Habit: prismatic.
Color: white.
Luster: vitreous.
Diaphaneity: transparent to translucent.
Fracture: even.
Cleavage: (010) good, (100) poor.
Twinning: {110}, {130}.
Occurrence: alumina-rich metamorphic rocks.
Cordierite is most widely used in extruded formfor insulators in such parts as heating elementsand thermocouples. It has low thermal expansion,excellent resistance to thermal shock, andgood dielectric strength.
