Pyroxene-ideal
      Thompson R M, Downs R T
      American Mineralogist 88 (2003) 653-666
      Model pyroxenes I: Ideal pyroxene topologies
      Pyroxene #7 based on stacking sequence ABABACAC
      Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
      _database_code_amcsd 0003003

      CELL PARAMETERS:   13.0639   6.0000   3.4641   90.000   90.000   90.000
      SPACE GROUP: P2_1ca    
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:    271.529
      Density (g/cm3):      9.821
      MAX. ABS. INTENSITY / VOLUME**2:      17.00442908    
      RIR:      0.564
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                20.10          1.28        4.4188    2   1   0         2
                27.31          4.32        3.2660    4   0   0         1
                29.78          9.18        3.0000    0   2   0         2
                29.78         12.97        3.0000    0   1   1         4
                30.57         28.11        2.9239    1   1   1         4
                40.37         10.69        2.2344    1   2   1         4
                40.84         30.30        2.2094    4   2   0         2
                40.84         12.88        2.2094    4   1   1         4
                42.18         71.84        2.1423    2   2   1         4
                44.25        100.00        2.0467    6   1   0         2
                45.07         33.48        2.0114    3   2   1         4
                46.07          6.30        1.9703    5   1   1         4
                52.86          1.19        1.7321    0   3   1         4
                53.36         14.27        1.7170    1   3   1         4
                53.36          7.13        1.7170    1   0   2         2
                53.50          7.86        1.7126    5   2   1         4
                55.68          3.83        1.6508    1   1   2         4
                56.34          4.58        1.6330    8   0   0         1
                57.12         27.40        1.6126    2   1   2         4
                57.24         41.34        1.6094    3   3   1         4
                57.24         20.67        1.6094    3   0   2         2
                58.22          4.47        1.5847    7   1   1         4
                58.79          3.56        1.5706    6   2   1         4
                59.46         13.51        1.5545    3   1   2         4
                60.50         31.55        1.5302    4   3   1         4
                60.50         15.77        1.5302    4   0   2         2
                61.85          1.33        1.5000    0   2   2         4
                62.31          3.02        1.4902    1   2   2         4
                64.55         16.32        1.4436    5   3   1         4
                64.55          8.16        1.4436    5   0   2         2
                65.03          6.32        1.4343    8   1   1         4
                66.63          3.76        1.4036    5   1   2         4
                68.55          1.92        1.3689    1   4   1         4
                68.88          5.52        1.3631    4   4   0         2
                68.88          2.45        1.3631    4   2   2         4
                69.83         14.28        1.3469    2   4   1         4
                71.33          1.93        1.3222    6   1   2         4
                71.94          7.08        1.3125    3   4   1         4
                72.69          1.38        1.3009    5   2   2         4
                74.30          2.69        1.2765   10   1   0         2
                74.78         11.62        1.2695    7   3   1         4
                74.78          5.81        1.2695    7   0   2         2
                78.19          5.00        1.2226    9   2   1         4
                78.55          2.20        1.2178    5   4   1         4
                80.91         22.00        1.1882    8   3   1         4
                80.91         11.00        1.1882    8   0   2         2
                82.50          1.42        1.1692    7   2   2         4
                83.00          1.25        1.1635    6   4   1         4
                85.85          3.66        1.1320   10   2   1         4
                86.07          1.07        1.1296    1   5   1         4
                86.07          1.07        1.1296    1   4   2         4
                87.73         18.72        1.1125    9   3   1         4
                87.73          9.36        1.1125    9   0   2         2
                88.51          2.57        1.1047    8   2   2         4
                89.62          3.39        1.0939    9   1   2         4
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.