data_Fayalite _chemical_name_systematic 'Iron silicate - $-alpha' _chemical_name_mineral 'Fayalite' _chemical_formula_structural 'Fe2 Si O4' _chemical_formula_sum 'Fe2 O4 Si' _publ_section_title ; X-ray Determination of Electron Distributions in Forsterite, Fayalite and Tephroite ; loop_ _publ_author_name 'Fujino, K' 'Sasaki, S' 'Takeuchi, Y' 'Sadanaga, R' _journal_name_full 'Acta Crystallographica B (24,1968-38,1982)' _journal_coden_ASTM ACBCAR _journal_volume 37 _journal_year 1981 _journal_page_first 513 _journal_page_last 518 _cell_length_a 4.8195(6) _cell_length_b 10.4788(17) _cell_length_c 6.0873(8) _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 307.4 _cell_formula_units_Z 4 _symmetry_space_group_name_H-M 'P b n m' _symmetry_Int_Tables_number 62 _symmetry_cell_setting orthorhombic loop_ _symmetry_equiv_pos_as_xyz 'x,y,z' '1/2-x,1/2+y,1/2-z' '-x,-y,1/2+z' '1/2+x,1/2-y,-z' '-x,-y,-z' '1/2+x,1/2-y,1/2+z' 'x,y,1/2-z' '1/2-x,1/2+y,z' loop_ _atom_type_symbol _atom_type_oxidation_number Fe2+ 2.000 Si4+ 4.000 O2- -2.000 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_symbol _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_attached_hydrogens _atom_site_calc_flag Fe1 Fe2+ 4 a 0. 0. 0. 1. 0 d Fe2 Fe2+ 4 c 0.98598(5) 0.28026(2) 0.25 1. 0 d Si1 Si4+ 4 c 0.43122(10) 0.09765(5) 0.25 1. 0 d O1 O2- 4 c 0.76814(23) 0.09217(12) 0.25 1. 0 d O2 O2- 4 c 0.20895(25) 0.45365(11) 0.25 1. 0 d O3 O2- 8 d 0.28897(17) 0.16563(9) 0.03643(9) 1. 0 d _refine_ls_R_factor_all 0.0255