The interest for core-shells has been increased in the recent years due to their improved and modifiable properties. In this work, Fe3O4-TiO2 and Fe3O4-SiO2 core-shells were successfully synthesized from an industrially produced magnetite-rich powder with micro- and nanometric particle sizes, superparamagnetic behavior and saturation magnetization of 49 emu/g. The reverse microemulsion method was used to the synthesis of these core-shells. X-ray diffraction, energy dispersive X-ray analysis, electron microscopy (SEM-TEM), and magnetization curves were used to characterize the solids. Core-shells with different morphology and size, coating of crystalline TiO2 (anatase) or amorphous silica, and superparamagnetic performance at room temperature (300 K) were obtained.