Institute of Experimental Mineralogy
                 Russian Academy of Sciences
     -------------------------------------------------
           142432, Chernogolovka, Moscow district
             A.V. Chichagov  +7(496)52-22320

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          ***      W W W - X R A Y P O L       ***
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TRIDYMITE

9, at 653' K, f-silica

SiO(2)


Orthorhombic  C 222(1)  Z = 8

R =0.118          NR =322

10 .12 .1997

Ref.Str.:

         Kihara K., Matsumoto T., Imamura M. (1986)

         * Z. Kristallogr., 177, 27-38

Reserv:

         N.A.D.

                   Initial data from BDM-file 

   Lattice parameters (cub. angs.,degr.):

             a =   8.743    alpha =   90.0 
             b =   5.046    beta  =   90.0 
             c =   8.254    gamma =   90.0 

    Unit cell volume (cub. angs.) =   364.14

    Molar volume ( cub.cm/mol.) =    27.42

  Co-ordinates, thermal parameters, occupation for atomic positions:

NoP   x/a     y/b     z/c    B(j)   atom  / occupation

   1 0.1686  0.5222  0.1882   0.0    Si    = 1.00
   2 0.3268  0.0     0.5      0.0    O     = 1.00
   3 0.0     0.5401  0.25     0.0    O     = 1.00
   4 0.2554  0.2853  0.263    0.0    O     = 1.00


  Co-ordinates for all atomic positions :

   No       NoP      x/a        y/b       z/c 

     1       1     0.1686     0.5222     0.1882
     2       2     0.3268     0.0        0.5   
     3       3     0.0        0.5401     0.25  
     4       4     0.2554     0.2853     0.263 
     5       1     0.8314     0.4778     0.6882
     6       2     0.6732     0.0        0.0   
     7       3     0.0        0.4599     0.75  
     8       4     0.7446     0.7147     0.763 
     9       1     0.8314     0.5222     0.3118
    10       4     0.7446     0.2853     0.237 
    11       1     0.1686     0.4778     0.8118
    12       4     0.2554     0.7147     0.737 
    13       1     0.3314     0.9778     0.6882
    14       2     0.1732     0.5        0.0   
    15       3     0.5        0.9599     0.75  
    16       4     0.2446     0.2147     0.763 
    17       1     0.6686     0.0222     0.1882
    18       2     0.8268     0.5        0.5   
    19       3     0.5        0.0401     0.25  
    20       4     0.7554     0.7853     0.263 
    21       1     0.6686     0.9778     0.8118
    22       4     0.7554     0.2147     0.737 
    23       1     0.3314     0.0222     0.3118
    24       4     0.2446     0.7853     0.237 


X-ray density (g/cm cub.)   =      2.19

MU (1/cm) =      75.491    Mass attenuation coefficient (cm**2/g) =     34.452

 Selected interatomic distances (cation-anion,anion-anion):

 NoP    Atom              Rad.sph.      C.N.    Distance     NoP N.
                           (angs.)               (angs.)

    1    Si                  2.1          4
                                                 1.5624       3
                                                 1.5447       4
                                                 1.558        2
                                                 1.5383       4
    2    O                   3.264        6
                                                 2.5078       4
                                                 2.5078       4
                                                 2.5675       3
                                                 2.5303       4
                                                 2.5675       3
                                                 2.5303       4
    3    O                   3.264        6
                                                 2.5789       4
                                                 2.5789       4
                                                 2.5675       2
                                                 2.5675       2
                                                 2.473        4
                                                 2.473        4
    4    O                   3.264        6
                                                 2.5078       2
                                                 2.5789       3
                                                 2.5303       2
                                                 2.473        3
                                                 2.5339       4
                                                 2.5339       4

  X-ray diffraction powder data (II),  X-Ray W.L. =   1.54056(angs.):

  No   H   K   L   Theta 2*Theta    S       LPG   MF        F          I int.
                    ( degree )                                         *100

