Boltwoodite
Diffraction data computed using the structure from the paper listed below, 
along with the cell parameters refined from the powder pattern of R060753
      Stohl F V, Smith D K
      American Mineralogist 66 (1981) 610-625
      The crystal chemistry of the uranyl silicate minerals

      CELL PARAMETERS:   7.0580  7.0450  6.6290   90.000  105.380   90.000
      SPACE GROUP: P2_1      

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            U      0.02520   0.25000   0.13850     1.000    10.900
            K      0.54100   0.54800   0.15000     1.000    34.400
            Si     0.93300   0.25000   0.63000     1.000    70.900
            O      0.29000   0.25000   0.14000     1.000    70.600
            O      0.22700   0.75000   0.88000     1.000    53.900
            O      0.02200  -0.07900   0.19000     1.000    44.700
            O     -0.02200   0.07900  -0.19000     1.000    44.700
            O      0.06000   0.25000   0.48000     1.000    40.900
            O      0.29400   0.75000   0.49000     1.000     3.700
            Wa     0.40000   0.41300   0.68000     1.000    92.300

            X-RAY WAVELENGTH:     1.541838
            BOUNDS ON TWO THETA:    0.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  6 +/-  6 +/-  5
            MAX. ABS. INTENSITY / VOLUME**2:      90.58223985    
            The INTENSITY cut off value is   1.00

               2-THETA      INTENSITY    D-SPACING   H   K   L
                13.01        100.00        6.8052    1   0   0
                13.86         31.22        6.3916    0   0   1
                16.31         20.73        5.4332   -1   0   1
                18.75         33.73        4.7337    0   1   1
                20.64         16.63        4.3023   -1   1   1
                21.45          4.75        4.1428    1   0   1
                24.93         25.97        3.5711    1   1   1
                25.28         17.47        3.5225    0   2   0
                26.19         14.67        3.4026    2   0   0
                26.20         13.65        3.4009   -2   0   1
                28.53         22.56        3.1283    1   2   0
                28.94          4.10        3.0850    0   2   1
                29.15          1.91        3.0640    2   1   0
                29.16          5.00        3.0627   -2   1   1
                30.24         10.00        2.9557   -1   2   1
                30.35         18.98        2.9455   -1   1   2
                30.72         15.25        2.9104    0   1   2
                33.39          2.88        2.6836    1   2   1
                35.38          5.61        2.5368    2   1   1
                35.41          6.28        2.5347   -2   1   2
                36.39          5.67        2.4690    1   1   2
                36.72          4.70        2.4473    2   2   0
                36.73          5.09        2.4467   -2   2   1
                38.43          1.92        2.3426   -3   0   1
                39.74          2.30        2.2684    3   0   0
                40.89          1.13        2.2070   -1   0   3
                40.94          2.94        2.2043    0   3   1
                41.84          1.16        2.1592    3   1   0
                41.91          1.21        2.1556   -1   3   1
                42.43          1.97        2.1305    0   0   3
                42.94          1.08        2.1060   -1   1   3
                44.30          2.30        2.0445   -3   1   2
                44.34          2.56        2.0429    1   3   1
                45.65          2.10        1.9873    2   1   2
                45.69          1.66        1.9855   -2   1   3
                46.56          1.67        1.9506   -3   2   1
                47.68          1.89        1.9072    3   2   0
                47.74          1.56        1.9050    3   1   1
                47.82          2.24        1.9019   -1   3   2
                48.08          2.00        1.8924    0   3   2
                50.03          1.33        1.8230    0   2   3
                51.41          1.01        1.7773    2   3   1
                51.44          1.11        1.7766   -2   3   2
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.