Without water, rust is Fe2O3. It's commonly used as red die for cements and cheapest iron oxide. It's also useful with aluminum to make thermite (which generate

Without water, rust is Fe2O3. It's commonly used as red die for cements and cheapest iron oxide. It's also useful with aluminum to make thermite (which generates VERY high temperatures). Long ago I bought some Fe2O3, it was very fine powder and apparently waste from some chemical process. Edit - mistook oxides.