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
BaCrSi4O10
7.5314 7.5314 16.0518 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)
Ba      .25    .75      0 .00651 .00651 .00117       0       0       0
Cr      .25    .25 .09181 .00419 .00419 .00170       0       0       0
Si   .51961 .93512 .15441 .00491 .00493 .00112  .00032  .00007 -.00008
O1   .47275 .97275    .25 .01530 .01530 .00126 -.00202  .00140 -.00140
O2   .72301 .99639 .13722 .00444 .00951 .00203 -.00074 -.00007  .00067
O3   .39096 .02503 .08973 .00701 .00544 .00255  .00122 -.00151 -.00066