Iron oxide is an inorganic compound with higher iron content. It is also called a ferric oxide and is one of the three main oxides of iron. Ferric trioxide, a mineral named hematite, is the main source of iron for the steel industry. It is readily attacked by acids. Iron oxide is known as rust because rust having similar compositions shares several properties. In chemistry, rust is taken as an ill-defined material, described as Hydrous ferric oxide. It appears as a reddish-brown solid. Its crystal structure is rhombohedral. It reacts with water and Sulphuric acid. It is an odorless substance that is insoluble in water but highly soluble in acids. It occurs in abundance naturally.