data_global _chemical_name_mineral 'Protopyroxene' loop_ _publ_author_name 'Yang H' 'Finger L W' 'Conrad P G' 'Prewitt C T' 'Hazen R M' _journal_name_full 'American Mineralogist' _journal_volume 84 _journal_year 1999 _journal_page_first 245 _journal_page_last 256 _publ_section_title ; 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 _chemical_formula_sum '(Mg1.54 Sc.23) Li.23 Si2 O6' _cell_length_a 9.2351 _cell_length_b 8.7310 _cell_length_c 5.3216 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 429.089 _exptl_crystal_density_diffrn 3.120 _symmetry_space_group_name_H-M 'P b c n' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '1/2+x,1/2+y,1/2-z' '1/2-x,1/2-y,1/2+z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Mg1 0.00000 0.09790 0.75000 0.77000 0.00697 Sc1 0.00000 0.09790 0.75000 0.23000 0.00697 Mg2 0.00000 0.26540 0.25000 0.77000 0.00887 Li2 0.00000 0.26540 0.25000 0.23000 0.00887 SiA 0.29300 0.09070 0.07380 1.00000 0.00608 O1A 0.11910 0.09210 0.08070 1.00000 0.00646 O2A 0.37440 0.25100 0.07110 1.00000 0.00963 O3A 0.35030 0.98130 0.30480 1.00000 0.00785