Iron oxide is a black crystalline or reddish brown powder. It is used for polishing compounds, ceramics and metallurgy.

　　When iron containing materials are heated, such as arc welding, iron oxide fumes are produced. DOT UN 1276 refers to ferrous oxide, iron oxide or iron sponge. Ferrous oxide may be foamed in flue gas and in gas purification in the limited atmosphere of oxygen.

　　Iron is heated to below the melting point of iron. With further processing, they become iron.