data_1011147
_chemical_name_systematic          'Discandium disilicate'
_chemical_name_mineral             'Thortveitite'
_chemical_compound_source          'from Iveland, Saetersdalen, S. Norway'
_chemical_formula_structural       'Sc2 (Si2 O7)'
_chemical_formula_sum              'O7 Sc2 Si2'
_publ_section_title                'The structure of thortveitite, Sc2 Si O7'
_publ_author_name                  'Zachariasen, W H'
_journal_name_full
;
Zeitschrift fuer Kristallographie, Kristallgeometrie, Kristallphysik,
Kristallchemie (-144,1977)
;
_journal_coden_ASTM                ZEKGAX
_journal_volume                    73
_journal_year                      1930
_journal_page_first                1
_journal_page_last                 6
_cell_length_a                     6.56
_cell_length_b                     8.58
_cell_length_c                     4.74
_cell_angle_alpha                  90
_cell_angle_beta                   103.13
_cell_angle_gamma                  90
_cell_volume                       259.8
_cell_formula_units_Z              2
_exptl_crystal_density_meas        3.5
_symmetry_space_group_name_H-M     'C 1 2/m 1'
_symmetry_Int_Tables_number        12
_symmetry_cell_setting             monoclinic
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  'x,-y,z'
  '-x,-y,-z'
  '-x,y,-z'
  '1/2+x,1/2+y,z'
  '1/2+x,1/2-y,z'
  '1/2-x,1/2-y,-z'
  '1/2-x,1/2+y,-z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Sc3+   3.000
  Si4+   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
  Sc1   Sc3+   4 h 0. 0.3 0.5 1.  0 d
  Si1   Si4+   4 i 0.222 0. -0.064 1.  0 d
  O1    O2-    2 a 0. 0. 0. 1.  0 d
  O2    O2-    4 i 0.403 0. 0.233 1.  0 d
  O3    O2-    8 j 0.25 0.15 -0.269 1.  0 d