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 478 _chemical_formula_sum 'Mg2.001 Al1.999 K Si3 O12 H2' _cell_length_a 5.331 _cell_length_b 9.231 _cell_length_c 10.173 _cell_angle_alpha 90.0 _cell_angle_beta 100.16 _cell_angle_gamma 90.0 _cell_volume 492.768 _exptl_crystal_density_diffrn 2.83 _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 0.0 0.0 0.5 0.667 Mg2 0.0 0.3392 0.5 0.667 Al1 0.0 0.0 0.5 0.333 Al2 0.0 0.3392 0.5 0.333 K1 0.0 0.5 0.0 1.0 Si1 0.0745 0.1671 0.2242 0.75 Al3 0.0745 0.1671 0.2242 0.25 O1 0.0165 0.0 0.1674 1.0 O2 0.324 0.231 0.166 1.0 O3 0.131 0.1684 0.3906 1.0 O-H4 0.1312 0.5 0.3985 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 0.01186 0.0082 0.0254 0.0 0.00612 0.0 Mg2 0.00893 0.01425 0.02083 0.0 0.00319 0.0 Al1 0.01186 0.0082 0.0254 0.0 0.00612 0.0 Al2 0.00893 0.01425 0.02083 0.0 0.00319 0.0 K1 0.02511 0.02288 0.04013 0.0 0.00745 0.0 Si1 0.00767 0.00548 0.0157 0.0 0.00346 0.0 Al3 0.00767 0.00548 0.0157 0.0 0.00346 0.0 O1 0.02399 0.01036 0.02083 0.0 0.00346 0.0 O2 0.01604 0.01899 0.0254 -0.00417 0.00453 -0.00281 O3 0.01032 0.00777 0.01676 0.00074 0.00399 0.0 O-H4 0.01102 0.01209 0.01575 0.0 0.00213 0.0