Andalusite

Andalusite is a silicate with composition Al₂SiO₅ . This sample is about 7x7 cm. The chemical compostion is the same as the minerals sillimanite and kyanite. These samples are on display at the Smithsonian Museum of Natural History.

These gems are 28.3 and 30.5 carats and are from Minas Gerais, Brazil.

This sample is about 7x5 cm and is from Harding pegmatite, Dixon, New Mexico.