data_global _chemical_name_mineral 'Okayamalite' loop_ _publ_author_name 'Giuli G' 'Bindi L' 'Bonazzi P' _journal_name_full 'American Mineralogist' _journal_volume 85 _journal_year 2000 _journal_page_first 1512 _journal_page_last 1515 _publ_section_title ; Rietveld refinement of okayamalite, Ca2SiB2O7: Structural evidence for the B/Si ordered distribution ; _database_code_amcsd 0002589 _chemical_formula_sum 'Ca2 Si B2 O7' _cell_length_a 7.1248 _cell_length_b 7.1248 _cell_length_c 4.8177 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 244.560 _exptl_crystal_density_diffrn 3.284 _symmetry_space_group_name_H-M 'P -4 21 m' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2-y,1/2-x,z' 'y,-x,-z' '1/2-x,1/2+y,-z' '-x,-y,z' '1/2+y,1/2+x,z' '-y,x,-z' '1/2+x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Ca 0.33840 0.16160 0.50800 0.02000 SiT1 0.00000 0.00000 0.00000 0.01900 BT2 0.14080 0.35920 0.94700 0.01300 O1 0.50000 0.00000 0.14600 0.01300 O2 0.14240 0.35760 0.25170 0.01300 O3 0.07820 0.17770 0.81050 0.01300