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Ca 2 Ln 8 (SiO 4 ) 6 O 2 apatites with Ln = La, Ce, Pr, Nd, Sm, Eu, Gd and Tb crystallize in space group P 6 3 / m . The crystal structure of apatite-type Ca 2 Ce 8 (SiO 4 ) 6 O 2 [dicalcium octa-cerium hexa-kis-(silicate) dioxide], which has been synthesized by calcination, was refined from powder X-ray diffraction data using the Rietveld method. A database survey shows that contrary to the previously published Ca 2 Ce 8 (SiO 4 ) 6 O 2 structure [Skakle et al. (2000 ▸). Powder Diffr. 15 , 234-238], the cell volume of the structure reported here is consistent with those of other Ln apatites.