Natural and well-crystallized hematite was suspended in water and treated at room-temperature (RT) with sodium borohydride in acid medium. The product of the reaction is a highly magnetic black powder, which is stable at RT. The NaBH4 treatment converts about half of the hematite to an amorphous Fe-B alloy and to a small fraction of sub-micron sized, amorphous metallic-Fe nodules. Heating at 400 degrees C of this composite has resulted in the crystallization and/or oxidation of more than half of the amorphous Fe-B phase to alpha-Fe and Fe3O4 and B2O3, respectively. Further, the already present superficial, amorphous metallic Fe is converted to alpha-Fe and the original, plate like morphology of the hematite has changed to a mix of nodular and acicular particles. After treatment at 800 degrees C, the metallic Fe and the amorphous Fe-B have completely vanished, and the resulting product consists of hematite and FeBO3 embedded in a matrix of alpha-Fe2O3.