AM_Dravite_11 Formula: Na.84 Ca.09 K.01 Mg2.643 Al5.805 Fe.48 Mn.06 Ti.021 Ni.021 Zn.009 B3 Si5.982 H3 O30.61 F.39 Name: Dravite Unit cell: 15.945 15.945 7.21 90.0 90.0 120.0 , V=1587.50 Space group: R3M (160)

Ertl A , Marschall H , Geister G , Henry D , Schertl H P , Ntaflos T , Luvizotto G , Nasdala L , Tillmanns E , American Mineralogist , 94 (2010) p.1-10, Metamorphic ultrahigh-pressure tourmaline: structure,, chemistry, and correlations to P-T conditions, Locality: Lago di Cignana, Western Alps, Italy