On the making of copper oxhide ingots: evidence from metallography and casting experiments

We report on the texture, phase content and on the making of Late Bronze Age copper oxhide ingots as excavated from the shipwreck of Uluburun. This type of ingot represented the world market bulk metal in the Mediterranean and beyond. The ingots are characterized by a high porosity, by inclusions of slag fragments and cuprite which result from casting raw copper smelted before from ores. The ingots were cast from several batches of copper. The shape of the oxhide ingots was never fully understood, and the way of casting was uncertain due to the absence of casting moulds. It is the aim of this paper to discuss the making of these ingots. We will present an alternative model on how to cast such ingots using four crucibles. The experiments will show that the texture of the ingots is created by gases such as hydrogen, carbon monoxide and water vapour. The high porosity is shown to be advantageous for breaking the ingots into fragments.