AM_Richterite_46 Formula: Si7.96 Al.06 Mg4.46 Fe.52 Mn.04 Ca1.12 Na1.12 K.2 O24 H2 Name: Richterite Unit cell: 9.8787 18.024 5.2875 90.0 104.377 90.0 , V=911.98 Space group: C12/M1 (12)

Gunter M E , Dyar M D , Twamley B , Foit F F , Cornelius S , American Mineralogist , 88 (2003) p.1970-1978, Composition, Fe3+/Sum(Fe), and crystal structure of non-asbestiform and, asbestiform amphiboles from Libby, Montana, U.S.A.