AM_Biotite_21 Formula: (Si2.784 Al1.216) Fe1.215 Mg1.545 Mn.018 Ti.225 K.946 Na.032 O12 Name: Biotite Unit cell: 5.339 9.249 20.196 90.0 95.06 90.0 , V=993.40 Space group: C12/C1 (15)

Bigi S , Brigatti M F , American Mineralogist , 79 (1994) p.63-72, Crystal chemistry and microstructures of plutonic biotite, Sample 2M1 from Valle del Cervo syenitic complex