magnetite

from WordNet (r) 3.0 (2006)

magnetite
    n 1: an oxide of iron that is strongly attracted by magnets
         [syn: {magnetite}, {magnetic iron-ore}]

from The Collaborative International Dictionary of English v.0.48

Magnetite \Mag"net*ite\, n. (Min.)
   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}.
   [1913 Webster]