‘The sword that was broken …’: The detection of recycled iron in the archaeological record

Abstract

Although the recycling of materials such as copper and glass is widely known and generally well understood within archaeological contexts, far less is known about the recycling of iron. Iron recycling is more complex than that of other metals for two reasons. First, normal manufacturing processes, which include forging several components to make a composite object, offer the opportunity to include recycled iron. Second, the material itself is more complex than Cu alloys. The alloys of Fe, depending primarily on C content, are very different in terms of properties and can be interconverted by (normally) removing C such as decarburizing cast iron to make wrought iron. Thus, recycling practices are potentially intimately combined with such processes. These factors, combined with the poor preservation of archaeological iron and the consequent reluctance to carry out extensive studies (which often require destructive analysis via metallography), mean that there are no clear criteria for identifying recycled iron. However, limited historical documentation suggests, at least indirectly, that such recycling was common. This paper is neither comprehensive nor definitive, but merely intends to promote discussion and awareness of iron recycling by hypothesizing several possible mechanisms and providing a few illustrative archaeological examples.