data_global _chemical_name_mineral 'Forsterite' loop_ _publ_author_name 'Henderson C M B' 'Redfern S A T' 'Smith R I' 'Knight K S' 'Charnock J M' _journal_name_full 'American Mineralogist' _journal_volume 86 _journal_year 2001 _journal_page_first 1170 _journal_page_last 1187 _publ_section_title ; Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: A time-of-flight neutron powder diffraction and EXAFS study Sample: Mg80Ni20 at T = 700 C ; _database_code_amcsd 0002713 _chemical_formula_sum '(Ni.4 Mg1.6) Si O4' _cell_length_a 4.77799 _cell_length_b 10.2928 _cell_length_c 6.01488 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 295.805 _exptl_crystal_density_diffrn 3.468 _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_occupancy _atom_site_U_iso_or_equiv Ni1 0.00000 0.00000 0.00000 0.35800 0.01267 Mg1 0.00000 0.00000 0.00000 0.64200 0.01267 Ni2 0.98940 0.27840 0.25000 0.04200 0.01418 Mg2 0.98940 0.27840 0.25000 0.95800 0.01418 Si 0.42520 0.09290 0.25000 1.00000 0.00836 O1 0.76510 0.09260 0.25000 1.00000 0.01317 O2 0.22260 0.44850 0.25000 1.00000 0.01317 O3 0.27700 0.16230 0.03380 1.00000 0.01330