Reevaluating early iron-working skills in the Southern Levant through microstructure analysis

The question of whether improved technological skills of Iron Age smiths, such as carburization and quenching, were behind the significant transition to utilitarian use of iron in the eastern Mediterranean has been long debated, with the answer relying on the analyses of a few exceptionally well-preserved objects from Israel and Cyprus. In order to systematically examine this question, 59 iron objects from several major Iron Age settlements in Israel were sampled for metallographic analysis. First and foremost, it is shown that none of the analyzed objects were preserved in metallic form and that only in rare cases, small islands of metallic iron were preserved. Objects with full preservation of metal, heavily relied upon in past discussions, are therefore the exception and not the rule. Using relics (“ghost structures”) of the original metallic microstructure, pearlite and cementite were observed in an overwhelming majority of the samples, indicating that almost all of the objects were made of steel. A wide variety of carbon concentrations was estimated, reflecting a range of compositions from low-carbon hypoeutectoid to high-carbon and hypereutectoid steels. Since no clear correlation between object type and steel quality was observed, we conclude that steeling was, in fact, a spontaneous and non-deliberate result of the smelting process, rather than a deliberate systematic act of carburization. In addition, martensitic structures, indicative of quenching, were not identified, suggesting that quenching was not routinely performed and that iron was unlikely to have been superior to bronze at this time. It thus appears that the iron-working skills of the Iron Age smiths cannot be used as a factor that can explain the advent of iron in the Southern Levant nor as a reason for the dramatic increase in iron production during the 10th–9th centuries BCE.