data_9001570
_chemical_name 'Preiswerkite'
loop_
_publ_author_name
'Oberti R'
'Ungaretti L'
'Tlili A'
'Smith D C'
'Robert J-L'
_journal_name_full "American Mineralogist"
_journal_volume 78
_journal_year 1993
_journal_page_first 1290
_journal_page_last 1298
_publ_section_title
;
 The crystal structure of preiswerkite
 Sample: KP17
;
_chemical_formula_sum 'Si2 Al3.15 Mg1.85 Na.85 O12 H2'
_cell_length_a 5.228
_cell_length_b 9.049
_cell_length_c 9.819
_cell_angle_alpha 90
_cell_angle_beta 100.41
_cell_angle_gamma 90
_cell_volume 456.873
_symmetry_space_group_name_H-M 'C 1 2/m 1'
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'
  '-x,y,-z'
  '1/2-x,1/2+y,-z'
  '-x,-y,-z'
  '1/2-x,1/2-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_Uiso_or_equiv
SiT   0.57400   0.16720   0.21390   0.50000 ?
AlT   0.57400   0.16720   0.21390   0.50000 ?
Mg1   0.00000   0.50000   0.50000   0.85000 ?
Al1   0.00000   0.50000   0.50000   0.15000 ?
Mg2   0.00000   0.83020   0.50000   0.50000 ?
Al2   0.00000   0.83020   0.50000   0.50000 ?
Na   0.00000   0.00000   0.00000   0.85000 ?
O1   0.85590   0.19890   0.15840   1.00000 ?
O2   0.45300   0.00000   0.16510   1.00000 ?
O3   0.63480   0.17030   0.39050   1.00000 ?
O-h4   0.12520   0.00000   0.39890   1.00000 ?
H   0.08310   0.00000   0.29500   1.00000   0.01267