Pyroxene-ideal
Thompson R M, Downs R T
American Mineralogist 88 (2003) 653-666
Model pyroxenes I: Ideal pyroxene topologies
Pyroxene #10 based on stacking sequence ABACBABC. Ideal analogue to orthopyroxene.
Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
_database_code_amcsd 0003008
13.063945 6 3.4641016 90 90 90 *P2_1ca
0 .25 0
atom    x   y    z
SiA  9/32 1/6 7/12
SiB  7/32 2/3 5/12
Mg1a  1/8 1/3 5/12
Mg2a  1/8   0 5/12
SiC 15/32 1/6  1/4
SiD 17/32 5/6 7/12
Mg1b  7/8 2/3  3/4
Mg2b  7/8 1/2  1/4
O1A  3/16 1/6 7/12
O2A  5/16   0 5/12
O3A  5/16 1/3 5/12
O1B  5/16 2/3 5/12
O2B  3/16 1/2 7/12
O3B  3/16 5/6 7/12
O1C  9/16 1/6  1/4
O2C  7/16   0 1/12
O3C  7/16 1/6 7/12
O1D  7/16 5/6 7/12
O2D  9/16   0  3/4
O3D  9/16 5/6  1/4