data_global _chemical_name_mineral 'Hydroxylapatite' loop_ _publ_author_name 'Hughes J M' 'Cameron M' 'Mariano A N' _journal_name_full 'American Mineralogist' _journal_volume 76 _journal_year 1991 _journal_page_first 1165 _journal_page_last 1173 _publ_section_title ; Rare-earth-element ordering and structural variations in natural rare-earth-bearing apatites sample B from the Oka carbonatite ; _database_code_amcsd 0001375 _chemical_formula_sum 'Ca4.557 Na.02 Ce.423 (P2.595 Si.405) O12.664 F.335 H.664' _cell_length_a 9.4202 _cell_length_b 9.4202 _cell_length_c 6.9157 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 531.480 _exptl_crystal_density_diffrn 3.398 _symmetry_space_group_name_H-M 'P 63/m' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x+y,-x,1/2-z' 'x-y,x,1/2+z' 'y,-x+y,-z' '-y,x-y,z' 'x,y,1/2-z' '-x,-y,1/2+z' 'x-y,x,-z' '-x+y,-x,z' '-y,x-y,1/2-z' 'y,-x+y,1/2+z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Ca1 0.66667 0.33333 0.00040 0.93900 0.01394 Na1 0.66667 0.33333 0.00040 0.01000 0.01394 Ce1 0.66667 0.33333 0.00040 0.05100 0.01394 Ca2 0.99088 0.24301 0.25000 0.89300 0.01267 Ce2 0.99088 0.24301 0.25000 0.10700 0.01267 P 0.36896 0.39824 0.25000 0.86500 0.00925 Si 0.36896 0.39824 0.25000 0.13500 0.00925 O1 0.48420 0.32610 0.25000 1.00000 0.01368 O2 0.46590 0.58740 0.25000 1.00000 0.01710 O3 0.25670 0.34210 0.07080 1.00000 0.02178 F 0.00000 0.00000 0.25000 0.33500 0.02406 O-H 0.00000 0.00000 0.30400 0.33200 0.02913