Andalusite, kyanite, and sillimanite are naturally occurring aluminosilicate minerals that have the composition Al2SiO5. The triple point of the three polymorphs is located at a temperature of 500 °C and a pressure of 0.4 GPa. These three minerals are commonly used as index minerals in metamorphic rocks.
Hydrated aluminosilicate minerals are referred to as zeolites and are porous structures that are naturally occurring materials.
The catalyst silica-alumina is an amorphous substance which is not an aluminosilicate compound.
See also 
- Whitney, D.L. (2002), "Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey", American Mineralogist 87 (4): 405–416
- Andalusite, Handbook of Mineralogy
- Kyanite, Handbook of Mineralogy
- Sillimanite, Handbook of Mineralogy
|This article about a specific mineral or mineraloid is a stub. You can help Wikipedia by expanding it.|