    1   2   0   0 10.149  20.298   0.114   61.5     2       94.3      824.8
    2   1   1   0 10.151  20.303   0.114   61.47    4       86.6     1392.1
    3   0   0   2 10.757  21.514   0.121   54.51    2      122.4     1232.3
    4   2   0   1 11.501  23.003   0.129   47.42    4       52.7      398.0
    5   1   1   1 11.504  23.008   0.129   47.4     8       55.5      880.0
    6   2   0   2 14.873  29.746   0.167   27.54    4       41.6      143.5
    7   1   1   2 14.875  29.75    0.167   27.54    8       44.3      325.8
    8   3   1   0 17.772  35.543   0.198   18.73    4       78.5      348.0
    9   0   2   0 17.776  35.553   0.198   18.72    2       78.3      172.9
   10   3   1   1 18.613  37.226   0.207   16.93    8        9.4        9.1
   11   0   2   1 18.617  37.235   0.207   16.92    4       11.7        7.0
   12   2   0   3 19.317  38.635   0.215   15.59    4       43.6       89.2
   13   1   1   3 19.319  38.638   0.215   15.59    8       40.8      156.8
   14   4   0   0 20.635  41.27    0.229   13.46    2       20.1        8.2
   15   2   2   0 20.64   41.281   0.229   13.46    4        6.0        1.5
   16   3   1   2 20.963  41.926   0.232   13.0     8       13.6       14.5
   17   0   2   2 20.967  41.935   0.232   12.99    4       12.3        5.9
   18   4   0   1 21.38   42.761   0.237   12.44    4       44.5       74.4
   19   2   2   1 21.386  42.772   0.237   12.43    8       43.2      139.9
   20   0   0   4 21.919  43.837   0.242   11.76    2       78.8      110.3
   21   4   0   2 23.502  47.004   0.259   10.05    4       39.0       46.1
   22   2   2   2 23.507  47.015   0.259   10.04    8       37.1       83.2
   23   2   0   4 24.38   48.76    0.268    9.24    4       27.4       21.0
   24   1   1   4 24.381  48.762   0.268    9.24    8       33.4       62.1
   25   3   1   3 24.467  48.935   0.269    9.17    8        3.4        0.6
   26   0   2   3 24.471  48.942   0.269    9.17    4        1.3        0.0
   27   4   0   3 26.749  53.498   0.292    7.48    4       41.3       38.6
   28   2   2   3 26.754  53.507   0.292    7.48    8       41.6       78.1
   29   5   1   0 27.789  55.577   0.303    6.86    4       62.6       81.2
   30   4   2   0 27.792  55.584   0.303    6.86    4       50.6       52.9
   31   1   3   0 27.798  55.596   0.303    6.86    4       50.5       52.8
   32   5   1   1 28.389  56.779   0.309    6.54    8       36.4       52.3
   33   4   2   1 28.393  56.785   0.309    6.54    8       39.0       59.9
   34   1   3   1 28.398  56.797   0.309    6.53    8       42.6       71.6
   35   3   1   4 28.828  57.657   0.313    6.31    8       10.3        4.0
   36   0   2   4 28.832  57.663   0.313    6.31    4        3.7        0.3
   37   2   0   5 29.919  59.838   0.324    5.81    4       65.9       76.0
   38   1   1   5 29.92   59.84    0.324    5.81    8       64.0      143.6
   39   5   1   2 30.145  60.289   0.326    5.71    8       29.1       29.2
   40   4   2   2 30.148  60.296   0.326    5.71    8       30.8       32.7
   41   1   3   2 30.153  60.307   0.326    5.71    8       28.4       27.9
   42   4   0   4 30.888  61.776   0.333    5.41    4       37.1       22.5
   43   2   2   4 30.892  61.784   0.333    5.41    8       33.1       35.7
   44   6   0   0 31.912  63.824   0.343    5.04    2       64.2       31.3
   45   3   3   0 31.921  63.843   0.343    5.03    4       64.3       62.8
   46   6   0   1 32.465  64.931   0.348    4.85    4        5.7        0.5
   47   3   3   1 32.475  64.949   0.349    4.85    8       12.6        4.6
   48   5   1   3 32.944  65.887   0.353    4.7     8       40.4       46.3
   49   4   2   3 32.947  65.894   0.353    4.7     8       36.7       38.3
   50   1   3   3 32.952  65.904   0.353    4.7     8       40.7       46.9
