Pyroxene-ideal
Thompson R M, Downs R T
American Mineralogist 88 (2003) 653-666
Model pyroxenes I: Ideal pyroxene topologies
Pyroxene #9b based on stacking sequence ABABCBAC
Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
_database_code_amcsd 0003007
13.063945 6 3.4641016 90 90. 90 P2_1/c
atom    x   y   z
SiA 31/32 1/6 1/3
Mg1a  7/8 2/3 1/2
Mg2a  7/8   0 1/2
SiB  9/32 1/3 1/6
SiC  7/32 2/3 1/2
SiD 15/32 1/6 1/3
Mg1b  3/8 2/3 5/6
Mg2b  3/8   0 5/6
O1A  1/16 1/6 1/3
O2A 15/16   0 1/6
O3A 15/16 1/3 1/6
O1B  3/16 1/3 1/6
O2B  5/16 1/2   0
O3B  5/16 1/3 1/2
O1C  5/16 2/3 1/2
O2C  3/16 1/2 2/3
O3C  3/16 2/3 1/6
O1D  9/16 1/6 1/3
O2D  7/16   0 1/6
O3D  7/16 1/3 1/6