data_global _chemical_name_mineral 'Hydroxylapatite' loop_ _publ_author_name 'Wilson R M' 'Elliot J C' 'Dowker S E P' _journal_name_full 'American Mineralogist' _journal_volume 84 _journal_year 1999 _journal_page_first 1406 _journal_page_last 1414 _publ_section_title ; Rietveld refinement of the crystallographic structure of human dental enamel apatites Sample: RC7 - enamel ; _database_code_amcsd 0002286 _chemical_formula_sum 'Ca4.73 Na.1 Mg.05 P2.79 O11.99 H2' _cell_length_a 9.4512 _cell_length_b 9.4512 _cell_length_c 6.8803 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 532.245 _exptl_crystal_density_diffrn 2.954 _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 Ca1 0.66667 0.33333 0.00420 0.97000 Na1 0.66667 0.33333 0.00420 0.02000 Mg1 0.66667 0.33333 0.00420 0.01000 Ca2 0.24570 0.98960 0.25000 0.93000 Na2 0.24570 0.98960 0.25000 0.02000 Mg2 0.24570 0.98960 0.25000 0.01000 P 0.39820 0.36860 0.25000 0.93000 O1 0.32830 0.48590 0.25000 0.89000 O2 0.57540 0.45510 0.25000 1.00000 O3 0.33590 0.25260 0.06990 0.88000 O-h 0.00000 0.00000 0.18810 0.52000 H 0.00000 0.00000 0.06080 1.00000