Kyanite is a naturally occurring aluminum silicate mineral that's commonly blue or green in color, but can also be white, yellow, or orange. It's found in metamorphic rocks and sedimentary rock, and is often used as an industrial raw material or cut into a gemstone.

Kyanite is a key component in the production of mullite, which is used in spark plugs and other refractory porcelains. It's also used in the production of heat and acid refractories for ceramics, precision castings, and more.

Transparent, deep blue kyanite is a sought-after gemstone that's similar in color to sapphire. It can be cut into cabochons, beads, or faceted, but its color zoning and variability in hardness can make it difficult to work with.