Pyroxene-ideal Thompson R M, Downs R T American Mineralogist 88 (2003) 653-666 Model pyroxenes I: Ideal pyroxene topologies Pyroxene #11a based on stacking sequence ABABABABCABC Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience. _database_code_amcsd 0003009 19.595917 6 3.4641016 90 90. 90 P2/c atom x y z SiA 1/16 7/12 5/12 SiB 5/48 1/12 7/12 SiC 11/48 1/12 11/12 SiD 13/48 5/12 7/12 SiE 19/48 5/12 7/12 SiF 7/16 1/12 1/4 Mg1a 0 1/12 1/4 Mg2a 0 .25 3/4 Mg1b 1/6 5/12 1/4 Mg2b 1/6 .25 3/4 Mg1c 1/3 1/12 7/12 Mg2c 1/3 .25 1/12 Mg1d 1/2 5/12 1/4 Mg2d 1/2 .25 3/4 O1A 1/8 7/12 5/12 O2A 1/24 3/4 7/12 O3A 1/24 5/12 7/12 O1B 1/24 1/12 7/12 O2B 1/8 .25 5/12 O3B 1/8 1/12 11/12 O1C 7/24 1/12 11/12 O2C 5/24 .25 1/12 O3C 5/24 1/12 7/12 O1D 5/24 5/12 7/12 O2D 7/24 .25 5/12 O3D 7/24 7/12 5/12 O1E 11/24 5/12 7/12 O2E 3/8 .25 3/4 O3E 3/8 7/12 3/4 O1F 3/8 1/12 1/4 O2F 11/24 .25 1/12 O3F 11/24 1/12 7/12