   51   3   1   5 33.888  67.776   0.362    4.43    8        4.3        0.5
   52   0   2   5 33.891  67.782   0.362    4.43    4       10.4        1.5
   53   0   0   6 34.051  68.102   0.363    4.39    2       19.1        2.4
   54   6   0   2 34.097  68.194   0.364    4.37    4       18.7        4.6
   55   3   3   2 34.106  68.212   0.364    4.37    8       19.3        9.8
   56   4   0   5 35.784  71.569   0.38     3.97    4       64.4       49.6
   57   2   2   5 35.788  71.577   0.38     3.96    8       60.2       86.8
   58   2   0   6 35.945  71.889   0.381    3.93    4       19.5        4.5
   59   1   1   6 35.946  71.891   0.381    3.93    8       22.3       11.7
   60   5   1   4 36.673  73.345   0.388    3.78    8       20.4        9.5
   61   4   2   4 36.676  73.351   0.388    3.78    8       21.0       10.1
   62   1   3   4 36.68   73.361   0.388    3.78    8       22.1       11.1
   63   6   0   3 36.739  73.479   0.388    3.77    4        2.2        0.1
   64   3   3   3 36.748  73.496   0.388    3.77    8        4.2        0.4
   65   6   2   0 37.622  75.243   0.396    3.61    4      102.2      113.8
   66   0   4   0 37.633  75.267   0.396    3.61    2       85.5       39.7
   67   6   2   1 38.137  76.273   0.401    3.52    8       31.6       21.2
   68   0   4   1 38.148  76.296   0.401    3.52    4       58.4       36.2
   69   7   1   0 39.444  78.889   0.412    3.33    4       40.2       16.2
   70   5   3   0 39.452  78.904   0.412    3.33    4       48.6       23.7
   71   2   4   0 39.459  78.917   0.413    3.33    4       41.3       17.1
   72   3   1   6 39.622  79.244   0.414    3.3     8       64.4       82.8
   73   0   2   6 39.625  79.25    0.414    3.3     4       59.0       34.7
   74   6   2   2 39.668  79.337   0.414    3.3     8       59.5       70.5
   75   0   4   2 39.68   79.359   0.414    3.3     4       44.6       19.8
   76   7   1   1 39.952  79.904   0.417    3.26    8       31.6       19.7
   77   5   3   1 39.96   79.919   0.417    3.26    8       29.8       17.4
   78   2   4   1 39.966  79.933   0.417    3.26    8       34.5       23.4
   79   6   0   4 40.326  80.651   0.42     3.21    4        2.3        0.1
   80   3   3   4 40.334  80.668   0.42     3.21    8        7.3        1.0
   81   5   1   5 41.27   82.54    0.428    3.11    8       54.9       56.6
   82   4   2   5 41.273  82.545   0.428    3.11    8       55.4       57.5
   83   1   3   5 41.277  82.555   0.428    3.11    8       58.4       64.0
   84   4   0   6 41.422  82.844   0.429    3.09    4       53.1       26.3
   85   2   2   6 41.426  82.852   0.429    3.09    8       54.9       56.3
   86   7   1   2 41.466  82.932   0.43     3.09    8       26.7       13.3
   87   5   3   2 41.474  82.947   0.43     3.09    8       28.8       15.5
   88   2   4   2 41.48   82.961   0.43     3.09    8       26.9       13.5
   89   6   2   3 42.189  84.379   0.436    3.02    8       20.6        7.7
   90   0   4   3 42.201  84.401   0.436    3.02    4       38.0       13.2
   91   2   0   7 42.579  85.157   0.439    2.99    4       11.6        1.2
   92   1   1   7 42.58   85.159   0.439    2.99    8        7.7        1.1
   93   7   1   3 43.97   87.94    0.451    2.89    8       36.7       23.5
   94   5   3   3 43.977  87.955   0.451    2.89    8       29.5       15.2
   95   2   4   3 43.984  87.968   0.451    2.89    8       31.4       17.2
   96   8   0   0 44.815  89.63    0.458    2.84    2        9.3        0.4
   97   4   4   0 44.83   89.66    0.458    2.84    4        6.4        0.3
   98   6   0   5 44.837  89.674   0.458    2.84    4        8.0        0.5
   99   3   3   5 44.846  89.691   0.458    2.84    8       18.8        6.0


