Wollastonite
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| Wollastonite | |
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Missing image WollastoniteUSGOV.jpg Wollastonite | |
| General | |
| Category | Mineral |
| Chemical formula (or Composition) | Calcium silicate, CaSiO3 |
| Identification | |
| Color | white, colorless or gray |
| Crystal habit | rare tabular crystals - commonly massive in lamellar, radiating, compact and fibrous aggregates. |
| Crystal system | triclinic bar 1 |
| Cleavage | perfect in two directions at near 90 degrees |
| Fracture | splintery to uneven |
| Mohs Scale hardness | 5 - 5.5 |
| Luster | vitreous or dull to pearly on cleavage surfaces |
| Refractive index | a=1.615-1.646, b=1.627-1.659, g=1.629-1.662 |
| Pleochroism | - |
| Streak | White |
| Specific gravity | 2.8 - 2.9 |
| Melting point | - |
| Solubility | soluble in HCl |
Wollastonite is a calcium inosilicate mineral (CaSiO3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolostone is subjected to high temperature and pressure sometimes in the presence of silica-bearing fluids as in skarns or contact metamorphic rocks. Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, and calcite. It is named after the English chemist and mineralogist William Hyde Wollaston (1766-1828).
In the United States, wollastonite is mined in Willsboro, New York. China is the leading producing country. Some of the properties that make wollastonite so useful are its high brightness and whiteness, low moisture and oil absorption, and low volatile content. Wollastonite is used primarily in ceramics, friction products (brakes and clutches), metalmaking, paint filler, and plastics.
See also
References
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0471805807
- Mindat (http://www.mindat.org/min-4323.html)
- Webmineral (http://webmineral.com/data/Wollastonite-1A.shtml)
- Mineral galleries (http://mineral.galleries.com/minerals/silicate/wollasto/wollasto.htm)Template:Mineral-stub