data_global _chemical_name_mineral 'Mullite' loop_ _publ_author_name 'Balzar D' 'Ledbetter H' _journal_name_full 'American Mineralogist' _journal_volume 78 _journal_year 1993 _journal_page_first 1192 _journal_page_last 1196 _publ_section_title ; Crystal structure and compressibility of 3:2 mullite ; _database_code_amcsd 0001618 _chemical_formula_sum 'Al2.25 Si.75 O4.871' _cell_length_a 7.54336 _cell_length_b 7.69176 _cell_length_c 2.88402 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 167.336 _exptl_crystal_density_diffrn 3.170 _symmetry_space_group_name_H-M 'P b a m' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2-y,z' '1/2-x,1/2+y,-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' 'x,y,-z' '-x,-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 Al 0.00000 0.00000 0.00000 1.00000 0.00291 Al1 0.14850 0.34070 0.50000 0.52500 0.00304 Si1 0.14850 0.34070 0.50000 0.34200 0.00304 Al2 0.26100 0.20730 0.50000 0.10000 ? Si2 0.26100 0.20730 0.50000 0.03300 ? O1 0.35770 0.42350 0.50000 1.00000 0.02685 O2 0.50000 0.00000 0.50000 0.47500 0.02609 O3 0.46350 0.04650 0.50000 0.19800 0.05737 O4 0.12650 0.21970 0.00000 1.00000 0.02736