data_Fayalite

_chemical_name_systematic          'Iron silicate - $-alpha'
_chemical_name_mineral             'Fayalite'
_chemical_formula_structural       'Fe2 Si O4'
_chemical_formula_sum              'Fe2 O4 Si'

_publ_section_title                
;
X-ray Determination of Electron Distributions in Forsterite, Fayalite 
and Tephroite
;
loop_
_publ_author_name                  
  'Fujino, K'
  'Sasaki, S'
  'Takeuchi, Y'
  'Sadanaga, R'
_journal_name_full                 'Acta Crystallographica B (24,1968-38,1982)'
_journal_coden_ASTM                ACBCAR
_journal_volume                    37
_journal_year                      1981
_journal_page_first                513
_journal_page_last                 518

_cell_length_a                     4.8195(6)
_cell_length_b                     10.4788(17)
_cell_length_c                     6.0873(8)
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  90
_cell_volume                       307.4
_cell_formula_units_Z              4

_symmetry_space_group_name_H-M     'P b n m'
_symmetry_Int_Tables_number        62
_symmetry_cell_setting             orthorhombic

loop_
_symmetry_equiv_pos_as_xyz         
  'x,y,z'
  '1/2-x,1/2+y,1/2-z'
  '-x,-y,1/2+z'
  '1/2+x,1/2-y,-z'
  '-x,-y,-z'
  '1/2+x,1/2-y,1/2+z'
  'x,y,1/2-z'
  '1/2-x,1/2+y,z'

loop_
_atom_type_symbol
_atom_type_oxidation_number
  Fe2+   2.000
  Si4+   4.000
  O2-   -2.000

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Fe1   Fe2+   4 a 0. 0. 0. 1.  0 d
  Fe2   Fe2+   4 c 0.98598(5) 0.28026(2) 0.25 1.  0 d
  Si1   Si4+   4 c 0.43122(10) 0.09765(5) 0.25 1.  0 d
  O1    O2-    4 c 0.76814(23) 0.09217(12) 0.25 1.  0 d
  O2    O2-    4 c 0.20895(25) 0.45365(11) 0.25 1.  0 d
  O3    O2-    8 d 0.28897(17) 0.16563(9) 0.03643(9) 1.  0 d

_refine_ls_R_factor_all            0.0255