AM_Dravite_10 Formula: Na.9 Ca.05 K.01 Mg2.679 Al6.09 Fe.12 Ti.03 B3 Si6 H6 O30.68 F.32 Name: Dravite Unit cell: 15.935 15.935 7.201 90.0 90.0 120.0 , V=1583.53 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: Parigi, Dora Maira, Western Alps, Italy