Hematite, ferric oxide, Fe3O2, 69.9 % iron when pure. The most common ore in the world, reddish brown to light brown; usually earthy, not crystalline. Often it is partly hydrated and carries a great deal of gangue.

• 赤铁矿 三氧化二铁，Fe2O3，理论含铁量为69.；9%25。为世界上最普通的铁矿石，呈红褐色或浅褐色，常为土状而非结晶体。含有一定的水份，并含有大量的脉石。