AM_Vermiculite_2 Formula: Mg1.338 Fe.24 Al.721 Si1.36 O9 H3 Name: Vermiculite Unit cell: 5.33 9.18 28.9 90.0 97.0 90.0 , V=1403.52 Space group: C1C1 (9)

Mathieson A M , Walker G F , American Mineralogist , 39 (1954) p.231-255, Crystal structure of magnesium-vermiculite