# What are the oxidation numbers for iron oxide, Fe_3O_4?

This is a mixed valence compound of $F e \left(I I\right)$ and $F e \left(I I I\right)$.
If we write $F {e}_{2} {O}_{3} \cdot F e O$ the formulation is easier to consider. $F {e}_{3} {O}_{4}$ occurs naturally as the mineral magnetite. Iron oxide chemistry is a very broad church and many mixed oxides and oxidation states are available.