data_global
_chemical_name_mineral 'Birnessite'
loop_
_publ_author_name
'Post J E'
'Veblen D R'
_journal_name_full 'American Mineralogist'
_journal_volume 75 
_journal_year 1990
_journal_page_first 477
_journal_page_last 489
_publ_section_title
;
 Crystal structure determinations of synthetic sodium, magnesium and potassium
 birnessite using TEM and the Rietveld method
 Sample: K-birn
;
_database_code_amcsd 0001302
_chemical_formula_sum 'Mn O2.7 K.23 H1.4'
_cell_length_a 5.149
_cell_length_b 2.843
_cell_length_c 7.176
_cell_angle_alpha 90
_cell_angle_beta 100.76
_cell_angle_gamma 90
_cell_volume 103.200
_exptl_crystal_density_diffrn      3.493
_symmetry_space_group_name_H-M 'C 1 2/m 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2+y,z'
  'x,-y,z'
  '1/2+x,1/2-y,z'
  '-x,y,-z'
  '1/2-x,1/2+y,-z'
  '-x,-y,-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
Mn   0.00000   0.00000   0.00000   1.00000   0.00633
O1   0.36500   0.00000   0.13600   1.00000   0.01267
K   0.72300   0.00000   0.52200   0.11500   0.01900
Wat2   0.72300   0.00000   0.52200   0.27500   0.01900
Wat3   0.00000   0.00000   0.50000   0.15000   0.01900