Gillespite
Miletich R, Allan D R, Angel R J
American Mineralogist 82 (1997) 697-707
The synthetic Cr2+ silicates BaCrSi4O10 and SrCrSi4O10: The missing links in
the gillespite-type ABSi4O10 series
SrCrSi4O10
7.4562 7.4562 15.5414 90 90 90 *P4/ncc
.25 -.25 0
atom      x      y      z B(1,1) B(2,2) B(3,3)  B(1,2)  B(1,3)  B(2,3)
Sr      .25    .75      0 .00518 .00518 .00128       0       0       0
Cr      .25    .25 .08564 .00368 .00368 .00164       0       0       0
Si   .50962 .92707 .15094 .00360 .00428 .00124  .00001  .00010 -.00002
O1   .46361 .96361    .25 .01102 .01102 .00173 -.00131  .00117 -.00117
O2   .71284 .99735 .13192 .00434 .00842 .00186 -.00094 -.00026  .00062
O3   .37015 .01058 .08572 .00460 .00385 .00252  .00130 -.00114  .00051