COL  ICSD Collection Code 67689
 DATE Recorded Jan 19, 1994; updated Jun 29, 1998
 NAME Calcium magnesium alumosilicate *
 MINR Akermanite-Gehlenite - synthetic from glas at 1523 K for 2 d
 MINR Melilite
 FORM Ca2 (Mg0.5 Al0.5) (Si1.5 Al0.5 O7)
      = Al Ca2 Mg.5 O7 Si1.5
 FORM Ca2.03 Mg.46 Al.99 Si1.52 O7
 TITL Neutron diffraction study of the akermanite-gehlenite solid 
      solution series
 REF  Physics and Chemistry of Minerals (Germany)
      PCMID 19 (1992) 185-195
 AUT  Swainson I P, Dove˙M˙T, Schmahl˙W˙W, Putnis˙A
 CELL a=7.747 b=7.747 c=5.036 ŕ=90.0 á=90.0 ç=90.0
      V=302.3 Z=2
 SGR  P -4 21 m     (113) - tetragonal
 CLAS -42m  (Hermann-Mauguin) - D2d (Schoenflies)
 PRS  tP24
 ANX  AB2C2X7
 PARM Atom__No OxStat  Wyck ---X--- ---Y--- ---Z---  -SOF-
      Ca     1  2.000    4e  0.3369  0.1631  0.5093
      Al     1  3.000    2a  0.      0.      0.        0.5
      Mg     1  2.000    2a  0.      0.      0.        0.5
      Si     2  4.000    4e  0.1419  0.3581  0.9427    0.75
      Al     2  3.000    4e  0.1419  0.3581  0.9427    0.25
      O      1 -2.000    2c  1/2     0.      0.1782
      O      2 -2.000    4e  0.1423  0.3577  0.2676
      O      3 -2.000    8f  0.085   0.1778  0.798
 WYCK f e3 c a
˙
 TF   Atom   B(1,1)  B(2,2)  B(3,3)  B(1,2)  B(1,3)  B(2,3)
      Ca 1    2.7400  2.7400 -0.0900  0.9600 -0.2100 -0.2100
      Al 1    1.0100  1.0100  0.1800  0.0000  0.0000  0.0000
      Mg 1    1.0100  1.0100  0.1800  0.0000  0.0000  0.0000
      Si 2    1.2900  1.2900 -0.4000 -0.0900 -0.1200 -0.1200
      Al 2    1.2900  1.2900 -0.4000 -0.0900 -0.1200 -0.1200
      O  1    2.6000  2.6000 -0.2600 -1.4700  0.0000  0.0000
      O  2    2.9000  2.9000 -0.2900  0.0000  0.6900  0.6900
      O  3    3.0700  2.2700  0.1600 -0.5100 -0.3700 -0.2400
 REM  TEM 300
 REM  NDP (neutron diffraction from a powder)
 REM  F 50% Akermanite
 RVAL 0.069
 TEST At least one temperature factor is implausible or meaningless but 
      agrees with the value given in the paper. (Code 52)