data_global _chemical_name_mineral 'Forsterite' loop_ _publ_author_name 'Baur W H' _journal_name_full 'American Mineralogist' _journal_volume 57 _journal_year 1972 _journal_page_first 709 _journal_page_last 731 _publ_section_title ; Computer-simulated crystal structures of observed and hypothetical Mg2SiO4 polymorphs of low and high density ; _database_code_amcsd 0000276 _chemical_compound_source 'hypothetical' _chemical_formula_sum 'Si Mg2 O4' _cell_length_a 4.79 _cell_length_b 10.19 _cell_length_c 5.85 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 285.539 _exptl_crystal_density_diffrn 3.273 _symmetry_space_group_name_H-M 'P b n m' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,y,1/2-z' '-x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si 0.09450 0.40780 0.25000 Mg1 0.00000 0.00000 0.00000 Mg2 0.00560 0.26320 0.75000 O1 0.24990 0.09070 0.75000 O2 0.28320 0.05780 0.25000 O3 0.23120 0.33700 0.47070