Quartz
Levien L, Prewitt C T, Weidner D J
American Mineralogist 65 (1980) 920-930
Structure and elastic properties of quartz at pressure
P = 20.7 kbar
_database_code_amcsd 0000790
4.8362 4.8362 5.3439 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   .4630     0     0  .0070  .0057  .0035  .0029  .0002  .0004
O    .4111 .2795 .1095  .0148  .0108  .0076  .0075 -.0034 -.0029