magnetite
nounThe mineral form of black iron oxide, Fe3O4, that often occurs with magnesium, zinc, and manganese and is an important ore of iron.
nounMagnetic oxid of iron; a black oxid of iron (Fe3O4 or FeO.Fe2O3) which is strongly attractable by a magnet.
nounAn oxide of iron (Fe3O4) occurring in isometric crystals, also massive, of a black color and metallic luster. It is readily attracted by a magnet and sometimes possesses polarity, being then called
A
an oxide of iron that is strongly attracted by magnets