data_global
_chemical_name_mineral 'Cummingtonite'
loop_
_publ_author_name
'Yang H'
'Hirschmann M M'
_journal_name_full 'American Mineralogist'
_journal_volume 80 
_journal_year 1995
_journal_page_first 916
_journal_page_last 922
_publ_section_title
;
 Crystal structure of P2_1/m ferromagnesian amphibole and the role of cation
 ordering and composition in the P2_1/m - C2/m transition in cummingtonite
 Sample: 1c, heat treated at 700 C
;
_database_code_amcsd 0001754
_chemical_formula_sum 'Fe2.473 Mg4.423 Al.014 Ca.1 Si8 O24'
_cell_length_a 9.5057
_cell_length_b 18.1187
_cell_length_c 5.3059
_cell_angle_alpha 90
_cell_angle_beta 102.031
_cell_angle_gamma 90
_cell_volume 893.768
_exptl_crystal_density_diffrn      3.191
_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  -0.24930   0.33690   0.49230   0.25000   0.00852
Mg1  -0.24930   0.33690   0.49230   0.75000   0.00852
Fe2  -0.25010   0.42730   0.99140   0.16300   0.00823
Mg2  -0.25010   0.42730   0.99140   0.83000   0.00823
Al2  -0.25010   0.42730   0.99140   0.00700   0.00823
Fe3  -0.24950   0.25000   0.99330   0.22100   0.00689
Mg3  -0.24950   0.25000   0.99330   0.78900   0.00689
Fe4  -0.25170   0.50890   0.48970   0.71300   0.01160
Mg4  -0.25170   0.50890   0.48970   0.23700   0.01160
Ca4  -0.25170   0.50890   0.48970   0.05000   0.01160
Si1a   0.03860   0.33440   0.26490   1.00000   0.00778
Si2a   0.04610   0.41940   0.77100   1.00000   0.00728
Si1b   0.53680   0.83390   0.28180   1.00000   0.00632
Si2b   0.54910   0.91830   0.78800   1.00000   0.00754
O1a  -0.13540   0.33680   0.20250   1.00000   0.00946
O2a  -0.12750   0.42280   0.70750   1.00000   0.00830
O3a  -0.13620   0.25000   0.70090   1.00000   0.00979
O4a   0.12850   0.49720   0.77740   1.00000   0.01222
O5a   0.10110   0.37510   0.04030   1.00000   0.01360
O6a   0.10360   0.37560   0.53600   1.00000   0.01426
O7a   0.09510   0.25000   0.28650   1.00000   0.01123
O1b   0.36400   0.83710   0.21630   1.00000   0.00806
O2b   0.37400   0.92290   0.72670   1.00000   0.00992
O3b   0.36340   0.75000   0.71600   1.00000   0.01240
O4b   0.63260   0.99370   0.76200   1.00000   0.01106
O5b   0.60040   0.88500   0.08010   1.00000   0.01165
O6b   0.59650   0.86330   0.57440   1.00000   0.01384
O7b   0.59180   0.75000   0.25930   1.00000   0.01478