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 0000478
5.331 9.231 10.173 90 100.16 90 C2/m
atom     x     y     z  occ B(1,1) B(2,2) B(3,3) B(1,2) B(1,3) B(2,3)
Mg1      0     0    .5 .667  .0085  .0019  .0050      0  .0023      0
Mg2      0 .3392    .5 .667  .0064  .0033  .0041      0  .0012      0
Al1      0     0    .5 .333  .0085  .0019  .0050      0  .0023      0
Al2      0 .3392    .5 .333  .0064  .0033  .0041      0  .0012      0
K1       0    .5     0       .0180  .0053  .0079      0  .0028      0
Si1  .0745 .1671 .2242 .750  .0055 .00127 .00309  .0000  .0013 -.0000
Al3  .0745 .1671 .2242  .25  .0055 .00127 .00309  .0000  .0013 -.0000
O1   .0165     0 .1674       .0172  .0024  .0041      0  .0013      0
O2   .3240 .2310 .1660       .0115  .0044  .0050 -.0017  .0017 -.0006
O3   .1310 .1684 .3906       .0074  .0018  .0033  .0003  .0015  .0000
OH4  .1312    .5 .3985       .0079  .0028  .0031      0  .0008      0