Biotite
Takeda H, Ross M
American Mineralogist 60 (1975) 1030-1040
Mica polytypism: Dissimilarities in the crystal structures of coexisting 1M and
2M1 biotite
_database_code_amcsd 0000479
5.329 9.234 20.098 90 95.09 90 C2/c
atom     x     y       z  occ B(1,1) B(2,2) B(3,3) B(1,2) B(1,3) B(2,3)
Mg1    .75   .25       0 .667  .0055  .0025  .0007      0  .0003      0
Al1    .75   .25       0 .333  .0055  .0025  .0007      0  .0003      0
Mg2  .2406 .0802 -.00004 .667  .0110  .0026  .0006  .0020  .0002  .0002
Al2  .2406 .0802 -.00004 .333  .0110  .0026  .0006  .0020  .0002  .0002
K        0 .0840     .25   .5  .0182  .0065  .0015      0  .0003      0
Si1  .4621 .2498   .1380  .75  .0052  .0023  .0005  .0003  .0001  .0001
Al3  .4621 .2498   .1380  .25  .0052  .0023  .0005  .0003  .0001  .0001
Si2  .9635 .4169   .1380  .75  .0053  .0022  .0005 -.0006  .0002 -.0002
Al4  .9635 .4169   .1380  .25  .0053  .0022  .0005 -.0006  .0002 -.0002
O1   .7410 .3140   .1662       .0136  .0054  .0008 -.0019  .0000  .0001
O2   .2430 .3532   .1672       .0108  .0060  .0008  .0025  .0000 -.0002
O3   .4337 .0840   .1666       .0181  .0038  .0007  .0003  .0004  .0000
O4   .4314 .2406   .0545       .0047  .0007  .0006  .0001  .0003  .0004
O5   .9375 .4090   .0547       .0070  .0014  .0005  .0011  .0002  .0005
O6   .9348 .0739   .0508       .0088  .0011  .0006  .0009  .0000  .0000