AM_Omphacite_1 Formula: Si4 Al.868 Fe.317 Mg.815 (Ca1.03 Na.97) O12 Name: Omphacite Unit cell: 9.585 8.776 5.26 90.0 106.8 90.0 , V=423.58 Space group: P12/N1 (13)

Matsumoto T , Tokonami M , Morimoto N , American Mineralogist , 60 (1975) p.634-641, The crystal structure of omphacite