A specimen of andalusite from Tyrol, Austria.
Andalusite is usually pink but white, gray, yellow, green, and violet varieties also occur frequently. It crystallizes in the orthorhombic system. Hardness: 7.5.
Chiastolite is a variety of andalusite, aluminate silicate (Al2OSiO4), found in metamorphic rocks. It has elongated prismatic crystals, which in cross-section show a black cross on a gray ground. Hardness 7.5; relative density 3.1–3.2.