Steel
noun
はがね
鋼 （はがね） Steel
鋼鉄 （こうてつ、not on WK） Steel
鋼材 （こうざい） Steel Material
製鋼 （せいこう） Steel Manufacture
青銅 （せいどう、alloy） Bronze
鋼 （はがね、alloy） Steel
鉄鉱 （てっこう） Iron Ore
鉄 （てつ、not on WK） Iron
Iron is an element while steel is an alloy comprised of iron and carbon. Steel is man made, so you won't find it in nature. You won't find steel in ore, only iron which can be manufactured into steel.