Kyanite

An unusal gem that has rich intense blue hues resembling sapphire although Kyanite will appear more steely and silky. It grows in metamorphic rocks and responds to stress, so you can actually tell which direction the earth was pressing on the Kyanite by which direction the crystals grew ,which in turn can tell you a lot about the movement of earth overtime where they grew

One of the strangest qualities of Kyanite is that it has anisotropic hardness, simply put it has two different harnesses depending on what angle you scratch it. Depending on how you’re holding it, if you scratch it vertically it can be a 4 – 4.5 hardness and if you scratch horizontally it can be a 6 – 7 hardness because its atomic structure is strongly connected in one direction, like axing a tree in its side versus from the top to split it. They are stunning gems and make for great conversation pieces in jewelry

Hardness: 4 – 4.5 or 6 – 7
Composition: Al₂SiO₅