The method of borehole magnetic exploration is currently applied almost exclusively to magnetite deposits of various genetic types. There is practically no experience in staging this method on relatively weakly magnetic objects. This is explained mainly by insufficient resolution of modern borehole magnetometers, which do not allow to measure the magnetic field in the borehole with an accuracy higher than ± (1000 - 1500) gamma for the full field vector and 500 gamma for its vertical component.