iron peak element

An iron peak element is an element with an atomic number in the vicinity of iron's (26), i.e., the vicinity of the iron peak:

Scandium, Sc, 21 is also sometimes treated as one. A common astrophysics classification of (somewhat heavy) elements is as either an iron peak element or an alpha element, even though the even-numbered iron peak elements can be produced by the alpha process. The distinction is made because some types of supernova tend to produce a lot more iron peak elements relative to alpha elements, i.e., the relative abundances of the two groups reveal information of past supernovae and star formation history.