Andalusite
Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5. At higher temperatures and pressures, andalusite may convert to sillimanite. Andalusite is an index mineral: it gives clues to the depth and pressures the host rock went through in the past.
Andalusite Media
A round faceted andalusite, 4,1 millimeter in diameter, with mixed shades of brown, olive green and rusty orange. Private collection in Lysekil, Sweden.
