Iron Age tin bronze metallurgy at Marlik, Northern Iran: an analytical investigation

• Published in: Archaeological and anthropological sciences 2017-03, Vol.9 (2), p.233-249
• Main Authors: Oudbashi, Omid, Hessari, Morteza
• Format: Article
• Language: English
• Subjects: Anthropology; Archaeology; Arkeologi; Chemistry/Food Science; Copper; Earth and Environmental Science; Earth Sciences; Excavation; Geography; Grain; ICP-MS; Iron Age; Life Sciences; Light microscopy; Marlik; Mass spectrometry; Metallurgi och metalliska material; Metallurgy; Metallurgy and Metallic Materials; Microstructure; Original Paper; SEM-EDS; Silver; Smelting; Spectrometry; Sulfides; Sulphidic inclusions; Tin; Tin bronze; X-ray spectroscopy
• ISSN: 1866-9557; 1866-9565; 1866-9565
• DOI: 10.1007/s12520-015-0280-1

The archaeological excavations performed in 1961 and 1962 at the necropolis of Marlik (Gilan District, northern Iran) revealed important archaeological remains dating to Iron Age I and II periods (late second/early first millennium BCE). While the metal collection from Marlik includes various gold, silver and bronze objects and is considered one of the most significant finds of metal objects from the prehistoric Iran, the technological investigations discussed in this paper provide information on tin bronze objects only from Marlik. Both the composition and the microstructure of 25 copper alloy objects have been determined in order to achieve a better understanding of the metallurgical processes used in northern Iran from the second to the first millennium BCE. Experimental analyses were carried out using inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and optical microscopy. The results demonstrated that the copper-base objects were made of the binary copper–tin alloy with variable tin contents. Other elements such as As, Ni, Pb, Zn and Sb were detected in minor/trace amounts. Variable tin content may be due to the application of an uncontrolled procedure to produce bronze alloy (e.g. co-smelting or cementation). Microscopic observations and microanalyses revealed the presence of numerous copper sulphide inclusions, lead globules and intermetallic phases scattered in the bronze solid solution. The microstructures seen in the bronze objects under study were varied and included worked/annealed or dendritic grain structures.