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 ferrosilite at 1.87 GPa after Hugh-Jones et al. (1995) with O3-O3-O3 angle = 138.3 and model oxygen radius = 1.366 _database_code_amcsd 0003482 9.552 8.844 5.106 90 103.8 90 C2/c atom x y z Fe 0 11/12 1/4 Fe 0 .25 1/4 Si .3101 1/12 .2219 O1 .1298 1/12 .1413 O2 .3702 .25 .3587 O3 .3702 .0550 .9438