What is the formula of iron and aluminium oxides/ores?

Answer 1

Iron ores are various forms of iron oxide, rust, Fe2O3,
"Altogether there are 16 known iron oxides.[1]
These compounds are either oxides (Hematite, Magnetite, Maghemite, β-Fe2O3, ε-Fe2O3, Wüstite), or hydroxides and oxide-hydroxides (Goethite, Lepidocrocite, Akageneite, Schwertmannite, Feroxyhyte, δ-FeOOH, high pressure FeOOH, Ferrihydrite, Bernalite, Fe(OH)2, green rusts)."
http://en.wikipedia.org/wiki/Iron_oxide
Aluminum ores are Aluminum (Aluminium) Hydoxide -
"Bauxite is an aluminium ore which consists largely of the Al minerals gibbsite Al(OH)3, boehmite and diaspore AlOOH, together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2. "
http://en.wikipedia.org/wiki/Bauxite