data_global _chemical_name_mineral 'Forsterite' loop_ _publ_author_name 'Hazen R M' _journal_name_full 'American Mineralogist' _journal_volume 61 _journal_year 1976 _journal_page_first 1280 _journal_page_last 1293 _publ_section_title ; Effects of temperature and pressure on the crystal structure of forsterite T = 23 C P = 40 kb olivine ; _database_code_amcsd 0000551 _chemical_formula_sum 'Si Mg2 O4' _cell_length_a 4.734 _cell_length_b 10.02 _cell_length_c 5.940 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 281.762 _exptl_crystal_density_diffrn 3.317 _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 _atom_site_U_iso_or_equiv Si 0.42600 0.09300 0.25000 0.00570 Mg1 0.00000 0.00000 0.00000 0.00469 Mg2 0.99100 0.28000 0.25000 0.00659 O1 0.76800 0.09700 0.25000 0.00127 O2 0.22800 0.44400 0.25000 ? O3 0.27600 0.15800 0.03500 0.00507