The paper is devoted to study of the charge carrier transfer characteristics in the silicon microcrystals doped by boron to concentrations corresponding to the metal-dielectric transition, as well as modified by a transition metal admixture with an unfilled 3d+ shell of the local magnetic moment. The magnetoresistance of microcrystals under the magnetic field action to 14 T at the cryogenic temperatures was studied. A detailed analysis of the results of studies of magneto-transport properties of crystals was carried out. It was found that the low-temperature transport of charge carriers for silicon microcrystals is based on hopping polarization conduction. Based on the results of the magnetization study of Si <B, Ni> crystals, the concentration of magnetic centers was determined, which is 4×1017cm-3. The use of silicon microcrystals in magnetic field sensors with the magnetoresistive principle of operation is proposed