data_global
_chemical_name_mineral 'Britholite-(Gd)'
loop_
_publ_author_name
'Hughes J M'
'Mariano A N'
'Drexler J W'
_journal_name_full 'Neues Jahrbuch fur Mineralogie, Monatshefte'
_journal_volume 1992 
_journal_year 1992
_journal_page_first 311
_journal_page_last 319
_publ_section_title
;
 Crystal structures of synthetic Na-REE-Si oxyapatites, synthetic monoclinic britholite
;
_database_code_amcsd 0014863
_chemical_compound_source 'Synthetic'
_chemical_formula_sum '(Gd4.405 Na.595) Si3 O12.81 F.19'
_cell_length_a 9.410
_cell_length_b 9.413
_cell_length_c 6.8740
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120.01
_cell_volume 527.247
_exptl_crystal_density_diffrn      6.294
_symmetry_space_group_name_H-M 'P 1 1 21'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '-x,-y,1/2+z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_U_iso_or_equiv
Gd1a   0.33358   0.66488  -0.00030   0.63600   0.00519
Na1a   0.33358   0.66488  -0.00030   0.36400   0.00519
Gd1b   0.33300   0.66820   0.50050   0.82100   0.01115
Na1b   0.33300   0.66820   0.50050   0.17900   0.01115
Gd2a  -0.00843   0.23358   0.25160   0.98500   0.00570
Na2a  -0.00843   0.23358   0.25160   0.01500   0.00570
Gd2b   0.23361   0.24200   0.75150   0.98300   0.00562
Na2b   0.23361   0.24200   0.75150   0.01700   0.00562
Gd2c   0.24197   0.00841   0.25310   0.98000   0.00540
Na2c   0.24197   0.00841   0.25310   0.02000   0.00540
Si1   0.02780   0.62880   0.25000   1.00000   0.00481
Si2   0.37180   0.39900   0.25300   1.00000   0.00570
Si3   0.60070   0.97200   0.25900   1.00000   0.00545
O1a   0.83060   0.51460   0.24900   1.00000   0.01317
O1b   0.48540   0.31640   0.26400   1.00000   0.01178
O1c   0.68400   0.16890   0.25800   1.00000   0.01381
O2a   0.40160   0.87620   0.26200   1.00000   0.01115
O2b   0.47390   0.59710   0.24900   1.00000   0.01115
O2c   0.12520   0.52610   0.25800   1.00000   0.00899
O3a   0.64050   0.89710   0.05800   1.00000   0.00633
O3b   0.67960   0.92170   0.43300   1.00000   0.00887
O3c   0.25550   0.35900   0.05700   1.00000   0.00887
O3d   0.24220   0.32140   0.43300   1.00000   0.00887
O3e   0.07940   0.75710   0.07800   1.00000   0.00760
O3f   0.10420   0.74600   0.45500   1.00000   0.01140
O   0.00070   0.00040   0.23100   0.81000   0.01773
F   0.00070   0.00040   0.23100   0.19000   0.01773