Biotite
Ohta T, Takeda H, Takeuchi Y
American Mineralogist 67 (1982) 298-310
Mica polytypism: Similarities in the crystal structures of coexisting 1M and
2M(1) oxybiotite
Sample: in the 2M1 setting
_database_code_amcsd 0000863
5.3183 9.211 10.105 90 100.09 90 C2/m
atom      x       y      z  occ
Mg1 -.00005 -.00005  .5000 .612
Fe1 -.00005 -.00005  .5000 .200
Al1 -.00005 -.00005  .5000 .188
Mg2   .0001  .34513  .5000 .513
Fe2   .0001  .34513  .5000 .296
Ti2   .0001  .34513  .5000 .168
Al2   .0001  .34513  .5000 .023
Si1   .0732  .16733 .22299 .356
Al1   .0732  .16733 .22299 .140
Fe1   .0732  .16733 .22299 .004
Si2   .0731  .16734 .22286 .354
Al2   .0731  .16734 .22286 .132
Fe2   .0731  .16734 .22286 .014
K         0      .5      0
O11   .0167   .0003  .1671
O21   .3223   .2315  .1647
O22   .3221   .2309  .1651
O31   .1287   .1698  .3905
O32   .1288   .1691  .3907
O4    .1324   .4998  .4001