It soon became clear that it was a locality error, and that the specimens studied were actually from El Cardoso de la Sierra, in the Spanish province of Guadalajara, not Andalusia.

Thus, as with its other polymorphs, andalusite is an aluminosilicate index mineral, providing clues to depth and pressures involved in producing the host rock.

[5] The variety chiastolite commonly contains dark inclusions of carbon or clay which form a cruciform pattern when shown in cross-section.

The minerals kyanite and sillimanite are polymorphs of andalusite, each occurring under different temperature-pressure regimes and are therefore rarely found together in the same rock.

[13] The world's highest concentration of andalusite is found in the Glomel mine in Côtes-d'Armor (France) which accounts for 25% of the global production of this mineral.