AM_Biotite_12 Formula: Si2.856 Al1.369 (K.955 Ca.03 Na.015) Mg2.166 Cr.048 Fe.39 Mn.021 Ti.144 O12 Name: Biotite Unit cell: 5.317 9.207 10.232 90.0 99.98 90.0 , V=493.31 Space group: C12/M1 (12)

Brigatti M F , Galli E , Poppi L , American Mineralogist , 76 (1991) p.1174-1183, Effect of Ti substitution in biotite-M crystal chemistry, Sample 8 from a lamproite rock, Puebla De Mula, Spain