Features of the spectrum of the Faraday effect in FeBO$_3$ caused by the magnetization component of the parallel $C_3$ axis

For the first time, the spectral dependence of the Faraday effect caused by the magnetization of the parallel $C_3$ axis of the crystal was measured in the area of its transparency in iron borate. Based on the spectral dependence, the peak of the effect was observed at a wavelength of light equal to 475 nm. The origin of the peak in the spectral dependence of the effect is associated with the transition (${}^6A_{1g}\to{}^4A_{1g}$, $^4E_g$) in the Fe$^{3+}$ iron borate ion.