Kyanite is an aluminosilicate mineral. It has needle-like crystals with unique properties making it a valuable raw material in refractories, ceramics and other products.  

Kyanite undergoes an irreversible expansion of approx. 10% when heated up to approx. 1,250°C, which is used by refractory and ceramic manufacturers to reduce shrinkage during initial firing. This makes it possible to produce nearly net shaped green bodies and avoids the forming of shrinkage cracks in the ceramic part. 

In friction materials this expansion can compensate fading. The needle-like crystals lend cold "green" strength and abrasion resistance to the end product. 

The hardness in Mohs is 4 in length and 7 in cross direction.