Ankerite
Diffraction data computed using the structure from the paper listed below,
along with the cell parameters refined from the powder pattern R050181
      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:   4.827026   4.827026   16.14751   90.00000   90.00000   120.0000
      SPACE GROUP: R-3
      X-RAY WAVELENGTH:     1.541838
               2-THETA      INTENSITY    D-SPACING   H   K   L
                16.50          1.91        5.3825    0   0   3
                23.99         13.10        3.7122    0   1   2
                30.81        100.00        2.9039    1   0   4
                33.30          1.55        2.6913    0   0   6
                37.26         14.90        2.4135    1   1   0
                40.99         10.32        2.2023    2  -1   3
                40.99          9.67        2.2023    1   1   3
                44.79         16.09        2.0235    2   0   2
                49.08          6.67        1.8561    0   2   4
                50.19         18.32        1.8176    0   1   8
                50.81          9.11        1.7968    1   1   6
                50.81         14.70        1.7968    2  -1   6
                58.70          2.28        1.5725    2   1   1
                59.61          6.95        1.5506   -1   3   2
                59.61          3.57        1.5506    1   2   2
                61.55          1.34        1.5063    1   0  10
                63.18          4.26        1.4713    3  -1   4
                63.18          3.30        1.4713    2   1   4
                64.12          3.31        1.4519    2   0   8
                64.72          1.69        1.4399    1   1   9
                64.72          1.00        1.4399    2  -1   9
                67.16          8.02        1.3934    3   0   0
                69.88          3.53        1.3456    0   0  12
                74.18          2.94        1.2778    0   2  10
                76.54          1.02        1.2442   -1   3   8
                76.54          2.85        1.2442    1   2   8
                81.94          1.90        1.1753    1   1  12
                86.05          1.21        1.1293    2   1  10
                86.05          1.41        1.1293    3  -1  10
                87.50          1.37        1.1144    1   3   4
                87.50          1.37        1.1144    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.