Protopyroxene Yang H, Finger L W, Conrad P G, Prewitt C T, Hazen R M American Mineralogist 84 (1999) 245-256 A new pyroxene structure at high pressure: Single-crystal X-ray and Raman study of the Pbcn - P2_1cn phase transition in protopyroxene Sample at P = 1.11 GPa, (Mg1.54Li.23Sc.23)Si2O6 _database_code_amcsd 0002093 9.2351 8.7310 5.3216 90 90 90 Pbcn atom x y z occ Biso Mg1 0 .0979 .75 .77 .55 Sc1 0 .0979 .75 .23 .55 Mg2 0 .2654 .25 .77 .70 Li2 0 .2654 .25 .23 .70 SiA .2930 .0907 .0738 .48 O1A .1191 .0921 .0807 .51 O2A .3744 .2510 .0711 .76 O3A .3503 .9813 .3048 .62