Archaeometallurgy of copper in the Middle Elamite period of southwestern Iran: Analytical investigation of various parts of the copper production in Haft Tappeh

Abstract

The Elamite period (ca. 3000 to 640 BC) hosts one of the earliest kingdoms to arise on the Iranian Plateau, and its metallurgy displays significant technical and industrial sophistication in comparison with the prehistoric period industries in other regions of Iran. This paper presents results of an analytical study of different metallurgical materials from the important Middle Elamite site of Haft Tappeh (ca. 1400 BC), including slags, metallic ingots/prills and objects. The samples were analysed by chemical and microanalytical methods including, ICP-OES, SEM-EDS, WD-XRF, EPMA and thin section petrography. Based on the results, the primary copper smelting process applied at Haft Tappeh was apartially incomplete smeltingprocess that may be interpreted as a two-step procedure, including partial smelting of copper from sulphidic ores leading to matte production and refining the copper ingots/prills to obtain metallic copper. Also, the cementation of copper and cassiterite was the main process used to make tin bronze ingots/prills; however, for producing bronze, the ancient Elamite metalworkers might have known the direct smelting of mixed copper-tin ores as well. A third technique used at Haft Tappeh was the manufacturing of different, small objects made of impure copper and/or tin bronze. Thus, it is probable to introduce the copper-base metallurgy in Haft Tappeh as three main stages including copper smelting from sulphidic copper ores, the refining of early copper ingots/prills and production of tin bronze in different ways.