What are the two types of Iron oxide?
Iron oxides are classified into four types: wustite
\begin{equation}
Fe_{1-x}O
\end{equation}
, magnetite (Fe3O4 ), maghemite
\begin{equation}
\gamma -Fe_{2}O_{3}
\end{equation}
, and haematite
\begin{equation}
\alpha -Fe_{2}O_{3}
\end{equation}