Aluminum oxide in Changshu oxidation plant is a white solid, a compound of aluminum and oxygen, with the molecular formula of Al2O3. It is also called bauxite in mining, ceramics and material science. The common purity is 99.5% and 96%.

In 1961, General Electric (GE) produced "Lucalox", a transparent bauxite used in sodium lamps. In Changshu oxidation plant, the content of aluminum oxide is the highest in the main component of aluminum ore, bauxite. Industrially, the bauxite is purified by Bayer process into aluminum oxide:

1. The main components of ruby and sapphire are aluminum oxide, which presents different colors due to other impurities. Ruby is red with chromium oxide, while sapphire is blue with iron oxide and titanium dioxide.

2. Aluminum oxidation is the reason why metal aluminum is not easy to be corroded in the air. The pure metal aluminum of Changshu oxidation plant easily reacts with oxygen in the air to form a thin aluminum oxide film to cover the aluminum surface exposed to the air. This aluminum oxide film can prevent aluminum from being further oxidized. The thickness and properties of this oxide film can be enhanced by a treatment process called anodic treatment (anodic corrosion prevention).

3. Aluminum is a good conductor of electricity and heat, while aluminum oxidation is the insulator of electricity and heat. Aluminum oxide crystal corundum is suitable for grinding materials and cutting tools because of its high hardness.

4. Aluminum oxide powder is often used as the medium of color layer analysis.