data_global
_chemical_name_mineral 'Cummingtonite'
loop_
_publ_author_name
'Yang H'
'Hazen R M'
'Prewitt C T'
'Finger L W'
'Lu R'
'Hemley R J'
_journal_name_full 'American Mineralogist'
_journal_volume 83 
_journal_year 1998
_journal_page_first 288
_journal_page_last 299
_publ_section_title
;
 High-pressure single-crystal X-ray diffraction and infrared spectroscopic
 studies of the C2/m-P2_1/m phase transition in cummingtonite
 Sample: P = 1.10 GPa
;
_database_code_amcsd 0001972
_chemical_formula_sum 'Fe3.471 Mg3.445 Al.008 Ca.076 Si8 O24'
_cell_length_a 9.4638
_cell_length_b 18.1333
_cell_length_c 5.3022
_cell_angle_alpha 90
_cell_angle_beta 102.372
_cell_angle_gamma 90
_cell_volume 888.779
_exptl_crystal_density_diffrn      3.324
_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
Fe1   0.00000   0.08690   0.50000   0.40500   0.00963
Mg1   0.00000   0.08690   0.50000   0.59500   0.00963
Fe2   0.00000   0.17700   0.00000   0.20700   0.00823
Mg2   0.00000   0.17700   0.00000   0.78900   0.00823
Al2   0.00000   0.17700   0.00000   0.00400   0.00823
Fe3   0.00000   0.00000   0.00000   0.39300   0.00899
Mg3   0.00000   0.00000   0.00000   0.60700   0.00899
Fe4   0.00000   0.25910   0.50000   0.92700   0.01140
Mg4   0.00000   0.25910   0.50000   0.03500   0.01140
Ca4   0.00000   0.25910   0.50000   0.03800   0.01140
Si1   0.28900   0.08400   0.27640   1.00000   0.00773
Si2   0.29790   0.16860   0.78230   1.00000   0.00861
O1   0.11790   0.08710   0.21050   1.00000   0.00785
O2   0.12760   0.17270   0.72200   1.00000   0.01051
O3   0.11740   0.00000   0.70790   1.00000   0.01127
O4   0.38010   0.24540   0.76630   1.00000   0.01368
O5   0.35340   0.13140   0.06770   1.00000   0.01051
O6   0.35300   0.11820   0.56250   1.00000   0.01482
O7   0.34470   0.00000   0.27090   1.00000   0.00912