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: Sc, Na.92Na1.97Mg.03Mg3.95Sc1.05Si8O22F2
_database_code_amcsd 0002056
9.820 18.036 5.290 90 103.64 90 C2/m
atom       x     y     z occ Biso
Si(1)  .2827 .0845 .2907      .36
Si(2)  .2883 .1695 .7953      .43
Mg(1)      0 .0884    .5      .51
Sc(2)      0 .1815     0 .53  .48
Mg(2)      0 .1815     0 .47  .48
Mg(3)      0     0     0      .51
Na(4)      0 .2760    .5 .97 2.01
Mg(4)      0 .2760    .5 .03 2.01
NaA        0    .5     0 .27 2.01
NaA(m) .0407    .5 .0937 .52 2.33
NaA(2)     0 .4749     0 .20 3.07
O1     .1141 .0846 .2160      .47
O2     .1194 .1659 .7265      .49
F3     .1012     0 .7097      .59
O4     .3600 .2483 .7968      .78
O5     .3490 .1274 .0783      .73
O6     .3445 .1180 .5789      .72
O7     .3427     0 .2907      .71