Akermanite
      Yang H, Hazen R M, Downs R T, Finger L W
      Physics and Chemistry of Minerals 24 (1997) 510-519
      Structural change associated with the incommensurate-normal phase transition
      in akermanite, Ca2MgSi2O7, at high pressure
      Sample: P = 1.80 GPa
      _database_code_amcsd 0008034

      CELL PARAMETERS:    7.7937   7.7937   4.9696   90.000   90.000   90.000
      SPACE GROUP: P-42_1m   
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:    301.862
      Density (g/cm3):      2.999
      MAX. ABS. INTENSITY / VOLUME**2:      22.68128915    
      RIR:      2.463
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                16.08          9.52        5.5110    1   1   0         4
                17.85          1.23        4.9696    0   0   1         2
                21.20          7.43        4.1902    1   0   1         8
                22.82          2.89        3.8969    2   0   0         4
                24.11         11.37        3.6906    1   1   1         4
                25.56          3.97        3.4854    2   1   0         8
                29.12         22.54        3.0665    2   0   1         8
                31.35        100.00        2.8536    2   1   1         8
                32.49          3.74        2.7555    2   2   0         4
                36.15          1.49        2.4848    0   0   2         2
                36.46         16.36        2.4646    3   1   0         8
                37.31          5.90        2.4098    2   2   1         4
                38.01          6.04        2.3674    1   0   2         8
                39.13          7.12        2.3023    3   0   1         8
                39.79          2.58        2.2652    1   1   2         4
                40.87          1.66        2.2080    3   1   1         8
                44.79         13.30        2.0233    2   1   2         8
                45.77          2.61        1.9822    3   2   1         8
                46.61          6.01        1.9484    4   0   0         4
                48.14          6.57        1.8902    4   1   0         8
                49.39          4.16        1.8453    2   2   2         4
                49.63         10.21        1.8370    3   3   0         4
                51.74          9.42        1.7668    4   1   1         8
                52.28         20.22        1.7498    3   1   2         8
                52.51          6.18        1.7427    4   2   0         8
                53.16          3.37        1.7230    3   3   1         4
                55.47          1.01        1.6565    0   0   3         2
                56.42          2.29        1.6309    3   2   2         8
                58.15          1.68        1.5864    1   1   3         4
                60.75          1.40        1.5245    2   0   3         8
                62.03          4.69        1.4962    2   1   3         8
                62.92          1.31        1.4772    3   3   2         4
                63.70          2.57        1.4609    5   1   1         8
                65.78          4.78        1.4197    2   2   3         4
                67.00          2.84        1.3967    3   0   3         8
                67.39          9.28        1.3895    5   2   1         8
                68.05          3.00        1.3777    4   4   0         4
                70.99          1.66        1.3277    4   4   1         4
                71.44          1.39        1.3204    4   3   2         8
                72.81          3.30        1.2990    6   0   0         4
                76.11          1.52        1.2506    5   2   2         8
                76.46          4.28        1.2458    4   1   3         8
                76.71          1.31        1.2424    0   0   4         2
                76.83          1.13        1.2407    6   1   1         8
                77.61          2.23        1.2302    3   3   3         4
                80.26          1.90        1.1961    6   2   1         8
                81.40          2.44        1.1822    5   4   1         8
                81.83          1.17        1.1771    5   3   2         8
                84.09          2.06        1.1511    6   0   2         8
                85.55          1.47        1.1352    4   3   3         8
                86.67          2.42        1.1233    5   1   3         8
                86.91          1.21        1.1208    3   0   4         8
                88.04          1.13        1.1094    3   1   4         8
                88.58          1.12        1.1040    6   2   2         8
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       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.