Diopside Raudsepp M, Hawthorne F C, Turnock A C American Mineralogist 75 (1990) 1274-1281 Crystal chemistry of synthetic pyroxenes on the join CaNiSi2O6-CaMgSi2O6 (diopside): A Rietveld refinement study sample Ni25, CaNi.22Mg.78Si2O6 _database_code_amcsd 0001336 9.7393 8.9095 5.2418 90 105.850 90 C2/c atom x y z occ Biso Ni1 0 .9072 .25 .22 0.37 Mg1 0 .9072 .25 .78 0.37 Ca2 0 .3000 .25 .635 Si .2876 .0905 .2299 .349 O1 .1158 .0861 .1407 0.51 O2 .3633 .2488 .3218 0.65 O3 .3490 .0180 .9928 0.56