data_global _chemical_name_mineral 'Biotite' loop_ _publ_author_name 'Takeda H' 'Ross M' _journal_name_full 'American Mineralogist' _journal_volume 60 _journal_year 1975 _journal_page_first 1030 _journal_page_last 1040 _publ_section_title ; Mica polytypism: Dissimilarities in the crystal structures of coexisting 1M and 2M1 biotite ; _database_code_amcsd 479 _chemical_formula_sum 'Mg2.001 Al1.999 K.5 Si3 O12' _cell_length_a 5.329 _cell_length_b 9.234 _cell_length_c 20.098 _cell_angle_alpha 90.0 _cell_angle_beta 95.09 _cell_angle_gamma 90.0 _cell_volume 985.082 _exptl_crystal_density_diffrn 2.686 _symmetry_space_group_name_H-M 'C 1 2/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' '-x,y,1/2-z' '1/2-x,1/2+y,1/2-z' '-x,-y,-z' '1/2-x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy Mg1 0.75 0.25 0.0 0.667 Al1 0.75 0.25 0.0 0.333 Mg2 0.2406 0.0802 -4e-05 0.667 Al2 0.2406 0.0802 -4e-05 0.333 K 0.0 0.084 0.25 0.5 Si1 0.4621 0.2498 0.138 0.75 Al3 0.4621 0.2498 0.138 0.25 Si2 0.9635 0.4169 0.138 0.75 Al4 0.9635 0.4169 0.138 0.25 O1 0.741 0.314 0.1662 1.0 O2 0.243 0.3532 0.1672 1.0 O3 0.4337 0.084 0.1666 1.0 O4 0.4314 0.2406 0.0545 1.0 O5 0.9375 0.409 0.0547 1.0 O6 0.9348 0.0739 0.0508 1.0 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 Mg1 0.00785 0.0108 0.01421 0.0 0.00161 0.0 Al1 0.00785 0.0108 0.01421 0.0 0.00161 0.0 Mg2 0.0157 0.01123 0.01218 0.00497 0.00108 0.00187 Al2 0.0157 0.01123 0.01218 0.00497 0.00108 0.00187 K 0.02598 0.02808 0.03045 0.0 0.00161 0.0 Si1 0.00742 0.00994 0.01015 0.00074 0.00054 0.00094 Al3 0.00742 0.00994 0.01015 0.00074 0.00054 0.00094 Si2 0.00756 0.0095 0.01015 -0.00149 0.00108 -0.00187 Al4 0.00756 0.0095 0.01015 -0.00149 0.00108 -0.00187 O1 0.01941 0.02333 0.01624 -0.00472 0.0 0.00094 O2 0.01542 0.02592 0.01624 0.00621 0.0 -0.00187 O3 0.02583 0.01641 0.01421 0.00074 0.00215 0.0 O4 0.00671 0.00302 0.01218 0.00025 0.00161 0.00375 O5 0.00999 0.00605 0.01015 0.00273 0.00108 0.00468 O6 0.01256 0.00475 0.01218 0.00223 0.0 0.0