Pyroxene-ideal
      Thompson R M, Downs R T
      American Mineralogist 88 (2003) 653-666
      Model pyroxenes I: Ideal pyroxene topologies
      Pyroxene #4 based on CCP stacking sequence ABCABCABCABC. Ideal analogue of HP-C2/c
      pyroxene and eight-coordinaSiEd Mg2-C2/c pyroxene.
      Note: Atoms Mg, Si, and O are assigned to atomic positions just for convenience.
      _database_code_amcsd 0003000

      CELL PARAMETERS:    6.6333   6.0000   3.4641   90.000  100.025   90.000
      SPACE GROUP: C2/c      
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:    135.764
      Density (g/cm3):      9.821
      MAX. ABS. INTENSITY / VOLUME**2:      24.76995595    
      RIR:      0.821
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                27.31          2.97        3.2660    2   0   0         2
                29.78          6.30        3.0000    0   2   0         2
                31.18          2.47        2.8685   -1   1   1         4
                35.07          4.91        2.5584    1   1   1         4
                40.02         11.29        2.2528    0   2   1         4
                40.84         20.80        2.2094    2   2   0         4
                44.25         68.65        2.0467    3   1   0         4
                46.25         21.89        1.9629   -2   2   1         4
                47.95         19.79        1.8974   -3   1   1         4
                51.89         41.31        1.7621    2   2   1         4
                53.74         66.67        1.7056   -1   3   1         4
                53.74         33.33        1.7056    0   0   2         2
                55.41          4.18        1.6581   -1   1   2         4
                56.06          7.56        1.6406    3   1   1         4
                56.34          3.14        1.6330    4   0   0         2
                56.34          6.29        1.6330    1   3   1         4
                56.34          3.14        1.6330   -2   0   2         2
                60.44          9.03        1.5317    1   1   2         4
                65.22         19.36        1.4304   -3   1   2         4
                66.07         17.07        1.4142   -3   3   1         4
                66.07          8.54        1.4142    2   0   2         2
                66.78          6.42        1.4009   -4   2   1         4
                68.31          2.30        1.3731    0   4   1         4
                68.88          3.79        1.3631    2   4   0         4
                72.83          4.78        1.2987   -2   4   1         4
                74.12          4.73        1.2792    2   2   2         4
                74.30          1.85        1.2765    5   1   0         4
                77.23         11.17        1.2352    2   4   1         4
                78.68          3.71        1.2161    3   1   2         4
                80.67          2.29        1.1911   -4   2   2         4
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.