data_global _chemical_name_mineral 'Biotite' loop_ _publ_author_name 'Ohta T' 'Takeda H' 'Takeuchi Y' _journal_name_full 'American Mineralogist' _journal_volume 67 _journal_year 1982 _journal_page_first 298 _journal_page_last 310 _publ_section_title ; Mica polytypism: Similarities in the crystal structures of coexisting 1M and 2M(1) oxybiotite ; _database_code_amcsd 0000861 _chemical_formula_sum 'Mg1.638 Fe.864 Al1.322 Ti.336 Si2.84 K O12' _cell_length_a 5.3204 _cell_length_b 9.210 _cell_length_c 10.104 _cell_angle_alpha 90 _cell_angle_beta 100.102 _cell_angle_gamma 90 _cell_volume 487.429 _exptl_crystal_density_diffrn 3.071 _symmetry_space_group_name_H-M 'C 1 2/m 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,z' '1/2+x,1/2-y,z' '-x,y,-z' '1/2-x,1/2+y,-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 0.00000 0.00000 0.50000 0.62400 Fe1 0.00000 0.00000 0.50000 0.19000 Al1 0.00000 0.00000 0.50000 0.18600 Mg2 0.00000 0.34538 0.50000 0.50700 Fe2 0.00000 0.34538 0.50000 0.28900 Ti2 0.00000 0.34538 0.50000 0.16800 Al2 0.00000 0.34538 0.50000 0.03600 Si 0.07300 0.16733 0.22283 0.71000 Al 0.07300 0.16733 0.22283 0.26600 Fe 0.07300 0.16733 0.22283 0.02400 K 0.00000 0.50000 0.00000 1.00000 O1 0.01770 0.00000 0.16660 1.00000 O2 0.32170 0.23150 0.16450 1.00000 O3 0.12980 0.16970 0.39050 1.00000 O4 0.13350 0.50000 0.40060 1.00000 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 0.00556 0.00516 0.01654 0.00000 0.00317 0.00000 Fe1 0.00556 0.00516 0.01654 0.00000 0.00317 0.00000 Al1 0.00556 0.00516 0.01654 0.00000 0.00317 0.00000 Mg2 0.00459 0.01229 0.01544 0.00000 0.00193 0.00000 Fe2 0.00459 0.01229 0.01544 0.00000 0.00193 0.00000 Ti2 0.00459 0.01229 0.01544 0.00000 0.00193 0.00000 Al2 0.00459 0.01229 0.01544 0.00000 0.00193 0.00000 Si 0.00625 0.00679 0.01569 0.00010 0.00230 0.00005 Al 0.00625 0.00679 0.01569 0.00010 0.00230 0.00005 Fe 0.00625 0.00679 0.01569 0.00010 0.00230 0.00005 K 0.02321 0.02278 0.03760 0.00000 0.00607 0.00000 O1 0.02029 0.01117 0.02055 0.00000 0.00158 0.00000 O2 0.01362 0.01891 0.02005 -0.00464 0.00449 -0.00232 O3 0.00681 0.00645 0.01554 0.00024 0.00290 -0.00046 O4 0.00792 0.00945 0.01504 0.00000 0.00264 0.00000