Iron is a shiny, greyish metal that rusts in damp air. It has the symbol Fe and atomic number 26 on the periodic chart. Iron, by mass, is the most common element on Earth, right in front of oxygen, and the fourth most common element in the Earth’s crust. Although iron readily reacts, high purity iron, called electrolytic iron, has better corrosion resistance.

Iron is also naturally found in many foods and food additives as well as a dietary supplement. It is a necessary component of hemoglobin in the transfer of oxygen from the lungs to the tissues. An adult human contains about 4 grams, mostly in hemoglobin and myoglobin.