Quartz
Levien L, Prewitt C T, Weidner D J
American Mineralogist 65 (1980) 920-930
Structure and elastic properties of quartz at pressure
P = 1 atm
_database_code_amcsd 0000789
4.916 4.916 5.4054 90 90 120 *P3_221
0 0 .666666667
atom     x     y     z B(1,1) B(2,2) B(3,3) B(1,2)  B(1,3)  B(2,3)
Si   .4697     0     0  .0093  .0078  .0049  .0039 -.00001 -.00002
O    .4135 .2669 .1191  .0190  .0144  .0083  .0106 -.00250  -.0035