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
 Sample: in the 2M1 setting
;
_database_code_amcsd 0000863
_chemical_formula_sum 'Mg7.164 Fe3.512 Al3.3 Ti1.344 Si5.68 K2 O48'
_cell_length_a 5.3183
_cell_length_b 9.211
_cell_length_c 10.105
_cell_angle_alpha 90
_cell_angle_beta 100.09
_cell_angle_gamma 90
_cell_volume 487.356
_exptl_crystal_density_diffrn      5.211
_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  -0.00005  -0.00005   0.50000   0.61200
Fe1  -0.00005  -0.00005   0.50000   0.20000
Al1  -0.00005  -0.00005   0.50000   0.18800
Mg2   0.00010   0.34513   0.50000   0.51300
Fe2   0.00010   0.34513   0.50000   0.29600
Ti2   0.00010   0.34513   0.50000   0.16800
Al2   0.00010   0.34513   0.50000   0.02300
Si1   0.07320   0.16733   0.22299   0.35600
Al1   0.07320   0.16733   0.22299   0.14000
Fe1   0.07320   0.16733   0.22299   0.00400
Si2   0.07310   0.16734   0.22286   0.35400
Al2   0.07310   0.16734   0.22286   0.13200
Fe2   0.07310   0.16734   0.22286   0.01400
K   0.00000   0.50000   0.00000   1.00000
O11   0.01670   0.00030   0.16710   1.00000
O21   0.32230   0.23150   0.16470   1.00000
O22   0.32210   0.23090   0.16510   1.00000
O31   0.12870   0.16980   0.39050   1.00000
O32   0.12880   0.16910   0.39070   1.00000
O4   0.13240   0.49980   0.40010   1.00000