  It is theoretically and numerically demonstrated that a mixture of two
topologically distinct material phases is characterized by an anomalous
"transparency window" in a spectral range wherein the individual material
phases are strongly reflecting. In particular, it is shown that a metamaterial
formed by a metallic wire grid embedded in a magnetized plasma may support the
propagation of waves with long wavelengths, notwithstanding the components,
when taken separately, completely block the electromagnetic radiation. The
effect is explained in terms of the topological properties of the
magnetoplasmon. Furthermore, it is highlighted that some naturally available
materials may be regarded as a mixture of two topologically distinct phases,
and hence may be as well characterized by a similar anomalous transparency
effect.
