AM_Richterite_23 Formula: Si8 (Mg3.91 Co1.09) Ca1.1 Na2.72 O24 Name: Richterite Unit cell: 9.918 17.999 5.2714 90.0 104.246 90.0 , V=912.08 Space group: C12/M1 (12)

Della Ventura G , Robert J-L , Raudsepp M , Hawthorne F C , Welch M D , American Mineralogist , 82 (1997) p.291-301, Site occupancies in synthetic monoclinic amphiboles: Rietveld structure, refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite, Sample: Co20