Radiogenic iron

— This historical review focuses on the idea that this very abundant chemical element was overwhelmingly created and ejected from the stars not in its own chemical form but that of radioactive Ni progenitors. Iron in the universe outnumbers all of the common metals. Its thermonuclear origin provided the beginnings for the theory of nucleosynthesis in stars. Three of its isotopes (masses 54, 56, and 57) are counted among the most prominent isotopes of any element. Two of these isotopes ( 56 Fe and 57 Fe) are now known to have derived naturally from the radioactive decay of Ni isobars outside of exploding stars. Tension and numerous mistakes surrounding the discovery of its radiogenic origin are analyzed with historical accuracy. The radioactive origin is described as having been first overlooked and later resisted to considerable degree. But incontrovertible evidence, especially from supernova light curves and gamma‐ray‐line astronomy, has established its correctness. Radiogenic Fe thus remains the centerpiece for both the theory and the observations of nucleosynthesis in stars.