A method for producing silicate-containing magnetic particles having a closed and tight silicate layer and high purity. In addition, the novel method prevents an uncontrolled formation of aggregates and clusters of silicates on the magnetite surface, thereby having a positive influence on the properties and biological applications. The method enables depletion of nanoparticulate solid substance particles on the basis of a fractionated centrifugation. The silicate-coated magnetic particles exhibit optimized magnetization and suspension behavior as well as advantageous run-off behavior from plastic surfaces. These highly pure magnetic particles coated with silicon dioxide are preferably used for isolating nucleic acids from cell and tissue samples, whereby the separating out from a sample matrix ensues by means of magnetic fields. The particles are particularly well suited for the automatic purification of nucleic acids, mostly from biological body samples for the purpose of analyzing them with different amplification methods.