Smithsonite
Diffraction data computed using the structure from the paper listed below, 
along with the cell parameters refined from the powder pattern of R040035
      Graf D L
      American Mineralogist 46 (1961) 1283-1316
      Crystallographic tables for the rhombohedral carbonates

      CELL PARAMETERS:   4.6594  4.6594 15.0720   90.000   90.000  120.000
      SPACE GROUP: R-3c      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Zn     0.00000   0.00000   0.00000     1.000     0.700
            C      0.00000   0.00000   0.25000     1.000     0.300
            O      0.27640   0.00000   0.25000     1.000     1.000

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    5.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  3 +/-  3 +/- 13
            MAX. ABS. INTENSITY / VOLUME**2:      62.68353590    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                25.03         51.10        3.5573    0   1   2
                32.51        100.00        2.7540    1   0   4
                38.65         26.10        2.3297    1   1   0
                42.79         12.68        2.1135    1   1   3
                46.60         21.96        1.9489    2   0   2
                51.37         13.05        1.7787    0   2   4
                53.66         31.39        1.7082    1   1   6
                53.69         19.61        1.7071    0   1   8
                61.07          1.26        1.5174    2   1   1
                62.09         14.83        1.4948    1   2   2
                66.09         12.23        1.4137    2   1   4
                66.19          3.48        1.4119    1   0  10
                68.09          5.04        1.3770    2   0   8
                69.07          1.61        1.3598    1   1   9
                69.94         10.41        1.3451    3   0   0
                75.73          3.25        1.2560    0   0  12
                79.35          3.37        1.2075    0   2  10
                81.13          6.20        1.1854    1   2   8
                88.42          3.98        1.1056    1   1  12
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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.