Formula: O24 Si8 Ti.86 Mn.37 Mg2.13 Fe.71 Al.03 Na2.66 Ca2 K.18
Name: Obertiite
Unit cell: 9.776 17.919 5.292 90.0 104.05 90.0 , V=899.30
Space group: C12/M1 (12)

Hawthorne F C , Cooper M A , Grice J D , Ottolini L , American Mineralogist , 85 (2000) p.236-241, A new anhydrous amphibole from the Eifel region, Germany:, Description and crystal structure of obertiite, NaNa2(Mg3FeTi)Si8O22O2, Note: M1A and M1 are interchanged in the bond length table