Brownmillerite
Diffraction data computed using the structure from the paper listed below,
along with the cell parameters refined from single crystal data of R130105
      Redhammer G J, Tippelt G, Roth G, Amthauer G
      American Mineralogist 89 (2004) 405-420
      Structural variations in the brownmillerite series Ca2(Fe2-xAlx)O5:
      Single-crystal X-ray diffraction at 25 deg C and high temperature
      X-ray powder diffraction (25 C <= T <= 1000 C)
      Sample: bht095_2
      _database_code_amcsd 0003437

      CELL PARAMETERS:   5.3530 14.5040  5.5830   90.000   90.000   90.000
      SPACE GROUP: I2mb      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Ca     0.49130   0.10859   0.02718     1.000     0.490
            Fe     0.00050   0.00000   0.00000     0.783     0.292
            Al     0.00050   0.00000   0.00000     0.217     0.292
            Fe     0.95270   0.25000   0.92830     0.351     0.213
            Al     0.95270   0.25000   0.92830     0.649     0.213
            O      0.24940   0.98640   0.25290     1.000     0.490
            O      0.02160   0.14330   0.06860     1.000     0.695
            O      0.61460   0.25000   0.86330     1.000     0.553

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    5.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  4 +/- 13 +/-  5
            MAX. ABS. INTENSITY / VOLUME**2:      27.31428912    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                12.20         31.17        7.2520    0   2   0
                17.02          2.86        5.2103    0   1   1
                23.02          5.96        3.8639    1   0   1
                24.35         12.02        3.6548    0   3   1
                24.55          3.75        3.6260    0   4   0
                26.13          3.77        3.4101    1   2   1
                32.06         35.17        2.7915    0   0   2
                33.48         44.40        2.6765    2   0   0
                33.90        100.00        2.6441    1   4   1
                34.85         10.15        2.5741    0   5   1
                36.84          3.65        2.4399    1   1   2
                40.79          3.73        2.2119    0   4   2
                41.83          5.54        2.1594    2   3   1
                41.96          3.41        2.1534    2   4   0
                44.19         23.49        2.0493    1   6   1
                47.04         44.32        1.9319    2   0   2
                48.34          2.66        1.8829    1   5   2
                48.78         11.10        1.8668    2   2   2
                50.33         18.31        1.8130    0   8   0
                50.90          1.45        1.7940    2   6   0
                52.70          7.75        1.7368    0   3   3
                55.53          1.73        1.6548    3   2   1
                56.03          2.18        1.6413    1   8   1
                58.05          2.80        1.5888    1   7   2
                58.34         17.66        1.5817    1   4   3
                58.97          2.59        1.5664    0   5   3
                60.12         19.91        1.5390    3   4   1
                60.93          6.30        1.5205    0   8   2
                61.81          8.26        1.5010    2   8   0
                62.06          2.45        1.4954    3   1   2
                63.90          4.23        1.4569    2   3   3
                65.68          4.75        1.4217    1   6   3
                67.05          2.24        1.3958    0   0   4
                67.35          5.46        1.3904    3   6   1
                68.45          4.01        1.3706    0   2   4
                69.18          2.62        1.3579    1  10   1
                69.54          3.57        1.3519    2   5   3
                69.96          1.70        1.3448    1   1   4
                70.35          4.84        1.3383    4   0   0
                70.56          1.13        1.3348    3   5   2
                71.34         12.91        1.3220    2   8   2
                71.72          2.19        1.3160    4   2   0
                77.06          1.29        1.2376    2   0   4
                78.39          1.05        1.2199    2   2   4
                78.62          1.73        1.2169    3   7   2
                78.87          4.81        1.2137    3   4   3
                79.41          3.23        1.2067    4   0   2
                83.31          3.28        1.1599    2  10   2
                83.87          3.60        1.1535    1  12   1
                85.41          2.91        1.1367    3   6   3
                85.90          2.59        1.1314    1   7   4
                88.38          1.17        1.1060    0   8   4
                88.65          1.41        1.1033    3  10   1
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.