AM_Cordierite_14 Formula: O18.85 Al3.84 Be.16 Si5 (Mg1.06 Fe.58 Li.36) Na.36 H.85 Name: Cordierite Unit cell: 17.056 9.783 9.335 90.0 90.0 90.0 , V=1557.63 Space group: CCCM (66)

Armbruster T , American Mineralogist , 71 (1986) p.746-757, Role of Na in the structure of low-cordierite: A single-crystal X-ray study, Sample: from a pelitic schist, south-central Maine, USA (Ferry)