Witherite
Diffraction data computed using the structure from the paper listed below, 
along with the cell parameters refined from the powder pattern of R050148
      de Villiers J P R
      American Mineralogist 56 (1971) 758-767
      Crystal structures of aragonite, strontianite, and witherite

      CELL PARAMETERS:   5.3048  8.8854  6.4216   90.000   90.000   90.000
      SPACE GROUP: Pmcn      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Ba     0.25000   0.41630   1.75490     1.000     0.461
            C      0.25000   0.75700  -0.08100     1.000     1.115
            O      0.25000   0.90110  -0.08780     1.000     1.195
            O      0.45950   0.68390  -0.07900     1.000     1.000

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    5.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  4 +/-  8 +/-  5
            MAX. ABS. INTENSITY / VOLUME**2:      95.49525267    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                19.49          8.26        4.5548    1   1   0
                19.99          3.81        4.4427    0   2   0
                23.95        100.00        3.7151    1   1   1
                24.36         50.99        3.6536    0   2   1
                27.79         14.36        3.2108    0   0   2
                29.58          4.17        3.0197    0   1   2
                32.60          2.97        2.7468    1   0   2
                33.79         14.78        2.6524    2   0   0
                34.17         21.77        2.6243    1   1   2
                34.46         10.75        2.6023    0   2   2
                34.69         27.18        2.5860    1   3   0
                39.57          7.01        2.2774    2   2   0
                40.61          2.72        2.2213    0   4   0
                42.10         32.32        2.1464    2   2   1
                43.09         15.10        2.0993    0   4   1
                44.30         14.43        2.0449    2   0   2
                45.01         26.48        2.0140    1   3   2
                46.90         20.17        1.9373    1   1   3
                47.13          9.68        1.9284    0   2   3
                49.04          4.01        1.8576    2   2   2
                49.92          2.33        1.8268    0   4   2
                52.79          2.10        1.7343    3   1   0
                53.83          1.97        1.7030    2   4   0
                54.45          1.49        1.6850    1   5   0
                54.83          8.98        1.6743    3   1   1
                55.85          8.69        1.6461    2   4   1
                56.46          8.43        1.6299    1   5   1
                57.40          2.12        1.6054    0   0   4
                59.24          4.64        1.5597    2   2   3
                60.02          2.06        1.5414    0   4   3
                60.69          2.47        1.5259    3   1   2
                61.03          4.34        1.5183    3   3   0
                61.22          3.29        1.5141    1   1   4
                61.41          1.51        1.5098    0   2   4
                61.65          2.56        1.5045    2   4   2
                62.22          2.44        1.4921    1   5   2
                62.74          2.23        1.4809    0   6   0
                68.29          3.39        1.3734    2   0   4
                68.34          7.46        1.3726    3   3   2
                68.83          7.06        1.3639    1   3   4
                69.80          6.35        1.3475    3   1   3
                69.96          3.38        1.3448    0   6   2
                70.69          5.93        1.3327    2   4   3
                71.08          2.35        1.3262    4   0   0
                71.22          5.93        1.3240    1   5   3
                71.96          1.27        1.3122    2   2   4
                73.20          4.37        1.2930    2   6   0
                76.40          3.91        1.2466    4   2   1
                77.17          3.46        1.2361    1   1   5
                77.34          1.62        1.2338    0   2   5
                77.61          3.76        1.2302    3   5   1
                77.94          1.89        1.2258    4   0   2
                78.98          3.25        1.2123    1   7   1
                79.99          3.48        1.1994    2   6   2
                81.45          1.24        1.1816    4   2   2
                81.74          1.08        1.1781    3   1   4
                82.59          1.01        1.1682    2   4   4
                82.64          1.21        1.1676    3   5   2
                83.10          1.02        1.1623    1   5   4
                83.99          1.18        1.1523    1   7   2
                86.88          3.06        1.1212    4   4   1
                87.12          3.23        1.1187    2   2   5
                87.79          1.61        1.1119    0   4   5
                88.67          3.65        1.1031    3   3   4
                89.56          1.48        1.0944    0   8   1
                89.74          2.46        1.0927    4   2   3
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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.