data_global
_chemical_name_mineral 'Calcite'
loop_
_publ_author_name
'Paquette J'
'Reeder R J'
_journal_name_full 'American Mineralogist'
_journal_volume 75 
_journal_year 1990
_journal_page_first 1151
_journal_page_last 1158
_publ_section_title
;
 Single-crystal X-ray structure refinements of two biogenic magnesian calcite
 crystals
 sample LB
;
_database_code_amcsd 0001328
_chemical_formula_sum '(Ca.871 Mg.129) C O3'
_cell_length_a 4.9382
_cell_length_b 4.9382
_cell_length_c 16.832
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 355.471
_exptl_crystal_density_diffrn      2.748
_symmetry_space_group_name_H-M 'R -3 2/c'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '2/3+x,1/3+y,1/3+z'
  '1/3+x,2/3+y,2/3+z'
  'x,x-y,1/2+z'
  '2/3+x,1/3+x-y,5/6+z'
  '1/3+x,2/3+x-y,1/6+z'
  'y,x,1/2-z'
  '2/3+y,1/3+x,5/6-z'
  '1/3+y,2/3+x,1/6-z'
  '-x+y,y,1/2+z'
  '2/3-x+y,1/3+y,5/6+z'
  '1/3-x+y,2/3+y,1/6+z'
  '-x,-x+y,1/2-z'
  '2/3-x,1/3-x+y,5/6-z'
  '1/3-x,2/3-x+y,1/6-z'
  '-y,-x,1/2+z'
  '2/3-y,1/3-x,5/6+z'
  '1/3-y,2/3-x,1/6+z'
  'x-y,-y,1/2-z'
  '2/3+x-y,1/3-y,5/6-z'
  '1/3+x-y,2/3-y,1/6-z'
  'y,-x+y,-z'
  '2/3+y,1/3-x+y,1/3-z'
  '1/3+y,2/3-x+y,2/3-z'
  '-x+y,-x,z'
  '2/3-x+y,1/3-x,1/3+z'
  '1/3-x+y,2/3-x,2/3+z'
  '-x,-y,-z'
  '2/3-x,1/3-y,1/3-z'
  '1/3-x,2/3-y,2/3-z'
  '-y,x-y,z'
  '2/3-y,1/3+x-y,1/3+z'
  '1/3-y,2/3+x-y,2/3+z'
  'x-y,x,-z'
  '2/3+x-y,1/3+x,1/3-z'
  '1/3+x-y,2/3+x,2/3-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
Ca   0.00000   0.00000   0.00000   0.87100
Mg   0.00000   0.00000   0.00000   0.12900
C   0.00000   0.00000   0.25000   1.00000
O   0.25870   0.00000   0.25000   1.00000
loop_
_atom_site_aniso_label
_atom_site_aniso_U_11
_atom_site_aniso_U_22
_atom_site_aniso_U_33
_atom_site_aniso_U_12
_atom_site_aniso_U_13
_atom_site_aniso_U_23
Ca 0.01760 0.01760 0.01880 0.00880 0.00000 0.00000
Mg 0.01760 0.01760 0.01880 0.00880 0.00000 0.00000
C 0.01584 0.01584 0.02110 0.00792 0.00000 0.00000
O 0.02066 0.04077 0.03717 0.02038 -0.00328 -0.00656