Mullite
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Description
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 |
| Density | 3.15 g/ml |
| Refractive Index | 1.642 -1.679 |
Resources and Citations
- R. Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Co., Radnor, PA, 1996.