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.)
Insoluble in water.
Orthorhombic system with needle-shaped crystals. Good cleavage in one direction
|Composition||3Al2O3 - 2SiO2|
|Refractive Index||1.642 -1.679|
R. Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Co., Radnor, PA, 1996.