AM_Piemontite_7 Formula: Ca2 (Al2 Mn) Si3 O13 H Name: Piemontite Unit cell: 8.8531 5.6741 10.1613 90.0 115.519 90.0 , V=460.64 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 = 1.0, p = 1.00, Synthesis at P=200 MPa, T=500 C