AM_Dravite_2 Formula: Na.814 K.014 Ca.009 Ti.03 Cr.006 Fe.612 Mn.003 Mg2.274 Al6.078 Si6 B3 O34 Name: Dravite Unit cell: 15.947 15.947 7.214 90.0 90.0 120.0 , V=1588.78 Space group: R3M (160)

Hawthorne F C , MacDonald D J , Burns P C , American Mineralogist , 78 (1993) p.265-270, Reassignment of cation site occupancies in tourmaline: Al-Mg disorder in the, crystal structure of dravite