AM_Piemontite Formula: Ca1.87 Sr.13 Si3 Al1.97 Mn.72 Fe.31 O13 H Name: Piemontite Unit cell: 8.878 5.692 10.201 90.0 115.4 90.0 , V=465.66 Space group: P121/M1 (11)

Dollase W A , American Mineralogist , 54 (1969) p.710-717, Crystal structure and cation ordering of piemontite