data_global
_chemical_name_mineral 'Halloysite'
loop_
_publ_author_name
'Mehmel M'
_journal_name_full 'Zeitschrift fur Kristallographie'
_journal_volume 90 
_journal_year 1935
_journal_page_first 35
_journal_page_last 43
_publ_section_title
;
 Uber die Struktur von Halloysit und Metahalloysit
;
_database_code_amcsd 0018093
_chemical_compound_source 'not given'
_chemical_formula_sum 'Al2 Si2 (O9 H4)'
_cell_length_a 5.15
_cell_length_b 8.9
_cell_length_c 7.57
_cell_angle_alpha 90
_cell_angle_beta 100.
_cell_angle_gamma 90
_cell_volume 341.700
_exptl_crystal_density_diffrn      2.509
_symmetry_space_group_name_H-M 'C 1 m 1'
loop_
_space_group_symop_operation_xyz
  '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
Al   0.25000   0.16667   0.00000
Si   0.00800   0.16667   0.43300
O-H1   0.45400   0.00000   0.15900
O-H2   0.54600   0.50000  -0.15900
O-H3   0.04600   0.33300  -0.15900
O1   0.00800   0.00000   0.54200
O2   0.28300   0.25000   0.54200
O3  -0.04600  -0.16700   0.15900