The chemical formula of wollastonite is Ca3〔Si3O9〕, where  calcium is often replaced by iron, manganese or magnesium. Wollastonite belongs to triclinic system. It mostly appears in flaky, radial, fibrous or massive aggregate. The color is white to grey white, sometimes with yellow or green brown color; glassy luster; the cleavage plane appears pearl color. Hardness: 4.5-5; specific gravity: 2.87-3.90. Wollastonite often appears in the contact metamorphic zone of impure limestone and acid intrusive rocks, which is the main mineral component of skarn. It also appears in some deep metamorphic rocks.