When a metal is defined as non-ferrous it means that it does not have a significant amount of iron in its chemical composition. Note the word “significant”; nearly all metal alloys have some trace, or non-significant, amount of iron in their composition. This does not make them ferrous alloys though. Non-ferrous alloys generally have iron compositions of less than one percent as measured by weight. If iron constitutes a large percentage of a metal, such as if it is the first or second most abundant element in the metal’s chemical composition, then the metal is considered ferrous.