Pyroxene-ideal Thompson R M, Downs R T American Mineralogist 89 (2004) 614-628 Model pyroxenes II: Structural variation as a function of tetrahedral rotation model spodumene after Cameron et al. (1973) with O3-O3-O3 angle = 189.5 and model oxygen radius = 1.263 _database_code_amcsd 0003487 9.570 8.717 5.033 90 112.1 90 C2/c atom x y z Al 0 11/12 1/4 Li 0 .25 1/4 Si .3081 1/12 .3035 O1 .1337 1/12 .1789 O2 .3662 .25 .3211 O3 .3662 -.0120 .1070