AM_Ca4(PO4)2O Formula: Ca4 P2 O9 Name: Ca4(PO4)2O Unit cell: 7.023 11.986 9.473 90.0 90.9 90.0 , V=797.32 Space group: P1211 (4)

Dickens B , Brown W E , Kruger G J , Stewart J M , Acta Crystallographica, Section B , 29 (1973) p.2046-2056, Ca4(PO4)2O, tetracalcium diphosphate monooxide., Crystal structure and relationships to Ca5(PO4)3OH and K3Na(SO4)2, Note: z(O11) corrected to match reported bond lengths