Non-invasive quantitative phase analysis and microstructural properties of an iron fragment retrieved in the copper-age Selvicciola Necropolis in southern Tuscia

Abstract

This work presents the non-invasive analysis, through time of flight neutron diffraction, of a unique grey metal ferrous artefact in the shape of an awl. This object was found together with other copper samples in the Selvicciola Necropolis, which includes 34 eneolithic underground tombs, dated radiometrically between halfway through the fourth millennium and the end of the third millennium BC. The sample was originally covered with mineralization products. However, its main peculiarity resided in an almost total absence of rust. The uniqueness of such a sample imposed a non-invasive approach for its analytical study. In addition, being a singular object, in that environment, its study was considered mandatory to better understand the metallurgical skills of a copper-age community in central Italy. Thermal neutron scattering techniques have provided a wealth of information about the composition, the smelting process, and the mechanical and thermal treatments applied during the manufacture of the sample. The results obtained suggest that the sample had been treated according to the typical approach used for copper alloy smelting and smithing, i.e. cold working at room temperature and annealing at ∼700 to 800 °C.