AM_Cummingtonite_13 Formula: Fe3.471 Mg3.445 Al.008 Ca.076 Si8 O24 Name: Cummingtonite Unit cell: 9.2099 17.7605 5.193 90.0 103.173 90.0 , V=827.08 Space group: P121/M1 (11)

Yang H , Hazen R M , Prewitt C T , Finger L W , Lu R , Hemley R J , American Mineralogist , 83 (1998) p.288-299, High-pressure single-crystal X-ray diffraction and infrared spectroscopic