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 = 6.14 GPa, (Mg1.54Li.23Sc.23)Si2O6 _database_code_amcsd 0002097 9.0548 8.7120 5.1209 90 90 90 *P2_1cn 0 .25 0 atom x y z occ Biso Mg1 0 .0979 .7133 .77 .51 Sc1 0 .0979 .7133 .23 .51 Mg2 .0104 .2652 .2116 .77 .65 Li2 .0104 .2652 .2116 .23 .65 SiA .7022 .9103 .8608 .40 SiB .3002 .0880 .0688 .36 O1A .8805 .9094 .8741 .40 O1B .1243 .0846 .0557 .46 O2A .6244 .7596 .9598 .39 O2B .3757 .2497 .1063 .76 O3A .6468 .9512 .5615 .77 O3B .3615 .9617 .2758 .27