Kyanite often occurs as long, bladed, striated crystals, transparent or translucent with a pearly luster. An aluminum silicate mineral, it may appear in white, pink, yellow, orange, green, blue, gray and black. In addition to its value as a gemstone, Kyanite is also extremely useful in industrial applications due to its high heat resistance. It is often used in kiln furniture and foundry molds, as well as for brake shoes, grinding wheels and cutting disks, and in standard porcelain.