page_title: Wollastonite
section_title: Substitutes
hierarchical_section_title: Wollastonite / Substitutes
caption_attribution_description: English: Wollastonite Locality: Libušin, Kladno, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic White acicular xls of Wollastonite. Field of view 8 mm. Depth of field is achieved with CombineZM. Specimen and photo Leon Hupperichs. Deutsch: Wollastonit
context_page_description: Wollastonite is a calcium inosilicate mineral that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns or in contact with metamorphic rocks. Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, pyroxene and calcite. It is named after the English chemist and mineralogist William Hyde Wollaston.
  Some of the properties that make wollastonite so useful are its high brightness and white coloration, low moisture and oil absorption, and low volatile content. Wollastonite is used primarily in ceramics, friction products, metalmaking, paint filler, and plastics.
  Despite its chemical similarity to the compositional spectrum of the pyroxene group of minerals—where magnesium and iron substitution for calcium ends with diopside and hedenbergite respectively—it is structurally very different, with a third SiO₄ tetrahedron in the linked chain.
context_section_description: The acicular nature of many wollastonite products allows it to compete with other acicular materials, such as ceramic fiber, glass fiber, steel fiber, and several organic fibers, such as aramid, polyethylene, polypropylene, and polytetrafluoroethylene in products where improvements in dimensional stability, flexural modulus, and heat deflection are sought.
  Wollastonite also competes with several nonfibrous minerals or rocks, such as kaolin, mica, and talc, which are added to plastics to increase flexural strength, and such minerals as barite, calcium carbonate, gypsum, and talc, which impart dimensional stability to plastics.
  In ceramics, wollastonite competes with carbonates, feldspar, lime, and silica as a source of calcium and silicon. Its use in ceramics depends on the formulation of the ceramic body and the firing method.
caption: White acicular crystals of wollastonite (field of view 8 mm) from the Central Bohemia Region, Czech Republic
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