data_9001999
_chemical_name 'Fluoro-eckermannite'
loop_
_publ_author_name
'Oberti R'
'Hawthorne F C'
'Camara F'
'Raudsepp M'
_journal_name_full "American Mineralogist"
_journal_volume 84
_journal_year 1999
_journal_page_first 102
_journal_page_last 111
_publ_section_title
;
 Unusual M3+ cations in synthetic amphiboles with nominal fluoro-eckermannite
 composition: Deviations from stoichiometry and structural effects of the
 cummingtonite component
 Sample: Ga, Na.94Na1.07Mg.93Mg4.87Ga.13Si8O22F2
;
_chemical_formula_sum 'Si8 Mg5.8 Ga.14 Na2.02 O22 F2'
_cell_length_a 9.666
_cell_length_b 17.902
_cell_length_c 5.272
_cell_angle_alpha 90
_cell_angle_beta 102.84
_cell_angle_gamma 90
_cell_volume 889.459
_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
Si(1)   0.28440   0.08490   0.28360   1.00000   0.00557
Si(2)   0.29210   0.17070   0.78780   1.00000   0.00709
Mg(1)   0.00000   0.08890   0.50000   1.00000   0.00912
Ga(2)   0.00000   0.17980   0.00000   0.07000   0.00975
Mg(2)   0.00000   0.17980   0.00000   0.93000   0.00975
Mg(3)   0.00000   0.00000   0.00000   1.00000   0.00798
Mg(4)   0.00000   0.26430   0.50000   0.47000   0.02330
Na(4)   0.00000   0.26430   0.50000   0.53000   0.02330
NaA   0.00000   0.50000   0.00000   0.26000   0.03331
NaA(m)   0.04440   0.50000   0.10150   0.35000   0.03521
O1   0.11390   0.08500   0.21340   1.00000   0.00595
O2   0.12040   0.16950   0.72310   1.00000   0.01001
F3   0.10370   0.00000   0.70710   1.00000   0.00925
O4   0.36830   0.24850   0.78460   1.00000   0.01748
O5   0.35040   0.12840   0.06960   1.00000   0.01976
O6   0.34680   0.11870   0.57080   1.00000   0.02647
O7   0.34560   0.00000   0.28380   1.00000   0.01456