Cristobalite
Downs R T, Palmer D C
American Mineralogist 79 (1994) 9-14
The pressure behavior of alpha cristobalite
P = 0.73 GPa
4.9028 4.9028 6.7782 90 90 90 P4_12_12
atom     x     y     z Biso
Si   .3086 .3086     0  .63
O    .2364 .1198 .1870 1.07