Kyanite is an aluminum silicate mineral, often occurring as long, striated bladed crystals that may be transparent or translucent with a pearly sheen. The most common colors in metaphysical use are blue streaked with white, indigo, green, and black, though Kyanite may occur in white, gray, pink, yellow, and most recently discovered orange. Kyanite comes from the Greek work, kuanos or kyanos, meaning "deep blue," and was once commonly called Disthene, which means "two strengths." It is also known as Rhaeticide and Cyanite. Its most identifiable feature is its anisotropism, the ability to cleave perfectly in two directions with two distinctly different hardnesses on the perpendicular axes. [Simmons, 223][Wikipedia.org] Kyanite is valuable in the industrial world for heat resistance, used in high refractory porcelain, refractory bricks, mortars, kiln furniture and foundry molds, in the auto and railroad industries for brake shoes, grinding wheels and cutting disks, and in the standard porcelain of dentures, sinks and bathroom fixtures. Kyanite crystals that are highly transparent and attractive in color can be cut into cabochon and faceted gemstones, and are considered to be "exotic" gems. [Geology.com]