Genthelvite
      Diffraction data computed using the structure from the paper listed below, 
      along with the cell parameters refined from single crystal data of R080134 
            Hassan I, Grundy H D
      American Mineralogist 70 (1985) 186-192
      The crystal structures of helvite group minerals, (MnFeZn)8(Be6Si6O24)S2

      CELL PARAMETERS:   8.1500  8.1500  8.1500   90.000   90.000   90.000
      SPACE GROUP: P-43n     

           ATOM        X         Y         Z     OCCUPANCY  ISO(B)
            Zn     0.16740   0.16740   0.16740     1.000     0.474
            O      0.13820   0.13850   0.40290     1.000     0.387
            Be     0.25000   0.00000   0.50000     1.000     0.453
            Si     0.25000   0.50000   0.00000     1.000     0.200
            S      0.00000   0.00000   0.00000     1.000     0.537

            X-RAY WAVELENGTHS:   1.540562  1.544390
            BOUNDS ON TWO THETA:    5.0  90.0
            LIMITS IMPOSED ON THE INDICES ARE:  +/-  7 +/-  7 +/-  7
            MAX. ABS. INTENSITY / VOLUME**2:      68.71613553    
            The INTENSITY cut off value is   1.00

               2-THETA          INTENSITY       D-SPACING   H   K   L
            15.36 / 15.40     1.52 /  0.76       5.7629     1   1   0
            21.79 / 21.85     4.58 /  2.29       4.0750     2   0   0
            24.40 / 24.46     5.80 /  2.90       3.6448     2   1   0
            26.77 / 26.84   100.00 / 50.00       3.3272     2   1   1
            31.01 / 31.09     3.15 /  1.57       2.8815     2   2   0
            34.78 / 34.87    16.00 /  8.00       2.5773     3   1   0
            38.22 / 38.32     3.12 /  1.56       2.3527     2   2   2
            39.85 / 39.95     1.48 /  0.74       2.2604     3   2   0
            41.42 / 41.53    19.37 /  9.68       2.1782     3   2   1
            44.43 / 44.54     3.63 /  1.81       2.0375     4   0   0
            47.28 / 47.40    22.23 / 11.12       1.9210     4   1   1
            47.28 / 47.40    19.19 /  9.60       1.9210     3   3   0
            50.01 / 50.14     6.34 /  3.17       1.8224     4   2   0
            51.33 / 51.47     1.38 /  0.69       1.7785     4   2   1
            52.63 / 52.77     1.63 /  0.81       1.7376     3   3   2
            55.16 / 55.31     9.24 /  4.62       1.6636     4   2   2
            57.62 / 57.78     1.19 /  0.59       1.5983     4   3   1
            57.62 / 57.78     2.62 /  1.31       1.5983     5   1   0
            62.35 / 62.52    10.01 /  5.01       1.4880     5   2   1
            64.64 / 64.82     8.12 /  4.06       1.4407     4   4   0
            66.89 / 67.07     3.11 /  1.56       1.3977     4   3   3
            66.89 / 67.07     4.64 /  2.32       1.3977     5   3   0
            69.09 / 69.29     5.15 /  2.58       1.3583     4   4   2
            69.09 / 69.29     3.82 /  1.91       1.3583     6   0   0
            71.27 / 71.47     5.34 /  2.67       1.3221     5   3   2
            73.42 / 73.63     1.86 /  0.93       1.2886     6   2   0
            75.54 / 75.76     9.27 /  4.64       1.2576     5   4   1
            83.87 / 84.13     1.32 /  0.66       1.1526     5   4   3
            87.98 / 88.25     1.07 /  0.54       1.1091     5   5   2
            87.98 / 88.25     3.08 /  1.54       1.1091     7   2   1
            87.98 / 88.25     5.67 /  2.83       1.1091     6   3   3
================================================================================
       XPOW Copyright 1993 Bob Downs, Ranjini Swaminathan and Kurt Bartelmehs
  For reference, see Downs et al. (1993) American Mineralogist 78, 1104-1107.