#------------------------------------------------------------------------------
#$Date: 2008-01-14 00:15:36 +0200 (Mon, 14 Jan 2008) $
#$Revision: 14 $
#$URL: file:///home/coder/svn-repositories/cod/cif/1/1010215.cif $
#------------------------------------------------------------------------------
#
# This file is available in the Crystallography Open Database (COD),
# http://www.crystallography.net/
#
# All data on this site have been placed in the public domain by the
# contributors.
#
data_1010215
_chemical_name_systematic          'Dicalcium magnesium disilicate'
_chemical_formula_structural       'Ca2 Mg Si2 O7'
_chemical_formula_analytical       '(Ca, Na)2 (Mg, Al)1 (Si, Al)2 O7'
_chemical_formula_sum              'Ca2 Mg O7 Si2'
_publ_section_title
;
The Structure of Melitite (Ca, Na)~2~ (Mg, Al)~1~ (Si, Al)~2~ O~7~
;
_publ_author_name                  'Warren, B E'
_journal_name_full
;
Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik,
Kristallchemie (-144,1977)
;
_journal_coden_ASTM                ZEKGAX
_journal_volume                    74
_journal_year                      1930
_journal_page_first                131
_journal_page_last                 138
_cell_length_a                     7.73
_cell_length_b                     7.73
_cell_length_c                     5.01
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  90
_cell_volume                       299.4
_cell_formula_units_Z              2
_symmetry_space_group_name_H-M     'P -4 21 m'
_symmetry_Int_Tables_number        113
_symmetry_cell_setting             tetragonal
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '1/2-x,1/2+y,-z'
  '-x,-y,z'
  '1/2+x,1/2-y,-z'
  '-y,x,-z'
  '1/2+y,1/2+x,z'
  'y,-x,-z'
  '1/2-y,1/2-x,z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ca2+   2.000
  Si4+   4.000
  Mg2+   2.000
  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+   4 e 0.33 0.17 -0.49 1.  0 d
  Si1   Si4+   4 e 0.14 0.36 -0.05 1.  0 d
  Mg1   Mg2+   2 a 0. 0. 0. 1.  0 d
  O1    O2-    2 c 0.5 0. 0.19 1.  0 d
  O2    O2-    4 e 0.14 0.36 0.26 1.  0 d
  O3    O2-    8 f 0.08 0.18 -0.19 1.  0 d