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 0000862
_chemical_formula_sum 'Mg1.638 Fe.864 Al1.322 Ti.336 Si2.84 K O12'
_cell_length_a 5.3175
_cell_length_b 9.212
_cell_length_c 19.976
_cell_angle_alpha 90
_cell_angle_beta 95.09
_cell_angle_gamma 90
_cell_volume 974.662
_exptl_crystal_density_diffrn      3.071
_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   0.75000   0.25000   0.00000   0.61200
Fe1   0.75000   0.25000   0.00000   0.20000
Al1   0.75000   0.25000   0.00000   0.18800
Mg2   0.23210   0.07750  -0.00001   0.51300
Fe2   0.23210   0.07750  -0.00001   0.29600
Ti2   0.23210   0.07750  -0.00001   0.16800
Al2   0.23210   0.07750  -0.00001   0.02300
Si1   0.46240   0.24902   0.13850   0.71200
Al1   0.46240   0.24902   0.13850   0.28000
Fe1   0.46240   0.24902   0.13850   0.00800
Si2   0.96450   0.41630   0.13857   0.70800
Al2   0.96450   0.41630   0.13857   0.26400
Fe2   0.96450   0.41630   0.13857   0.02800
K   0.00000   0.08320   0.25000   1.00000
O11   0.74210   0.31390   0.16640   1.00000
O21   0.24160   0.35120   0.16770   1.00000
O22   0.43520   0.08220   0.16750   1.00000
O31   0.43090   0.24770   0.05473   1.00000
O32   0.93920   0.41720   0.05466   1.00000
O4   0.93330   0.08270   0.04994   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 0.00725 0.00645 0.01424 0.00000 0.00075 0.00000
Fe1 0.00725 0.00645 0.01424 0.00000 0.00075 0.00000
Al1 0.00725 0.00645 0.01424 0.00000 0.00075 0.00000
Mg2 0.01094 0.00800 0.01364 0.00395 0.00000 0.00084
Fe2 0.01094 0.00800 0.01364 0.00395 0.00000 0.00084
Ti2 0.01094 0.00800 0.01364 0.00395 0.00000 0.00084
Al2 0.01094 0.00800 0.01364 0.00395 0.00000 0.00084
Si1 0.00654 0.00645 0.01304 0.00074 0.00037 0.00000
Al1 0.00654 0.00645 0.01304 0.00074 0.00037 0.00000
Fe1 0.00654 0.00645 0.01304 0.00074 0.00037 0.00000
Si2 0.00696 0.00731 0.01264 0.00074 0.00016 0.00037
Al2 0.00696 0.00731 0.01264 0.00074 0.00016 0.00037
Fe2 0.00696 0.00731 0.01264 0.00074 0.00016 0.00037
K 0.02331 0.02407 0.03570 0.00000 0.00230 0.00000
O11 0.01450 0.02021 0.01785 -0.00395 0.00053 0.00139
O21 0.01464 0.01935 0.01765 0.00593 -0.00053 -0.00297
O22 0.02317 0.01204 0.01705 -0.00025 0.00427 0.00000
O31 0.00767 0.00731 0.01284 0.00272 0.00053 -0.00093
O32 0.00753 0.00774 0.01203 0.00346 0.00000 -0.00093
O4 0.01009 0.00989 0.01324 0.00494 0.00000 -0.00279