If you are asking about Tony Stark then he is made of the same elements you are. 99% of the human body is made up of six elements oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Less than 1% is made up of potassium, sulphur, sodium, chlorine, and magnesium and about 12 others like caesium, titanium and even mercury.
If you are asking about his suit then the first version “Mark I” was an allow of iron, copper and magnesium from disassembled Stark mortar cannons. The “Mark II” suit was much lighter and more flexible and was made mainly from silver and stainless steel, which is an alloy of iron, carbon and chromium. The “Mark III” suit was made from a gold-titanium alloy, to overcome the problem of freezing when flying at higher altitudes. Although, this particular alloy doesn’t exist in reality as the actual percentages of gold and titanium wouldn’t work, TitaniumGold is used in dentistry for fillings, crowns and bridges.
If you are just asking “what element is iron, man?” then Iron is a chemical element with the symbol “Fe” from the Latin word “ferrum”.