AM_Biotite_6 Formula: Mg7.164 Fe3.512 Al3.3 Ti1.344 Si5.68 K2 O48 Name: Biotite Unit cell: 5.3183 9.211 10.105 90.0 100.09 90.0 , V=487.36 Space group: C12/M1 (12)

Ohta T , Takeda H , Takeuchi Y , American Mineralogist , 67 (1982) p.298-310, Mica polytypism: Similarities in the crystal structures of coexisting 1M and, 2M(1) oxybiotite, Sample: in the 2M1 setting