Grumantite

H₃NaO₆Si₂

Yamnova, N. Y.Pushcharovsky, D. Y.Andrianov, V. I.Rastsvetaeva, R. K.Khomyakov, A. P.Mikheeva, M. G.

Soviet Physics Doklady (1989) 34, 284-286

a=15.979Å   b=18.25Å   c=7.169Å

α=90°   β=90°   γ=90°