data_global _chemical_name_mineral 'Sillimanite' loop_ _publ_author_name 'Winter J K' 'Ghose S' _journal_name_full 'American Mineralogist' _journal_volume 64 _journal_year 1979 _journal_page_first 573 _journal_page_last 586 _publ_section_title ; Thermal expansion and high-temperature crystal chemistry of the Al2SiO5 polymorphs T = 400 deg C ; _database_code_amcsd 0000724 _chemical_formula_sum 'Al2 Si O5' _cell_length_a 7.4932 _cell_length_b 7.7035 _cell_length_c 5.7872 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 334.060 _exptl_crystal_density_diffrn 3.222 _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 Al1 0.00000 0.00000 0.00000 Al2 0.14150 0.34550 0.25000 Si 0.15280 0.34070 0.75000 O1 0.35980 0.40990 0.75000 O2 0.35670 0.43510 0.25000 O3 0.47710 0.00120 0.75000 O4 0.12490 0.22410 0.51460 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Al1 0.00683 0.01082 0.01035 -0.00029 -0.00044 -0.00023 Al2 0.00740 0.01142 0.01137 -0.00029 0.00000 0.00000 Si 0.00683 0.00962 0.01052 -0.00117 0.00000 0.00000 O1 0.00683 0.01533 0.01374 -0.00292 0.00000 0.00000 O2 0.00768 0.01593 0.01289 -0.00351 0.00000 0.00000 O3 0.01934 0.02104 0.02613 -0.01053 0.00000 0.00000 O4 0.01451 0.01172 0.01103 -0.00351 -0.00044 -0.00045