Quartz
Levien L, Prewitt C T, Weidner D J
American Mineralogist 65 (1980) 920-930
Structure and elastic properties of quartz at pressure
P = 48.6 kbar
_database_code_amcsd 0000792
4.739 4.739 5.279 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   .4551     0     0 0.0087 0.0070 0.0039 0.0035 -0.0003 -0.0006
O    .4061 .2912 .1012 0.0150 0.0128 0.0065 0.0078 -0.0042 -0.0031