
A unique variety of andalusite is called "chiastolite".
It contains black or brown clay and/or carbonaceous material
inclusioned in the crystal and arranged in regular symmetrical
shapes. Andalusite is also pleochroic i.e. different colors in
different directions. The best color play of andalusite is seen in
fancy shapes, particularly rectangular cushion shapes: in round
cuts, the colors blend together.
Andalusite is mined in Brazil and Sri Lanka. Owing to its color and
durability, andalusite is appropriate for men's jewelry.