AM_Fersmanite Formula: (Ti2.39 Nb1.61) Ca5.49 Fe.03 Mn.03 Na2.37 Sr.08 Si4 O22 F3 Name: Fersmanite Unit cell: 10.183 10.183 20.396 90.0 97.19 90.0 , V=2098.30 Space group: C12/C1 (15)

Sokolova E V , Hawthorne F C , Khomyakov A P , The Canadian Mineralogist , 40 (2002) p.1421-1428, The crystal chemistry of fersmanite, Ca4(Na,Ca)4(Ti,Nb)4(Si2O7)2O8F3