AM_Harrisonite Formula: Ca (Fe5.28 Mg.72) Si2 P2 O16 Name: Harrisonite Unit cell: 6.248 6.248 26.802 90.0 90.0 120.0 , V=906.11 Space group: R-3M (166)

Grice J D , Roberts A C , The Canadian Mineralogist , 31 (1993) p.781-785, Harrisonite, a well-ordered silico-phosphate with a layered crystal structure., Ca(Fe,Mg)6(SiO4)2(PO4)2, Locality: Arcedeckne Island, Artic Canada