  X-ray diffraction powder data (I)...X-Ray wave length =  1.54056 (angs.):

  No   H   K   L   Theta 2*Theta    d           I int   I int.n.  I p.h.n.   H(Si)
                    ( degree )   (angstrem)     *100                         *100

    1   1   1   0  10.151  20.303  4.37035     2216.9    100.0    100.0     5.6
    2   0   0   2  10.757  21.514  4.127       1232.3     55.6     55.5     5.6
    3   1   1   1  11.504  23.008  3.86235     1278.0     57.6     57.5     5.6
    4   1   1   2  14.875  29.75   3.00057      469.4     21.2     21.0     5.6
    5   3   1   0  17.772  35.543  2.52366      520.9     23.5     23.2     5.7
    6   1   1   3  19.319  38.638  2.32836      246.0     11.1     10.9     5.7
    7   2   2   1  21.386  42.772  2.1124       214.2      9.7      9.5     5.7
    8   0   0   4  21.919  43.837  2.0635       110.3      5.0      4.9     5.7
    9   2   2   2  23.507  47.015  1.93117      129.2      5.8      5.7     5.7
   10   1   1   4  24.381  48.762  1.86596       83.0      3.7      3.6     5.7
   11   2   2   3  26.754  53.507  1.71115      116.7      5.3      5.1     5.8
   12   5   1   0  27.789  55.577  1.65221      186.9      8.4      8.1     5.8
   13   1   3   1  28.398  56.797  1.6196       183.8      8.3      8.0     5.8
   14   1   1   5  29.92   59.84   1.5443       219.6      9.9      9.5     5.8
   15   4   2   2  30.148  60.296  1.53371       89.8      4.0      3.9     5.8
   16   2   2   4  30.892  61.784  1.50029       58.2      2.6      2.5     5.8
   17   3   3   0  31.921  63.843  1.45678       94.1      4.2      4.1     5.9
   18   1   3   3  32.952  65.904  1.41612      131.4      5.9      5.6     5.9
   19   2   2   5  35.788  71.577  1.31718      136.3      6.2      5.8     5.9
   20   1   3   4  36.68   73.361  1.28949       30.7      1.4      1.3     6.0
   21   6   2   0  37.622  75.243  1.26183      153.5      6.9      6.5     6.0
   22   0   4   1  38.148  76.296  1.24702       57.4      2.6      2.4     6.0
   23   2   4   0  39.459  78.917  1.21204       57.0      2.6      2.4     6.0
   24   3   1   6  39.622  79.244  1.20787      117.5      5.3      4.9     6.0
   25   6   2   2  39.668  79.337  1.20669       90.3      4.1      3.8     6.0
   26   2   4   1  39.966  79.933  1.19918       60.5      2.7      2.5     6.0
   27   1   3   5  41.277  82.555  1.16761      178.2      8.0      7.4     6.1
   28   2   2   6  41.426  82.852  1.16418       82.6      3.7      3.4     6.1
   29   2   4   2  41.48   82.961  1.16293       42.3      1.9      1.8     6.1
   30   7   1   3  43.97   87.94   1.10947       55.8      2.5      2.3     6.2

Reference:
Chichagov A.V. et al.
Information-Calculating System on Crystal Structure Data of Minerals
(MINCRYST)
- Kristallographiya, v.35, n.3, 1990, p.610-616 (in Russian)