Topaz

Al₂F_1.4H_0.6O_4.6Si

Alberico, A.Ferrando, S.Ivaldi, G.Ferraris, G.

European Journal of Mineralogy (2003) 15, 875-881

a=4.6696Å   b=8.8486Å   c=8.3915Å

α=90°   β=90°   γ=90°