  We report anomalous physical properties of single-crystalline FeSi over a
wide temperature range 1.8-400 K. X-ray diffraction, specific heat, and
magnetization measurements indicate that the FeSi crystals synthesized in this
study are of high quality with a very low concentration of magnetic impurities
($\sim$0.01$\%$). The electrical resistivity $\rho$($T$) can be described by
activated behavior with an energy gap $\Delta$ = 57 meV between 67 K and 150 K.
At temperatures below 67 K, $\rho$($T$) is significantly lower than an
extrapolation of the activated behavior, and the Hall coefficient and
magneto-resistivity undergo a sign change in this region. At $\sim$19 K, a
transition from semiconducting to metallic-like behavior is observed with
deceasing temperature. Whereas the transition temperature is very robust in a
magnetic field, the magnitude of the resistivity below $\sim$30 K is very
sensitive to magnetic field. There is no indication of a bulk phase transition
or onset of magnetic order in the vicinity of either 67 K or 19 K from specific
heat and magnetic susceptibility measurements. These measurements provide
evidence for a conducting surface state in FeSi at low temperatures.
