data_Huntite

_chemical_name_systematic          'Calcium trimagnesium carbonate'
_chemical_name_mineral             'Huntite'
_chemical_compound_source          'from Tea Tree Gully, Australia'
_chemical_formula_structural       'Ca Mg3 (C O3)4'
_chemical_formula_sum              'Ca Mg3 O12'

_publ_section_title                
;
Crystal structure refinement of Huntite Ca Mg~3~ (C O~3~)~4~ with X-ray 
powder data
;
loop_
_publ_author_name                  
  'Dollase, W A'
  'Reeder, R J'
_journal_name_full                 'American Mineralogist'
_journal_coden_ASTM                AMMIAY
_journal_volume                    71
_journal_year                      1986
_journal_page_first                163
_journal_page_last                 166

_cell_length_a                     9.5027(6)
_cell_length_b                     9.5027(6)
_cell_length_c                     7.8212(6)
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  120
_cell_volume                       611.6
_cell_formula_units_Z              3

_symmetry_space_group_name_H-M     'R 3 2 H'
_symmetry_Int_Tables_number        155
_symmetry_cell_setting             trigonal

loop_
_symmetry_equiv_pos_as_xyz         
  'x,y,z'
  '-y,x-y,z'
  'y-x,-x,z'
  'y,x,-z'
  'x-y,-y,-z'
  '-x,y-x,-z'
  '1/3+x,2/3+y,2/3+z'
  '2/3+x,1/3+y,1/3+z'
  '1/3-y,2/3+x-y,2/3+z'
  '2/3-y,1/3+x-y,1/3+z'
  '1/3-x+y,2/3-x,2/3+z'
  '2/3-x+y,1/3-x,1/3+z'
  '1/3+y,2/3+x,2/3-z'
  '2/3+y,1/3+x,1/3-z'
  '1/3+x-y,2/3-y,2/3-z'
  '2/3+x-y,1/3-y,1/3-z'
  '1/3-x,2/3-x+y,2/3-z'
  '2/3-x,1/3-x+y,1/3-z'

loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ca2+   2.000
  Mg2+   2.000
  C4+    4.000
  O2-   -2.000

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Ca1   Ca2+   3 a 0. 0. 0. 1.  0 d
  Mg1   Mg2+   9 d 0.5443(7) 0. 0. 1.  0 d
  C1    C4+    3 b 0. 0. 0.5 1.  0 d
  C2    C4+    9 e 0.4535(20) 0. 0.5 1.  0 d
  O1    O2-    9 e 0.8663(15) 0. 0.5 1.  0 d
  O2    O2-    9 e 0.5895(13) 0. 0.5 1.  0 d
  O3    O2-   18 f 0.4569(11) 0.1355(12) 0.5161(11) 1.  0 d

_refine_ls_R_factor_all            0.053



data_Dolomite

_chemical_name_systematic          'Calcium magnesium carbonate'
_chemical_name_mineral             'Dolomite'
_chemical_compound_source          'from Oberdorf, Styria, Austria'
_chemical_formula_structural       'Ca Mg (C O3)2'
_chemical_formula_analytical       'Ca (Mg0.94 Fe0.05 Mn0.01) (C O3)2'
_chemical_formula_sum              'Ca Mg O6'

_publ_section_title                
;
Refinement and Comparison of the Crystal Structures of a Dolomite and 
an Fe-rich Ankerite
;
loop_
_publ_author_name                  
  'Beran, A'
  'Zemann, J'
_journal_name_full                 
;
Tschermaks Mineralogische und Petrographische Mitteilungen (-1978)
;
_journal_coden_ASTM                MPMTAG
_journal_volume                    24
_journal_year                      1977
_journal_page_first                279
_journal_page_last                 286

_cell_length_a                     4.812(1)
_cell_length_b                     4.812(1)
_cell_length_c                     16.01999(300)
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  120
_cell_volume                       321.3
_cell_formula_units_Z              3

_symmetry_space_group_name_H-M     'R -3 H'
_symmetry_Int_Tables_number        148
_symmetry_cell_setting             trigonal

loop_
_symmetry_equiv_pos_as_xyz         
  'x,y,z'
  '-y,x-y,z'
  'y-x,-x,z'
  '-x,-y,-z'
  'y,y-x,-z'
  'x-y,x,-z'
  '1/3+x,2/3+y,2/3+z'
  '2/3+x,1/3+y,1/3+z'
  '1/3-y,2/3+x-y,2/3+z'
  '2/3-y,1/3+x-y,1/3+z'
  '1/3-x+y,2/3-x,2/3+z'
  '2/3-x+y,1/3-x,1/3+z'
  '1/3-x,2/3-y,2/3-z'
  '2/3-x,1/3-y,1/3-z'
  '1/3+y,2/3-x+y,2/3-z'
  '2/3+y,1/3-x+y,1/3-z'
  '1/3+x-y,2/3+x,2/3-z'
  '2/3+x-y,1/3+x,1/3-z'

loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ca2+   2.000
  Mg2+   2.000
  C4+    4.000
  O2-   -2.000

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Ca1   Ca2+   3 a 0. 0. 0. 1.  0 d
  Mg1   Mg2+   3 b 0. 0. 0.5 1.  0 d
  C1    C4+    6 c 0. 0. 0.2429(1) 1.  0 d
  O1    O2-   18 f 0.2485(2) -0.0343(2) 0.2439(1) 1.  0 d

_refine_ls_R_factor_all            0.029