Iron is a relatively abundant element in the universe. It is found in the sun and many types of stars in considerable quantity. Its nuclei are very stable. The metal is the fourth most abundant element, by weight, making up the crust of the earth. Taconite is becoming increasingly important as a commercial ore.
Common iron is a mixture of four isotopes.
Ten other isotopes are known to exist. Iron is a vital constituent of plant and animal life, and appears in hemoglobin. The pure metal is not often encountered in commerce, but is usually alloyed with carbon or other metals. The pure metal is very reactive chemically, and rapidly corrodes, especially in moist air or at elevated temperatures. The alpha form is magnetic, but when transformed into the beta form, the magnetism disappears although the lattice remains unchanged.