data_global
_chemical_name_mineral 'Calcite'
loop_
_publ_author_name
'Effenberger H'
'Mereiter K'
'Zemann J'
_journal_name_full 'Zeitschrift fur Kristallographie'
_journal_volume 156 
_journal_year 1981
_journal_page_first 233
_journal_page_last 243
_publ_section_title
;
 Crystal structure refinements of magnesite, calcite, rhodochrosite, siderite,
 smithsonite, and dolomite, with discussion of some aspects of the
 stereochemistry of calcite type carbonates
;
_database_code_amcsd 0020835
_chemical_compound_source 'Iceland'
_chemical_formula_sum '(Ca.99 Mg.01) C O3'
_cell_length_a 4.9896
_cell_length_b 4.9896
_cell_length_c 17.0610
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 367.846
_exptl_crystal_density_diffrn      2.707
_symmetry_space_group_name_H-M 'R -3 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   0.99000
Mg   0.00000   0.00000   0.00000   0.01000
C   0.00000   0.00000   0.25000   1.00000
O   0.25682   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 0.00989 0.00989 0.00972 0.00495 0.00000 0.00000
Mg 0.00989 0.00989 0.00972 0.00495 0.00000 0.00000
C 0.00851 0.00851 0.01161 0.00426 0.00000 0.00000
O 0.01108 0.02176 0.02057 0.01088 -0.00411 -0.00822