AM_Grumantite Formula: Na Si2 O6 H3 Name: Grumantite Unit cell: 15.979 18.25 7.169 90.0 90.0 90.0 , V=2090.60 Space group: FDD2 (43)

Yamnova N Y , Pushcharovsky D Y , Andrianov V I , Rastsvetaeva R K , Khomyakov A P , Mikheeva M G , Soviet Physics Doklady , 34 (1989) p.284-286, A new type of silicon-oxygen group in the structure of grumantite, Na[Si2O4(OH)]*H2O, Locality: Lovozero massif, Kola Peninsula, Russia