Anhydrite
Diffraction data computed using the structure from the paper listed below, 
along with the cell parameters refined from the powder pattern of R040061
      Hawthorne F C, Ferguson R B
      The Canadian Mineralogist 13 (1975) 289-292
      Anhydrous sulphates. II. Refinement of the crystal structure of anhydrite

      CELL PARAMETERS:   6.9984  6.9927  6.2383   90.000   90.000   90.000
      SPACE GROUP: Amma      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Ca     0.75000   0.00000   0.34760     1.000     0.653
            S      0.25000   0.00000   0.15556     1.000     0.550
            O      0.25000   0.16990   0.01620     1.000     0.985
            O      0.08190   0.00000   0.29750     1.000     0.938

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    5.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  6 +/-  6 +/-  5
            MAX. ABS. INTENSITY / VOLUME**2:      15.79858691    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                22.95          8.84        3.8760    1   1   1
                25.45        100.00        3.4992    2   0   0
                25.48         98.45        3.4964    0   2   0
                28.62          3.94        3.1191    0   0   2
                31.40         59.89        2.8490    1   0   2
                32.00          5.88        2.7971    2   1   1
                36.32         13.93        2.4733    2   2   0
                38.67          2.42        2.3284    2   0   2
                38.69         33.79        2.3275    0   2   2
                40.86         38.72        2.2086    1   2   2
                41.35         12.17        2.1835    0   3   1
                43.39         12.23        2.0856    3   1   1
                45.51          8.96        1.9932    0   1   3
                46.88          6.34        1.9380    2   2   2
                48.75         27.72        1.8681    3   0   2
                49.19          6.05        1.8524    2   3   1
                52.29         10.26        1.7496    4   0   0
                52.33         10.53        1.7482    0   4   0
                55.79         27.57        1.6477    3   2   2
                57.84          4.74        1.5941    3   3   1
                59.04          3.63        1.5646    4   2   0
                59.07          3.89        1.5639    2   4   0
                60.73          5.46        1.5250    0   4   2
                60.85          1.01        1.5222    1   0   4
                61.18          1.25        1.5149    1   3   3
                62.31          9.83        1.4900    1   4   2
                65.53          1.55        1.4245    2   0   4
                65.54          3.99        1.4243    0   2   4
                65.84          1.77        1.4185    2   3   3
                66.90          1.91        1.3985    4   2   2
                66.93          1.46        1.3980    2   4   2
                67.06          3.91        1.3957    1   2   4
                68.75          1.40        1.3653    4   3   1
                71.52          9.04        1.3192    2   2   4
                72.97          3.14        1.2965    3   0   4
                74.27          3.40        1.2770    5   0   2
                74.31          9.98        1.2764    3   4   2
                77.13          1.88        1.2366    4   4   0
                78.72          7.39        1.2156    3   2   4
                79.99          4.33        1.1995    5   2   2
                82.74          3.98        1.1664    6   0   0
                82.83          3.96        1.1654    0   6   0
                82.97          1.72        1.1638    0   4   4
                84.37          1.90        1.1480    1   4   4
                88.33          3.36        1.1065    6   2   0
                88.41          3.35        1.1057    2   6   0
                88.52          4.59        1.1046    4   2   4
                88.55          4.36        1.1043    2   4   4
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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.