AM_Piemontite_4 Formula: Ca2 Al2.54 Mn.46 Si3 O13 H Name: Piemontite Unit cell: 8.856 5.6291 10.148 90.0 115.516 90.0 , V=456.55 Space group: P121/M1 (11)

Nagashima M , Akasaka M , American Mineralogist , 89 (2004) p.1119-1129, An X-ray Rietveld study of piemontite on the join, Ca2Al3Si3O12(OH) - Ca2Mn3+3Si3O12(OH) formed by hydrothermal synthesis, Sample: q = 0.5, p = 0.5, Synthesis at P=350 MPa, T=500 C