Archaeometallurgical study of the brass cases from the Akko 1 shipwreck

摘要

The Akko 1 shipwreck is the remains of an eastern Mediterranean brig built in the first quarter of the nineteenth century, discovered in Akko harbour, Israel. During the underwater excavations (2006-2008), 158 brass cases were found, mainly between midships and the aft extremity of the shipwreck. It is suggested that they were used for artillery quills. The aim of this investigation is to determine the composition, microstructure and properties of these brass cases in order to understand their manufacturing process and to propose their possible dating and manufacturing location, and to verify their use. An archaeometallurgical analysis of selected brass cases was performed, including optical microscopy, microhardness tests and SEM including EDS. The results show that the collection was made of brass containing about 30 wt% zinc. The uniform thickness and the microstructure of the cases indicate that all artifacts were basically produced of rolled sheets and the cases were hand-made using simple tools. The metallurgical investigation suggests that they were manufactured during the first half of the nineteenth century. Combined with the archaeological evidence and the historical background, this supports the assumption that Akko 1 was a naval auxiliary vessel which was in Akko harbour circa 1840.