AM_Helvine Formula: Mn4 O12 Be3 Si3 S Name: Helvine Unit cell: 8.236 8.236 8.236 90.0 90.0 90.0 , V=558.66 Space group: P-43N (218)

Hassan I , Grundy H D , American Mineralogist , 70 (1985) p.186-192, The crystal structures of helvite group minerals, (MnFeZn)8(Be6Si6O24)S2