Richterite Della Ventura G, Robert J-L, Raudsepp M, Hawthorne F C, Welch M D American Mineralogist 82 (1997) 291-301 Site occupancies in synthetic monoclinic amphiboles: Rietveld structure refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite Sample: Co20 _database_code_amcsd 0001881 9.9180 17.999 5.2714 90 104.246 90 C2/m atom x y z occ Si1 .2822 .0854 .2953 Si2 .2821 .1699 .7983 Mg1 0 .0893 .5 .77 Co1 0 .0893 .5 .23 Mg2 0 .1789 0 .80 Co2 0 .1789 0 .20 Mg3 0 0 0 .77 Co3 0 0 0 .23 Ca4 0 .2742 .5 .55 Na4 0 .2742 .5 .45 NaA 0 .4794 0 .91 O1 .1163 .0879 .2163 O2 .1057 .1703 .7226 O3 .1065 0 .7102 O4 .3554 .2474 .7775 O5 .3418 .1309 .0828 O6 .3402 .1132 .5915 O7 .3397 0 .3037