Andalusite is a mineral that is commonly found in metamorphic rocks. Also known as "chiastolite," it is usually brown or green, but can also appear in shades of white, gray, and pink. Other synonyms for andalusite include "cross-stone," "crucifix-stone," and "fairy-cakes." Andalusite is valued for its high refractive index, which makes it useful for abrasive applications in the manufacturing industry. It is also sometimes used as a gemstone, although it is not as well-known as other minerals such as diamond or ruby. Despite its relative obscurity, andalusite remains an important mineral due to its unique properties and uses.