Grandidierite

Al₃BFe_0.1Mg_0.9O₉Si

Stephenson, D. A.Moore, P. B.

Acta Crystallographica, Section B (1968) 24, 1518-1522

a=10.335Å   b=10.978Å   c=5.760Å

α=90°   β=90°   γ=90°