AM_Dumortierite_3 Formula: Si2.95 Al6.73 B O18 Name: Dumortierite Unit cell: 11.802 20.222 4.695 90.0 90.0 90.0 , V=1120.51 Space group: PMCN (62)

Alexander V D , Griffen D T , Martin T J , American Mineralogist , 71 (1986) p.786-794, Crystal chemistry of some Fe- and Ti-poor dumortierites, Sample: #11, USNM 141800, from Ambositra, Madagascar