Sillimanite is a mineral composed of aluminum silicate, commonly found in metamorphic rocks. It typically forms under high-temperature and high-pressure conditions, making it a key indicator of metamorphic processes. Sillimanite can appear in various colors, including brown, green, and white, and is often used in the production of ceramics and refractory materials. This mineral is part of the andalusite and kyanite group, which are all polymorphs of aluminum silicate. Sillimanite is named after the American chemist Benjamin Silliman, who contributed to the study of minerals in the 19th century. Its unique properties make it valuable in geology and industrial applications.