Itinga, Minas Gerais, Brazil

Al₂SiO₄O

Crystal System: orthorhombic
Colour: pink to red brown, occasionally yellow, green, white, gray, rarely violet
Lustre: vitreous, sub-vitreous, greasy
Habitus: prismatic
Hardness: 6½ - 7½
Fracture: irregular/uneven, sub-conchoidal
Cleavage:  good on {110} - poor on {100}
Density: 3.149 g/cm³ 
Origin and geological occurrence: andalusite is the result of contact metamorphism of argillaceous sediments; also in regionally metamorphosed schists. Rarely found in granites and pegmatites. It is a polymorph of Al₂SiO₄O.

Samples:

9A.7 Andalusite Pinkish prismatic crystals with mica and quartz. Villa di Chiavenna, Sondrio, Lombardy, Italy. #neso soro silicates