Iron oxide is a kind of inorganic matter, the chemical formula is Fe2O3, which is red or dark red amorphous powder. 25, melting point 1565 ℃ (simultaneous decomposition). Insoluble in water, soluble in hydrochloric acid and sulfuric acid, slightly soluble in nitric acid. Covering power and coloring power are very strong, no oil permeability and water permeability. Stable in atmosphere and sunlight, resistant to dirty gas, high temperature and alkali. The crystal grains of dry process products are coarse and hard, which are suitable for magnetic materials, polishing and grinding materials. The crystal particles of wet process products are fine and soft, which is suitable for coating and ink industry.

　　Red to reddish brown powder. Odorless. Insoluble in water, organic acids and organic solvents. Soluble in inorganic acids. There are two types: α - type (positive magnetism) and γ - type (diamagnetism). The fineness of dry process products is generally less than 1 μ M. Stable to light, heat and air. It is stable to acid and alkali. Strong coloring power. The refractive index is 3.042. Melting point 1550 ℃, about 1565 ℃.