AM_Piemontite_5 Formula: Ca2 (Al2.25 Mn.75) Si3 O13 H Name: Piemontite Unit cell: 8.853 5.6596 10.1501 90.0 115.511 90.0 , V=458.98 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 = 0.75, p = 0.75, Synthesis at P=200 MPa, T=500 C