A variety of andalusite; -- called also macle. The tessellated appearance of a cross section is due to the symmetrical arrangement of impurities in the crystal.

The variety of andalusite with a diagnostic cross pattern of minute dark inclusions when viewed on end.

The mineral chiastolite is a variety of andalusite with the chemical composition Al2SiO5. It is noted for distinctive cross-shaped black inclusions of graphite. in the area around Georgetown, California metamorphosed sediments contained andalusite and chiastolite in a graphite rich metasediment. The chiastolite crystals have been pseudomorphically altered by a mixture of muscovite, paragonite and margarite.