Kyanite is an aluminum silicate mineral which is very difficult to facet due to its perfect cleavage and variable hardness within a same crystal. It is the only stone which if cut parallel to its c-axis then the hardness is around 4 to 4.5 and if cut perpendicular to c-axis then the hardness is 6 to 7.5. Kyanite occurs in various colors like blue, teal, green, and orange.
Moh Hardness- 4-7
Origin- Nepal, India, Madagascar and Namibia.
