data_global _chemical_name_mineral 'Nacrite' loop_ _publ_author_name 'Hendricks S' _journal_name_full 'Zeitschrift fur Kristallographie' _journal_volume 100 _journal_year 1939 _journal_page_first 509 _journal_page_last 518 _publ_section_title ; The Crystal Structure of Nacrite Al2 O3 * 2Si O2 * 2H2 O and the Polymorphism of the Kaolin Minerals. _cod_database_code 1011062 ; _database_code_amcsd 0017961 _chemical_formula_sum 'Al2 Si2 O9' _cell_length_a 8.94 _cell_length_b 5.14 _cell_length_c 43.0 _cell_angle_alpha 90 _cell_angle_beta 90.33 _cell_angle_gamma 90 _cell_volume 1975.886 _exptl_crystal_density_diffrn 2.563 _symmetry_space_group_name_H-M 'C 1 c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Al1 0.83330 0.16670 0.06400 Al2 0.16670 0.16670 0.06400 Al3 0.50000 0.16670 0.73070 Al4 0.83330 0.16670 0.73070 Al5 0.16670 0.16670 0.39730 Al6 0.50000 0.16670 0.39730 Si1 0.00000 0.00000 0.66670 Si2 0.66670 0.00000 0.33330 Si3 0.33330 0.00000 0.00000 Si4 0.00000 0.00000 0.33330 Si5 0.66670 0.00000 0.00000 Si6 0.33330 0.00000 0.66670 O1 0.00000 0.00000 0.70300 O2 0.66670 0.00000 0.37000 O3 0.33330 0.00000 0.03600 O4 0.00000 0.00000 0.37000 O5 0.66670 0.00000 0.03700 O6 0.33330 0.00000 0.70300 O7 0.00000 0.00000 0.03700 O8 0.66670 0.00000 0.70400 O9 0.33330 0.00000 0.37000 O10 0.25000 0.25000 -0.01200 O11 0.91700 0.25000 0.65500 O12 0.58300 0.25000 0.32100 O13 0.00000 0.50000 -0.01200 O14 0.66670 0.50000 0.65500 O15 0.33330 0.50000 0.32100 O16 0.75000 0.25000 -0.01200 O17 0.41700 0.25000 0.65500 O18 0.08300 0.25000 0.32100 O19 0.66650 0.33350 0.08600 O20 0.33320 0.33350 0.75270 O21 -0.00020 0.33350 0.41930 O22 0.00000 0.33300 0.08600 O23 0.66670 0.33300 0.41930 O24 0.33330 0.33300 0.75270 O25 0.33350 0.33350 0.08600 O26 0.66680 0.33350 0.41930 O27 0.00020 0.33350 0.75270