a very hard, orthorhombic silicate of aluminum, AlSiO, usually found in schist, slate, or other metamorphic rocks and used to make various high-temperature materials and as a gem
Origin:
after Andalusia, where it was discovered
See andalusite in American Heritage Dictionary 4
noun
A mineral, aluminum silicate (Al2SiO5), usually found in orthorhombic crystals of various colors.