  The M\"ossbauer measurements performed on powdered single crystals of
FeTe0.5Se0.5 (Tc ~ 14.7 K) reveal minor content of two impurity phases,
identified as Fe3O4 and Fe7Se8, among the major tetragonal phase. From the
shape of impurity subspectra it follows that Fe7Se8 behaves in
superparamagnetic manner, most likely because of randomly distributed Fe
vacancies in the lattice structure of Fe Te Se. The magnetite content in the
powdered absorber exposed to ambient air conditions remains unchanged during
period of 16 months. Ageing effects were observed for the samples stored under
argon atmosphere and small increase of the isomer shift of the doublet was
detected. Presented temperature dependence of the hyperfine parameters can be
explained as due to possible orthorhombic distortion or to temperature
behaviour of impurity phases Fe3O4 and Fe7Se8. Strong tendency to formation of
crystalline texture of powdered sample is observed.
