Pyroxene-ideal Thompson R M, Downs R T American Mineralogist 88 (2003) 653-666 Model pyroxenes I: Ideal pyroxene topologies Pyroxene #29b based on stacking sequence ABABABACACBC Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience. _database_code_amcsd 0003037 19.595917 6 3.4641016 90 90. 90 Pc atom x y z Mg1a 1/24 7/12 1/6 Mg2a 1/24 .25 1/6 SiA 5/48 1/12 0 SiB 7/48 5/12 1/3 Mg1b 5/24 1/12 2/3 Mg2b 5/24 .25 1/6 SiC 13/48 7/12 1/2 SiD 5/16 1/12 1/3 Mg1c 3/8 5/12 2/3 Mg2c 3/8 .25 1/6 SiE 7/16 11/12 1/2 SiF 23/48 5/12 1/3 Mg1d 13/24 1/12 1/3 Mg2d 13/24 .25 5/6 SiG 29/48 7/12 1/2 SiH 31/48 11/12 1/6 Mg1e 17/24 5/12 1/3 Mg2e 17/24 .25 5/6 SiJ 37/48 11/12 5/6 SiK 13/16 7/12 1/6 Mg1f 7/8 1/12 0 Mg2f 7/8 .25 1/2 SiL 15/16 7/12 1/2 SiM 47/48 11/12 1/6 O1A 1/6 1/12 0 O2A 1/12 .25 5/6 O3A 1/12 1/12 1/3 O1B 1/12 5/12 1/3 O2B 1/6 .25 1/2 O3B 1/6 5/12 0 O1C 1/3 5/12 0 O2C .25 3/4 1/3 O3C .25 5/12 1/3 O1D .25 1/12 1/3 O2D 1/3 .25 1/2 O3D 1/3 1/12 0 O1E 1/2 1/12 0 O2E 5/12 .25 5/6 O3E 5/12 1/12 1/3 O1F 5/12 5/12 1/3 O2F 1/2 .25 1/2 O3F 1/2 5/12 0 O1G 2/3 5/12 0 O2G 7/12 .25 1/6 O3G 7/12 7/12 1/6 O1H 7/12 1/12 2/3 O2H 2/3 .25 1/2 O3H 2/3 1/12 0 O1J 5/6 1/12 1/3 O2J 3/4 .25 1/6 O3J 3/4 1/12 2/3 O1K 3/4 7/12 1/6 O2K 5/6 3/4 1/3 O3K 5/6 5/12 1/3 O1L 0 5/12 0 O2L 11/12 .25 1/6 O3L 11/12 7/12 1/6 O1M 11/12 1/12 2/3 O2M 0 .25 1/2 O3M 0 1/12 0