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 = 1.32 GPa
;
_database_code_amcsd 0001973
_chemical_formula_sum 'Fe3.471 Mg3.445 Al.008 Ca.076 Si8 O24'
_cell_length_a 9.4498
_cell_length_b 18.1083
_cell_length_c 5.2978
_cell_angle_alpha 90
_cell_angle_beta 102.417
_cell_angle_gamma 90
_cell_volume 885.353
_exptl_crystal_density_diffrn      3.337
_symmetry_space_group_name_H-M 'P 1 21/m 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,1/2-y,z'
  '-x,1/2+y,-z'
  '-x,-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  -0.24580   0.33700   0.49380   0.40500   0.00836
Mg1  -0.24580   0.33700   0.49380   0.59500   0.00836
Fe2  -0.25210   0.42680   0.99400   0.20700   0.00925
Mg2  -0.25210   0.42680   0.99400   0.78900   0.00925
Al2  -0.25210   0.42680   0.99400   0.00400   0.00925
Fe3  -0.25160   0.25000   0.98950   0.39300   0.00811
Mg3  -0.25160   0.25000   0.98950   0.60700   0.00811
Fe4  -0.26040   0.50930   0.48410   0.92700   0.00988
Mg4  -0.26040   0.50930   0.48410   0.03500   0.00988
Ca4  -0.26040   0.50930   0.48410   0.03800   0.00988
Si1A   0.04300   0.33640   0.27680   1.00000   0.00760
Si1B   0.53520   0.83150   0.27680   1.00000   0.00646
Si2A   0.05160   0.41980   0.78080   1.00000   0.00823
Si2B   0.54530   0.91750   0.78470   1.00000   0.00937
O1A  -0.13530   0.33950   0.21940   1.00000   0.00925
O1B   0.36830   0.83430   0.20220   1.00000   0.00836
O2A  -0.12790   0.42530   0.71010   1.00000   0.00709
O2B   0.38110   0.91980   0.73150   1.00000   0.00785
O3A  -0.11760   0.25000   0.72160   1.00000   0.00963
O3B   0.35740   0.75000   0.69850   1.00000   0.00836
O4A   0.13270   0.49610   0.77010   1.00000   0.01406
O4B   0.62620   0.99530   0.76390   1.00000   0.01507
O5A   0.10590   0.37740   0.04630   1.00000   0.00874
O5B   0.59760   0.88620   0.08330   1.00000   0.00950
O6A   0.10250   0.37440   0.54890   1.00000   0.01178
O6B   0.60650   0.86150   0.57960   1.00000   0.01368
O7A   0.09090   0.25000   0.28800   1.00000   0.00811
O7B   0.60270   0.75000   0.25260   1.00000   0.00684