A metallic element, atomic no. 26, atomic wt. 55.847, which occurs in the heme of hemoglobin, myoglobin, transferrin, ferritin, and iron-containing porphyrins, and is an essential component of enzymes such as catalase, peroxidase, and the various cytochromes; its salts are used medicinally. For individual salts not listed below, see ferric and ferrous entries. [A.S. iren]
