Roman mystery iron blades from Serbia

Abstract

A First to Forth Century Roman spear blade from Serbia was found to have an unusual microstructure inconsistent with typical Roman Period iron. An analysis of the blade undertaken at Lehigh University in the US and at the Faculty of Technical Sciences in Novi Sad, Serbia established that it was metallic in appearance, magnetic and had an external layer of red rust. But as metallographically polished, it appeared to contain multiple internal phases and internal cracking. Even after aggressive etching, no typical low carbon microstructure was developed. Scanning electron microscopy, classical and energy dispersive X-ray analysis indicated that the specimen was essentially iron, although its microhardness was too high for typical Roman iron. It was then dubbed "Mystery Iron." Analysis of all the data led to the proposal that it was essentially a Roman iron "fossil" in which the iron had been converted to high temperature iron oxide while retaining the form of the blade, conversion probably occurring in a fire. Subsequent X-ray diffraction analysis confirmed that the blade consisted of FeO and Fe3O4 and the mystery of the iron fossil was at least partially solved. A hypothesis is proposed regarding a potential cause for the fire. © 2008 Elsevier Inc. All rights reserved.