data_9009730
_chemical_name 'Akermanite'
loop_
_publ_author_name
'Kusaka K'
'Ohmasa M'
'Hagiya K'
'Iishi K'
'Haga N'
_journal_name_full "Mineralogical Journal"
_journal_volume 20
_journal_year 1998
_journal_page_first 47
_journal_page_last 58
_publ_section_title
;
 On variety of the Ca coordination in the incommensurate structure of
 synthetic iron-bearing akermanite, Ca2(Mg0.55,Fe0.45)Si2O7
 Note: Sample is synthetic, this is the structure obtained from a standard refin
;
_chemical_formula_sum 'Ca2 (Mg.554 Fe.446) Si2 O7'
_cell_length_a 7.8679
_cell_length_b 7.8679
_cell_length_c 5.0144
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 310.411
_symmetry_space_group_name_H-M 'P -4 21 m'
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '1/2-y,1/2-x,z'
  'y,-x,-z'
  '1/2-x,1/2+y,-z'
  '-x,-y,z'
  '1/2+y,1/2+x,z'
  '-y,x,-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_Uiso_or_equiv
Ca   0.33070   0.16930   0.50610   1.00000   0.02424
Mg   0.00000   0.00000   0.00000   0.55400   0.01267
Fe   0.00000   0.00000   0.00000   0.44600   0.01267
Si   0.13840   0.36160   0.93830   1.00000   0.01115
O1   0.00000   0.50000   0.82500   1.00000   0.04445
O2   0.13900   0.36100   0.25700   1.00000   0.02850
O3   0.07950   0.18980   0.78910   1.00000   0.03762