magnetite

noun2

1. •
   A magnetic mineral, with the chemical formula Fe²⁺Fe3+2O₄, one of the primary ores of iron.

   • Appropriately enough, the commonest of these, a simple iron oxide, is called magnetite. — 2004
2. •
   Any instance of iron(II,III) oxide, regardless of whether it is a geologic mineral or a chemical result or product.