||||||
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Cleavage | 1,2 - pinacoidal, similar to that of the pyroxene minerals | ||||||
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Fracture | Uneven, splintery | ||||||
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Tenacity | Brittle | ||||||
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Other ID Marks | Usually fluorescent yellow, orange, or white | ||||||
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Varieties |  Manganowollastonite - Light
pink, manganese-rich variety of Wollastonite, with
manganese partially replacing the calcium. Formula = (Ca,Mn)SiO3 Ferrowollastonite
- Gray or brown, iron-rich variety of Wollastonite, with
iron partially replacing the calcium. Formula = (Ca,Fe)SiO3 |
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Polymorphs | Wollastonite occurs in three different
forms, depending on crystallization. Common Wollastonite is
scientifically known as Wollastonite 1A,
indicating that it is one form of Wollastonite that
crystallizes in the triclinic system. The "1A" distinguishes
it from two rarer forms of Wollastonite (which are
scientifically different minerals since they crystallize differently): Wollastonite 2M
and Wollastonite 7A. Wollastonite 2M
crystallizes in the monoclinic system, and Wollastonite 7A in the triclinic system but forms different crystals than
Wollastonite 1A. (Wollastonite 7A is scientifically divided into four additional minerals which are almost identical. They are Wollastonite 3A, 4A, 5A, and 7A) Other names are given to these forms of Wollastonite:
Both Wollastonite 2M and Wollastonite 7A are very rare. Virtually all Wollastonite specimens are Wollastonite 1A. |
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In Group | Silicates ; Inosilicates | ||||||
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All About | Wollastonite was named after William Hyde Wollaston (1766-1828), a British chemist and physicist noted for his inventions in optics. | ||||||
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Uses | Wollastonite is an industrially important mineral. It is a necessary ingredient in heat-resistant refractory ceramics and is used as a filler in paint. It is also used in the manufacture of paper and plastics. | ||||||
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Striking Features | Cleavage angle, crystal habit, and fluorescence | ||||||
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Complex Tests | Dissolves in hydrochloric acid | ||||||
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Popularity (1-4) | 2 | ||||||
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Prevalence (1-3) | 2 | ||||||
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Demand (1-3) | 1 | ||||||
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Distinguishing Similar Minerals |
Tremolite - different cleavage angles Pectolite - crystals more compact, usually occurs in a different environment than Wollastonite |
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Commonly Occurs With |
Calcite, Grossular, Vesuvianite, Diopside, Epidote | ||||||
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Noteworthy Localities |
Two famous European occurrences of Wollastonite are Pargas, Finland, and Monte Somma, Vesuvius, Italy. In Canada, it is found in the Jeffery Mine, Asbestos, Quebec. U.S. localities include the Crestmore Quarry, Riverside Co., California; the Lone Pine Mine, Independence, Inyo Co., California; Natural Bridge, St. Lawrence Co. and Diana, Lewis Co., New York; and Franklin, Sussex Co., New Jersey. | ||||||
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Picture Icon Links |
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| Picture Links | 1. Wollastonite
crystal grouping 2. Radiating Wollastonite |
