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 with O3-O3-O3 angle = 220 and model oxygen radius = 1
Note: Atoms Mg, Si, and O are assigned to atomic positions for convenience
_database_code_amcsd 0003472
7.565 6.510 3.759 90 115.8 90 C2/c
atom     x      y      z
Mg1      0  11/12    1/4
Mg2      0    .25    1/4
Si   .3100   1/12  .3551
O1   .1301   1/12  .1974
O2   .3699    .25  .3026
O3   .3699 -.0525  .2101