We present a comprehensive investigation of the magnetic, thermodynamic, and transport properties of ${\mathrm{Fe}}_{0.925}{\mathrm{Cr}}_{0.075}\mathrm{Si}$ to clarify the origin of its low-temperature metallic behavior. Although Cr substitution introduces a small number of itinerant $d$ electrons and modestly enhances the high-temperature electronic specific heat, the conduction-electron density of states inferred from ${\chi }_0$ and ${\gamma }_{\mathrm{el}}$ remains low and nearly temperature independent, indicating that impurity-band filling plays only a minor role in establishing metallicity. At elevated temperatures the system behaves as a narrow-gap semiconductor, whereas below 150 K it enters a metal-insulator crossover regime characterized by a competition between a thermally activated insulating channel and an unconventional metallic channel. Magnetic susceptibility, heat capacity, and electrical resistivity consistently demonstrate that this emergent metallic state is driven not by enhanced itinerancy but by strong, predominantly finite-$q$ spin fluctuations with a characteristic scale $T_{\mathrm{SF}}\approx 20\mathrm{K}$. The large low-temperature enhancement of $\gamma$ combined with only a weak increase in the uniform susceptibility yields a Wilson ratio and Stoner enhancement factor far below unity, underscoring the non-Pauli, fluctuation-dominated nature of the metallic state. At the lowest temperatures ($<4\mathrm{K}$), the resistivity upturn is well described by quantum-interference corrections in the dirty-metal limit, indicating that coherence effects develop atop a fluctuation-renormalized diffusive electronic background. These results establish ${\mathrm{Fe}}_{0.925}{\mathrm{Cr}}_{0.075}\mathrm{Si}$ as a rare example of a correlated semiconductor in which a spin-fluctuation-induced metallic phase dominates over impurity-band contributions and evolves into a quantum-corrected regime at ultralow temperatures.

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• Electrical properties
• Magnetic interactions
• Magnetic phase transitions
• Magnetic susceptibility
• Magnetization dynamics
• Quantum interference effects