Wollastonite
Wollastonite is a calcium inosilicate mineral with the chemical formula CaSiO3. It is named after the English chemist and mineralogist William Hyde Wollaston (1766–1828), who first described the mineral in 1818 from a specimen found in Chesterfield, England.
Physical Properties
- Color: White, gray, or colorless; may be tinted pink or green by impurities.
- Crystal System: Triclinic
- Cleavage: Perfect in two directions
- Fracture: Uneven
- Hardness: 4.5 - 5.0 on the Mohs scale
- Luster: Vitreous to pearly
- Streak: White
- Specific Gravity: Approximately 2.8 to 3.0
Occurrence
Wollastonite is commonly found in contact metamorphic zones where limestone or marble has been altered by silica-rich solutions or by contact with igneous intrusions. Major deposits are located in:
Uses
Wollastonite has several industrial applications due to its chemical composition and physical properties:
- Ceramics: Used in ceramic bodies to reduce thermal expansion, increase strength, and improve resistance to thermal shock.
- Paints and Coatings: As a filler to enhance the opacity, brightness, and durability of paints.
- Polymers: Added to plastics to improve mechanical properties, thermal stability, and fire resistance.
- Metallurgy: As a flux in steelmaking to aid in the removal of impurities.
- Environmental Applications: Used in soil stabilization, as a pH buffer, and in the remediation of heavy metal contamination.
Historical Context
The mineral was initially recognized for its use in ceramics, but its applications have expanded significantly with industrial advancements. During the 20th century, the discovery of new deposits and technological improvements in mining and processing increased its commercial importance.
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