AM_Norbergite Formula: Mg3 Si O4.2 (F1.8 H.2) Name: Norbergite Unit cell: 4.7104 10.2718 8.7476 90.0 90.0 90.0 , V=423.25 Space group: PBNM (62)

Gibbs G V , Ribbe P H , American Mineralogist , 54 (1969) p.376-390, The crystal structures of the humite minerals: I. Norbergite