Magnetite n. : An 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 loadstone. It is an important iron ore. Called also magnetic iron.

Example:
suppose you cut the the Magnetite sample in half. What is the density of Magnetite?

Taxonomy
Magnetite, deposits, iron, mineral, magma, hematite, free encyclopedia, rocks, rpm, ilmenite, igneous rocks, oxide, sorbent, Mining, chemical formula, iron oxides, Fe2O3, oxidation states.

Defination from the web:
Magnetite is a ferrimagnetic mineral with chemical formula Fe 3O 4, one of several iron oxides and a member of the spinel group. ... The formula for magnetite may also be written as FeO·Fe2O3, which is one part wüstite (FeO) and one ... The Curie temperature of magnetite is 858 K. ...