Pyroxene-ideal
Thompson R M, Downs R T
American Mineralogist 88 (2003) 653-666
Model pyroxenes I: Ideal pyroxene topologies
Pyroxene #1 based on HCP stacking sequence ABAB. Has the bonding topology of
observed HT-C2/c pyroxenes.
Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
_database_code_amcsd 0002996
7.3936910 6 3.4641016 90 117.9383 90 C2/c
atom  x     y     z
Mg1   0 11/12   1/4
Mg2   0   .25   1/4
Si 5/16  1/12 19/48
O1  1/8  1/12  5/24
O2  3/8   .25  7/24
O3  3/8 11/12  7/24