Fluoro-eckermannite
Oberti R, Hawthorne F C, Camara F, Raudsepp M
American Mineralogist 84 (1999) 102-111
Unusual M3+ cations in synthetic amphiboles with nominal fluoro-eckermannite
composition: Deviations from stoichiometry and structural effects of the
cummingtonite component
Sample: Al, Na.98Na1.10Mg.90Mg4.88Al.12Si8O22F2
_database_code_amcsd 0002055
9.668 17.916 5.271 90 102.82 90 C2/m
atom       x     y     z occ Biso
Si(1)  .2842 .0848 .2830      .57
Si(2)  .2922 .1706 .7872      .67
Mg(1)      0 .0887    .5      .69
Mg(2)      0 .1793     0 .94  .89
Al(2)      0 .1793     0 .06  .89
Mg(3)      0     0     0      .66
Na(4)      0 .2638    .5 .56 1.83
Mg(4)      0 .2638    .5 .44 1.83
NaA        0    .5     0 .29 3.11
NaA(m) .0464    .5 .1122 .35 2.67
O1     .1143 .0847 .2140      .78
O2     .1208 .1698 .7216      .86
F3     .1045     0 .7074      .79
O4     .3683 .2488 .7836     1.56
O5     .3505 .1277 .0674     1.80
O6     .3473 .1194 .5681     2.20
O7     .3454     0 .2837     1.19