  The in-plane optical properties of the inhomogeneous iron-chalcogenide
superconductor K_{0.8}Fe_{2-y}Se_2 with a critical temperature Tc = 31 K have
been modeled in the normal state using the Bruggeman effective medium
approximation for metallic inclusions in an insulating matrix. The volume
fraction for the inclusions is estimated to be ~ 10%; however, they appear to
be highly distorted, suggesting a filamentary network of conducting regions
joined through weak links. The value for the Drude plasma frequency in the
inclusions is much larger than the volume average, which when considered with
the reasonably low values for the scattering rate, suggests that the transport
in the grains is always metallic. Estimates for the dc conductivity and the
superfluid density in the grains places the inclusions on the universal scaling
line close to the other homogeneous iron-based superconductors.
