The authors present here the superior result of synchrotron X-ray diffraction indexing of the 8 × 8 × 8 fluorite supercell, murataite, M8 (formula Ca66.37Mn29.33Ti186.76Zr83.35Al46.30Fe74.09O817, a = 39.277(3) Å, Z = 4). The authors present evidence that Fd$\bar 3$m (227) is the most likely space group.