Pyroxene-ideal
Thompson R M, Downs R T
American Mineralogist 88 (2003) 653-666
Model pyroxenes I: Ideal pyroxene topologies
Pyroxene #11b based on stacking sequence ABABABABCABC
Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
_database_code_amcsd 0003010
19.595917 6 3.4641016 90 90. 90 P2_1/c
atom    x   y   z
Mg1a 1/12 2/3 1/2
Mg2a 1/12 1/2   0
Mg1b  .25 1/3 1/2
Mg2b  .25 1/2   0
Mg1c 5/12 5/6 2/3
Mg2c 5/12 1/2 2/3
SiA  7/48 1/6 1/3
SiB  3/16 5/6 2/3
SiC  5/16 2/3 1/2
SiD 17/48 1/3 1/6
SiE 23/48 1/6 2/3
SiF  1/48 1/6 2/3
O1A  5/24 1/6 1/3
O2A   1/8   0 1/6
O3A   1/8 1/6 2/3
O1B   1/8 5/6 2/3
O2B  5/24   0 5/6
O3B  5/24 5/6 1/3
O1C   3/8 2/3 1/2
O2C  7/24 1/2 2/3
O3C  7/24 5/6 2/3
O1D  7/24 1/3 1/6
O2D   3/8 1/2   0
O3D   3/8 1/6   0
O1E 13/24 1/6 2/3
O2E 11/24   0 5/6
O3E 11/24 1/6 1/3
O1F 23/24 1/6 2/3
O2F  1/24   0 5/6
O3F  1/24 1/6 1/3