Kyanite | GRHardnessTester.comKyanite can be recognized by its beautiful bluish greenish coloring.  It is found most frequently in metamorphic rocks.  What is interesting about kyanite is that is has a variable hardness.  Kyanite’s crystals have a hardness of between 4.5 to 5 on Mohs hardnss scale when tested parallel to the length of the crystal.  When tested across the short dimension of the crystal, kyranite’s hardness is between 6.5 to 7.