A metallographic study of objects and fragments from the site of Igbo Isaiah, Igbo-Ukwu, Nigeria

Abstract

• This work presents a new analytical and metallographic examination of fragmentary objects and components from Igbo-Ukwu, eastern Nigeria dating to approximately the ninth to twelfth centuries AD. These objects are thought to be part of the early accidental discoveries within the compound of Isaiah Anozie, collected in 1939 by the local District Officer, Frank Carpenter, in Igbo-Ukwu. As such, they pre-date the excavations undertaken by Thurstan Shaw and his team in 1959–1960 and 1964, and therefore have no primary archaeological context. The accidental and excavated finds from the site of Igbo Isaiah formed part of the contents of what is believed to be a storeroom for regalia. Previous analytical and metallographic studies on the copper alloy objects from Igbo-Ukwu have concluded that they were predominantly lost-wax (cire perdue) castings of bronze or leaded bronze. The present study establishes that while some of the fragmentary objects were cast, many of the components of composite objects, including wires, twisted handles, chain links, and bosses (spiral ornaments), had been expertly hammered into shape and annealed. Furthermore, the hammered items tended to be unalloyed copper whereas the cast objects were alloyed metal. This demonstrates that the Igbo-Ukwu smiths were fully aware of the properties of the metals they were using and made careful decisions about the selection of these metals and the choice of techniques used to produce specific objects and/or components. The trace element composition of the pieces indicates that most of the metal is likely to have come from the nearby source at Abakaliki.