Biological Role Iron is an essential and non-toxic element. It is part of the active site of haemoglobin, and carries oxygen in the bloodstream. Insufficient iron in the blood is the cause of anaemia. General Information Pure iron is very reactive chemically and rapidly rusts, especially in moist air or high temperatures. It dissolved in dilute acids.
Iron exists as four allotropic forms, one of which is magnetic.
The relationship between these forms is not properly understood. A remarkable wrought iron pillar which dates from A.D. 400 still stands today in Delhi, India. It is 7.25m high and 40cm in diameter. Corrosion to the pillar has been minimal although it has been constantly exposed to the weather.