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