data_global
_chemical_name_mineral 'Tachyhydrite'
loop_
_publ_author_name
'Clark J R'
'Evans H T'
'Erd R C'
_journal_name_full 'Acta Crystallographica, Section B'
_journal_volume 36 
_journal_year 1980
_journal_page_first 2736
_journal_page_last 2739
_publ_section_title
;
 Tachyhydrite, dimagnesium calcium chloride 12-hydrate
;
_database_code_amcsd 0009720
_chemical_compound_source 'Synthetic'
_chemical_formula_sum 'Ca Cl6 Mg2 O12 H24'
_cell_length_a 10.136
_cell_length_b 10.136
_cell_length_c 17.318
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 1540.854
_exptl_crystal_density_diffrn      1.673
_symmetry_space_group_name_H-M 'R -3'
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'
  '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
Ca   0.00000   0.00000   0.00000
Cl   0.17800  -0.06880   0.09260
Mg   0.00000   0.00000   0.32430
O1   0.18820   0.07000   0.25480
O2  -0.18970  -0.06280   0.39200
H1   0.18000   0.04000   0.20600
H2   0.27000   0.18000   0.26300
H3  -0.20000   0.02000   0.41600
H4  -0.23000  -0.16000   0.41700
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 0.03100 0.03100 0.03380 0.01550 0.00000 0.00000
Cl 0.04760 0.04650 0.04230 0.02990 -0.00440 -0.00360
Mg 0.03020 0.03020 0.03340 0.01510 0.00000 0.00000
O1 0.03800 0.05200 0.04200 0.01600 0.00600 0.00000
O2 0.04500 0.05000 0.06000 0.02300 0.01600 0.00400