Sillimanite- High temperature Low pressure aluminosilicate
Andalusite- Low temperature Low pressure aluminosilicate
Kyanite- Low temperature High pressure aluminosilicate
See th...
Al2SiO5 - has three polymorphs. The high pressure form is kyanite (Triclinic), the high temperature form is sillimanite (orthorhombic), and the low temperature, low pressure form...