Pyroxene-ideal
Thompson R M, Downs R T
American Mineralogist 88 (2003) 653-666
Model pyroxenes I: Ideal pyroxene topologies
Pyroxene #3a based on stacking sequence ABABCACABCBC
Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
_database_code_amcsd 0002998
6.6332495 6 3.4641016 90 100.0250 90 P2/c
atom    x     y     z
SiA 11/16  7/12  5/16
SiB 13/16 11/12  1/48
Mg1a    0  7/12   3/4
Mg2a    0   .25   3/4
Mg1b  1/2  1/12   3/4
Mg2b  1/2   3/4   3/4
O1A   7/8  7/12   3/8
O2A   5/8   3/4 11/24
O3A   5/8  5/12 11/24
O1B   5/8  1/12 11/24
O2B   7/8   .25   3/8
O3B   7/8 11/12   3/8