6: The Chemical Study of Metals—the Medieval and Later Brass Industry in Europe
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Published:16 Dec 2016
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Special Collection: RSC eTextbook CollectionProduct Type: Textbooks
Archaeological Chemistry, The Royal Society of Chemistry, 3rd edn, 2016, vol. 3, pp. 245-295.
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This chapter reviews one particular aspect of the history of copper alloys, which is the use of brass, an alloy primarily of copper and zinc. This alloy is different from all other alloys of copper because of the volatility of zinc, which means that metallic zinc could not be directly smelted from its ore, and was therefore largely unknown in Europe until the 17th century AD. In turn, this means that brass could not be made by the direct mixing of metallic copper and zinc. The Romans employed an indirect method of manufacturing brass called the calamine process, in which metallic copper is heated with zinc ore in a closed crucible. Between about 900 and 1000 °C, the zinc vapour enters the hot copper by diffusion, to produce brass, the zinc content of which is practically limited by the process. This method appears to have its origins somewhere in Anatolia, Iran or Central Asia during the 2nd millennium BC. The bulk of this chapter focuses on the production of brass in Medieval and later England and Europe, with examples given of the analysis of jettons (tokens similar to coinage) and scientific instruments. The chapter ends with a discussion of the identification of imported copper and brass in early contact North America.