| Section3 = }} Calcium oxide (CaO), commonly known as burnt lime, lime or quicklime, is a widely used chemical compound. It is a white, caustic and alkaline crystalline solid. As a commercial product, lime often also contains magnesium oxide, silicon oxide and smaller amounts of aluminium oxide and iron oxide. Calcium oxide is usually made by the thermal decomposition of materials such as limestone, that contain calcium carbonate (CaCO3; mineral name: calcite) in a lime kiln. This is accomplis… (More on Quicklime)