Magnetic epsilon-Fe2O3 nanoparticles embedded in amorphous SiO2 matrix with concentrations of iron oxide of about 20 and 30 wt.% were prepared by the help of ultrasonic activation and subsequent annealing. The structure and properties were analysed by the Mössbauer spectrometry, X-ray diffraction, SEM and HREM and found to strongly depend on the conditions of preparation.