Pyroxene-ideal Thompson R M, Downs R T American Mineralogist 88 (2003) 653-666 Model pyroxenes I: Ideal pyroxene topologies Pyroxene #29a based on stacking sequence ABABABACACBC Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience. _database_code_amcsd 0003036 19.595917 6 3.4641016 90 90. 90 Pc atom x y z SiA 1/48 7/12 5/6 SiB 1/16 11/12 1/2 Mg1a 1/8 7/12 1/6 Mg2a 1/8 .25 1/6 SiC 3/16 11/12 5/6 SiD 11/48 7/12 1/2 Mg1b 7/24 11/12 1/6 Mg2b 7/24 .25 1/6 SiE 17/48 7/12 5/6 SiF 19/48 11/12 1/2 Mg1c 11/24 7/12 1/6 Mg2c 11/24 .25 1/6 SiG 25/48 1/12 2/3 SiH 9/16 5/12 0 Mg1d 5/8 1/12 1/3 Mg2d 5/8 .25 5/6 SiJ 11/16 7/12 1/6 SiK 35/48 11/12 1/2 Mg1e 19/24 7/12 1/2 Mg2e 19/24 .25 1/2 SiL 41/48 11/12 1/6 SiM 43/48 5/12 1/3 Mg1f 23/24 11/12 5/6 Mg2f 23/24 .25 5/6 O1A 1/12 7/12 5/6 O2A 0 3/4 0 O3A 0 5/12 0 O1B 0 1/12 0 O2B 1/12 .25 5/6 O3B 1/12 1/12 1/3 O1C .25 1/12 1/3 O2C 1/6 .25 1/2 O3C 1/6 1/12 0 O1D 1/6 5/12 0 O2D .25 .25 5/6 O3D .25 5/12 1/3 O1E 5/12 5/12 1/3 O2E 1/3 .25 1/2 O3E 1/3 7/12 1/2 O1F 1/3 1/12 0 O2F 5/12 .25 5/6 O3F 5/12 1/12 1/3 O1G 7/12 1/12 2/3 O2G 1/2 .25 1/2 O3G 1/2 1/12 0 O1H 1/2 5/12 0 O2H 7/12 .25 1/6 O3H 7/12 7/12 1/6 O1J 3/4 5/12 2/3 O2J 2/3 .25 1/2 O3J 2/3 5/12 0 O1K 2/3 1/12 0 O2K 3/4 .25 1/6 O3K 3/4 1/12 2/3 O1L 11/12 1/12 2/3 O2L 5/6 .25 5/6 O3L 5/6 1/12 1/3 O1M 5/6 5/12 1/3 O2M 11/12 .25 1/6 O3M 11/12 7/12 1/6