Alstonite
      Bindi L, Roberts A C, Biagioni C
      Mineralogical Magazine 84 (2020) 699-704
      The crystal structure of alstonite, BaCa(CO3)2: an extraordinary example
      of 'hidden' complex twinning in large single crystals
      Locality: Fallowfield mine, Northumberland, England
      _database_code_amcsd 0020914

      CELL PARAMETERS:   17.4360  17.4360   6.1295   90.000   90.000  120.000
      SPACE GROUP: P31m      
      X-RAY WAVELENGTH:     1.541838
      Cell Volume:   1613.799
      Density (g/cm3):      3.672
      MAX. ABS. INTENSITY / VOLUME**2:      69.34515069    
      RIR:      6.149
      RIR based on corundum from Acta Crystallographica A38 (1982) 733-739
               2-THETA      INTENSITY    D-SPACING   H   K   L   Multiplicity
                10.15          1.40        8.7180    1   1   0         3
                14.45          4.42        6.1295    0   0   1         1
                15.53          6.10        5.7073    2   1   0         6
                15.60         12.71        5.6794    1   0   1         6
                20.37          7.87        4.3590    2   2   0         3
                21.21          3.72        4.1880    3   1   0         6
                22.86          1.16        3.8899    3   0   1         6
                25.07         48.11        3.5523    4  -2   1         3
                25.07         51.89        3.5523    2   2   1         3
                25.72          3.38        3.4642    3   2   0         6
                25.76          1.92        3.4579    4  -1   1         6
                25.76          1.94        3.4579    3   1   1         6
                29.14          7.69        3.0647    0   0   2         1
                31.50          2.34        2.8397    2   0   2         6
                33.18          1.67        2.7001    2   1   2         6
                33.18          1.60        2.7001    3  -1   2         6
                34.67          1.46        2.5870    4   2   1         6
                34.67          1.82        2.5870    6  -2   1         6
                35.68         22.72        2.5167    6   0   0         6
                35.82         12.56        2.5071    2   2   2         3
                35.82         16.74        2.5071    4  -2   2         3
                36.18          1.07        2.4824    4   3   0         6
                36.22          1.06        2.4801    5   1   1         6
                36.22          1.06        2.4801    6  -1   1         6
                36.32          1.15        2.4732    3   1   2         6
                36.32          1.17        2.4732    4  -1   2         6
                38.68          2.89        2.3281    6   0   1         6
                39.25          1.91        2.2954    5  -2   2         6
                39.25          1.94        2.2954    3   2   2         6
                41.43          7.63        2.1795    4   4   0         3
                41.88          2.18        2.1571    5   3   0         6
                41.91          1.50        2.1556    7  -1   1         6
                41.91          1.43        2.1556    6   1   1         6
                43.20          1.03        2.0940    6   2   0         6
                44.10         12.78        2.0535    8  -4   1         3
                44.10         14.01        2.0535    4   4   1         3
                44.53          1.51        2.0348    7   0   1         6
                45.79          1.06        1.9816    6   2   1         6
                46.70         21.46        1.9449    6   0   2         6
                47.00          1.27        1.9334    5   4   0         6
                49.25          8.32        1.8500    2   2   3         3
                49.25          7.70        1.8500    4  -2   3         3
                51.45          1.77        1.7762    8  -4   2         3
                51.45          1.31        1.7762    4   4   2         3
                55.80          2.32        1.6475    8   2   0         6
                57.96          5.62        1.5911   10  -2   1         6
                57.96          5.81        1.5911    8   2   1         6
                60.41          1.51        1.5324    0   0   4         1
                62.29          1.47        1.4906    8  -4   3         3
                62.29          1.69        1.4906    4   4   3         3
                64.09          2.45        1.4530    6   6   0         3
                64.18          2.42        1.4512   10  -2   2         6
                64.18          2.09        1.4512    8   2   2         6
                64.45          1.27        1.4456    2   2   4         3
                71.91          1.77        1.3129   12  -6   2         3
                71.91          1.91        1.3129    6   6   2         3
                72.17          4.19        1.3088    6   0   4         6
                73.90          3.17        1.2825   10  -2   3         6
                73.90          3.19        1.2825    8   2   3         6
                75.56          2.76        1.2583   12   0   0         6
                81.58          1.14        1.1801    4  -2   5         3
                81.58          1.00        1.1801    2   2   5         3
                82.95          1.15        1.1640   12   0   2         6
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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.