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 = 7.93 GPa, (Mg1.54Li.23Sc.23)Si2O6
;
_database_code_amcsd 0002098
_chemical_formula_sum '(Mg1.54 Sc.23) Li.23 Si2 O6'
_cell_length_a 9.0219
_cell_length_b 8.6711
_cell_length_c 5.0898
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 398.174
_exptl_crystal_density_diffrn      3.362
_symmetry_space_group_name_H-M 'P 21 c n'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,-y,1/2+z'
  '1/2+x,1/2+y,1/2-z'
  '1/2+x,1/2-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   0.09770   0.71050   0.77000   0.00735
Sc1   0.00000   0.09770   0.71050   0.23000   0.00735
Mg2   0.01200   0.26660   0.21030   0.77000   0.00937
Li2   0.01200   0.26660   0.21030   0.23000   0.00937
SiA   0.70210   0.91040   0.85670   1.00000   0.00545
SiB   0.30010   0.08860   0.06820   1.00000   0.00570
O1A   0.88060   0.90930   0.87180   1.00000   0.00405
O1B   0.12340   0.08410   0.05470   1.00000   0.00583
O2A   0.62410   0.75940   0.96140   1.00000   0.00608
O2B   0.37580   0.24890   0.11040   1.00000   0.00861
O3A   0.64360   0.94780   0.55480   1.00000   0.00709
O3B   0.36170   0.95930   0.27410   1.00000   0.00595