MINERALOGICAL, MAGNETIC AND MOSSBAUER DATA OF SMYTHITE (FE9S11)

The mineralogical and magnetic properties of the magnetic iron-sulfide smythite (Fe9S11) fro the Sokolov Basin, Czech Republic, were studied . Our experimental results show that smythite is hexagonal with cell e dges a0 = 3.468 angstrom and c0 = 34.470 angstrom. Thermomagnetic meas urements M(s)(T) (M(s): saturation magnetization) and chi(T) (chi: sus ceptibility) were performed in order to study the thermal alteration o f the smythite. Its Curie point could not be determined. The hysteresi s loops had a shape typical for SD - grains with relatively low values of saturation magnetization (M(s) = 10.3 Am2/kg) and coercive forces of almost-equal-to 37 mT. Similarities in the magnetic, crystallograph ic, and the Mossbauer parameters to the structure of pyrrhotite (F27S8 ) suggest that smythite could be antiferromagnetic with vacancy orderi ng resulting in a small net magnetic moment similar to that in pyrrhot ite.