Cristobalite
Downs R T, Palmer D C
American Mineralogist 79 (1994) 9-14
The pressure behavior of alpha cristobalite
P = 0.19 GPa
4.9501 4.9501 6.8760 90 90 90 P4_12_12
atom     x     y     z Biso
Si   .3027 .3027     0  .80
O    .2388 .1086 .1817 1.22