Dawsonite
Diffraction data computed using the structure from the paper listed below, 
along with the cell parameters refined from single crystal data of R050645
      Frueh A J, Golightly J P
      The Canadian Mineralogist 9 (1967) 51-56
      The crystal structure of dawsonite NaAl(CO3)(OH)2
      Locality: McGill University, Montreal, Quebec, Canada

      CELL PARAMETERS:   6.7550 10.4160  5.5780   90.000   90.000   90.000
      SPACE GROUP: Imam      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Na     0.25000   0.75000   0.25000     1.000     0.030
            Al     0.00000   0.50000   0.00000     1.000     0.030
            C      0.00000   0.25400   0.25000     1.000     0.030
            O      0.00000   0.13300   0.25000     1.000     0.030
            O      0.00000   0.31500   0.05200     1.000     0.030
            OH     0.18000   0.52500   0.25000     1.000     0.030

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    0.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  6 +/-  9 +/-  5
            MAX. ABS. INTENSITY / VOLUME**2:      15.44460671    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                15.64        100.00        5.6675    1   1   0
                18.04          1.54        4.9173    0   1   1
                26.39         13.17        3.3775    2   0   0
                26.88          4.39        3.3164    1   2   1
                28.91          4.44        3.0880    1   3   0
                32.09          4.09        2.7890    0   0   2
                32.15         58.40        2.7840    2   1   1
                34.44         15.96        2.6040    0   4   0
                35.89         13.40        2.5024    1   1   2
                36.55          1.10        2.4586    0   2   2
                40.50          2.06        2.2276    1   4   1
                40.62          2.92        2.2208    2   3   1
                42.01         18.20        2.1506    2   0   2
                43.74          2.51        2.0698    1   3   2
                43.90          1.40        2.0622    2   4   0
                45.57         14.86        1.9907    1   5   0
                45.64          1.36        1.9878    2   2   2
                46.54          7.74        1.9515    0   5   1
                49.82          2.11        1.8304    0   1   3
                52.73          1.30        1.7360    0   6   0
                53.00         18.98        1.7277    3   1   2
                54.10          4.01        1.6951    1   2   3
                54.29          2.74        1.6898    2   5   1
                54.32          7.72        1.6888    4   0   0
                55.41         14.82        1.6582    2   4   2
                56.82          2.63        1.6203    1   5   2
                57.25          1.60        1.6093    2   1   3
                57.36          1.26        1.6064    4   2   0
                59.06          1.01        1.5641    3   3   2
                59.91          3.94        1.5440    2   6   0
                60.55          1.93        1.5291    3   5   0
                63.08          3.12        1.4738    0   6   2
                65.93          1.43        1.4169    4   4   0
                67.12          4.51        1.3945    0   0   4
                67.26          4.20        1.3920    4   2   2
                69.41          1.58        1.3541    1   1   4
                69.60          1.72        1.3508    2   6   2
                70.19          4.44        1.3408    3   5   2
                70.26          1.77        1.3398    5   1   0
                70.55          2.09        1.3349    3   6   1
                73.48          1.13        1.2887    1   7   2
                73.85          2.01        1.2832    2   5   3
                74.69          1.94        1.2709    1   3   4
                75.73          1.49        1.2559    3   4   3
                77.67          2.26        1.2293    0   4   4
                84.90          1.88        1.1421    1   5   4
                85.65          1.66        1.1341    3   7   2
                85.71          1.96        1.1335    5   5   0
                87.94          3.85        1.1104    4   6   2
                89.13          1.18        1.0986    2   7   3
                89.25          1.31        1.0974    6   1   1
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.