Gillespite Hazen R M, Burnham C W American Mineralogist 59 (1974) 1166-1176 The crystal structures of gillespite I and II: A structure determination at high pressure P = 26 kbar, known as gillespite II 7.349 7.515 7.894 90 90 90 P2_12_12 atom x y z Biso Ba 0 0 .000 3.0 Fe 0 .5 .185 1.6 SiA .680 .215 .330 1.5 SiB .270 .190 .290 1.4 O1 .255 .265 .48 5.0 O2A .480 .215 .245 2.9 O2B .245 .978 .28 13.3 O3A .230 .635 .21 12.1 O3B .145 .280 .155 1.9