A stable crystalline form of Aluminum silicate. Mullite is formed by heating aluminum silicate compounds, such as cyanite, Sillimanite and Andalusite, to high temperatures. It begins forming at 1000 C and the conversion is nearly complete by 1340 C. Mullite has needle-shaped crystals which provide a felting effect for strengthening stoneware and porcelain (Fournier 1996).
Synonyms and Related Terms
none; Mullit (Deut.); mulliet (Ned.)
Physical and Chemical Properties
- Insoluble in water.
- Orthorhombic system with needle-shaped crystals.
- Good cleavage in one direction
|Composition||3Al2O3 - 2SiO2|
|Melting Point||1810 C|
|Refractive Index||1.642 -1.679|
Resources and Citations
- R. Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Co., Radnor, PA, 1996.