Werdingite

Al_6.25B_2.54Fe_0.37Mg_0.84O_18.5Si₂

Niven, M. L.Waters, D. J.Moore, J. M.

American Mineralogist (1991) 76, 246-256

a=7.995Å   b=8.152Å   c=11.406Å

α=110.45°   β=110.85°   γ=84.66°