Boromullite

Al_4.5B_0.5O_9.5Si

Buick, I. S.Grew, E. S.Armbruster, T.Medenbach, O.Yates, M.Bebout, G.Clarke, G.

European Journal of Mineralogy (2008) 20, 935-950

a=5.7168Å   b=15.023Å   c=7.675Å

α=90°   β=90°   γ=90°