Helvite Diffraction data computed using the structure from the paper listed below, along with the cell parameters refined from the powder pattern R060059 Hassan I, Grundy H D American Mineralogist 70 (1985) 186-192 The crystal structures of helvite group minerals, (MnFeZn)8(Be6Si6O24)S2 CELL PARAMETERS: 8.236000 8.236000 8.236000 90.00000 90.00000 90.00000 SPACE GROUP: P-43n X-RAY WAVELENGTH: 1.541838 2-THETA INTENSITY D-SPACING H K L 21.53 2.03 4.1387 2 0 0 24.10 8.47 3.7018 2 1 0 26.43 100.00 3.3793 2 1 1 30.60 2.58 2.9265 2 2 0 34.31 14.32 2.6176 3 1 0 37.69 4.28 2.3895 2 2 2 39.29 2.11 2.2958 3 2 0 40.83 19.56 2.2122 3 2 1 43.79 2.53 2.0694 4 0 0 46.59 23.52 1.9510 4 1 1 46.59 19.80 1.9510 3 3 0 49.27 5.86 1.8509 4 2 0 50.57 1.94 1.8063 4 2 1 51.84 1.13 1.7648 3 3 2 54.33 8.49 1.6896 4 2 2 56.74 2.54 1.6233 5 1 0 60.23 1.13 1.5371 4 3 2 61.37 5.83 1.5112 5 2 1 63.61 8.50 1.4633 4 4 0 65.80 4.41 1.4196 5 3 0 65.80 2.91 1.4196 4 3 3 67.96 5.26 1.3796 4 4 2 67.96 3.34 1.3796 6 0 0 70.09 6.11 1.3428 5 3 2 72.19 1.40 1.3088 6 2 0 74.26 8.31 1.2772 5 4 1 76.32 1.02 1.2479 6 2 2 82.38 1.10 1.1706 5 4 3 86.37 2.90 1.1264 7 2 1 86.37 4.59 1.1264 6 3 3 86.37 4.59 1.1264 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.