Ankerite
Diffraction data computed using the structure from the paper listed below,
along with the cell parameters refined from the powder pattern R050197
      Reeder R J, Dollase W A
      American Mineralogist 74 (1989) 1159-1167
      Structural variation in the dolomite-ankerite solid-solution series: An X-ray,
      Mossbauer, and TEM study
      sample AMNH 6376

      CELL PARAMETERS:   4.832821   4.832821   16.20903   90.00000   90.00000   120.0000
      SPACE GROUP: R-3
      X-RAY WAVELENGTH:     1.541838
               2-THETA      INTENSITY    D-SPACING   H   K   L
                16.39          1.91        5.4030    0   0   3
                23.91         13.10        3.7187    0   1   2
                30.69        100.00        2.9113    1   0   4
                33.14          1.55        2.7015    0   0   6
                37.18         14.90        2.4164    1   1   0
                40.88         10.32        2.2059    2  -1   3
                40.88          9.67        2.2059    1   1   3
                44.69         16.09        2.0262    2   0   2
                48.95          6.67        1.8594    0   2   4
                49.97         18.32        1.8237    0   1   8
                50.64          9.11        1.8010    1   1   6
                50.64         14.70        1.8010    2  -1   6
                58.58          2.28        1.5744    2   1   1
                59.49          6.95        1.5526   -1   3   2
                59.49          3.57        1.5526    1   2   2
                61.28          1.34        1.5115    1   0  10
                63.03          4.26        1.4736    3  -1   4
                63.03          3.30        1.4736    2   1   4
                63.90          3.31        1.4556    2   0   8
                64.48          1.69        1.4440    1   1   9
                64.48          1.00        1.4440    2  -1   9
                67.03          8.02        1.3951    3   0   0
                69.54          3.53        1.3508    0   0  12
                73.90          2.94        1.2815    0   2  10
                76.31          1.02        1.2469   -1   3   8
                76.31          2.85        1.2469    1   2   8
                81.59          1.90        1.1790    1   1  12
                85.75          1.21        1.1321    2   1  10
                85.75          1.41        1.1321    3  -1  10
                87.30          1.37        1.1159    1   3   4
                87.30          1.37        1.1159    1   3   4
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.