The Brass Nails of the Akko Tower Wreck (Israel): Archaeometallurgical Analyses

Abstract

The shipwreck designated as the Akko Tower Wreck was discovered inside Akko harbor, Israel, in 1966. It was surveyed in 1975 and 1981, and excavated in 2012–2013. Hull planks were connected to the frames by brass nails, some of which were in situ, emerging vertically from the planking, where frames had disappeared, and others were detached. The 105 nails that were retrieved were tentatively divided into two groups (A and B) according to their general shape and size. Nails sampled from each group were characterized by non-destructive and destructive metallurgical methods, including XRF, light microscopy, SEM–EDS, microindentation hardness measurements, and lead isotope analysis, in order to reveal their composition and microstructure, as well as to determine their manufacturing process and date the origin of the raw material. All nails were manufactured by casting and made of binary copper-zinc alloy: Type A with 35–36 wt% zinc, and Type B with 33–34 wt% zinc (XRF results). These compositions confirmed the preliminary typing of the nails. Their microstructure indicates that they were manufactured differently: Type A nails have Widmanstätten thin lamellae plates, and Type B nails have α-brass grains containing a dendritic microstructure. Based on their zinc and lead concentrations it is suggested that the nails were manufactured in the first half of the nineteenth century. The lead isotope analyses of the nails suggest that the raw material most probably originated in Great Britain. Hence, it is suggested that the Akko Tower Wreck is the remains of a European merchantman which sank in Akko harbor about the middle of the nineteenth century.