image/svg+xml137 VIII/2/2017 INTERDISCIPLINARIA ARCHAEOLOGICA NATURAL SCIENCES IN ARCHAEOLOGY homepage: http://www.iansa.eu Analytical Assessment of Chaltasian Slag: Evidence of Early Copper Production in the Central Plateau of Iran Bita Sodaei a* , Poorya Kashani b a Department of Archaeology, Varamin-Pishva Branch, Islamic Azad University, Tehran, Iran b Archaeological Services Incorporations, Toronto, Canada 1. Introduction The Iranian Central Plateau is located between the Southern Alborz Mountain and the Central Iranian desert and most of the fertile plains are located between the two above areas (Figure 1) (Fazeli Nashli 2013). The study of ancient slag material plays a signifcant role in understanding old metallurgy. The discovery of slag remains from several sites in the Central Plateau in the 4 th Millennium BC has been an important clue to prove the utilization of smelting processes. These initial developments were centred on metallurgical-rich regions on the Iranian Plateau (Pigott 2004): Tappeh Sialk, Tal-I Iblis, Tappeh Ghabristan, Arisman, Tappeh Zaqeh (Pernicka 2004a; 2004b; Nezafati, Pernicka 2006), Tepe Hissar and Hassanlo (Thornton et al. 2009). The existence of slag material in Chaltasian shows that the site can fall into the same category in the Early First Millennium BC. Chaltasian is an Iron Age II site, situated in the Asgariyeh Rural District, Central District of Pishva County, Tehran Province. The area of this site during the Iron Age I period was 6500 m 2 (Figure 2). The frst season of excavation at Tappeh Chaltasian was conducted by the Varamin-Pishva Branch of the Islamic Azad University under the supervision of Rouhollah Yousef Zoshk from September to December 2012 (Yousef Zoshk 2012). The Chaltasian area is located on the western edge of the city of Pishva, about 5 km away (Figure 3).GPS coordinates for the site’s centre (datum point) are N: 3519176, E: 0514135, with a height of 941 metres asl. and 5 metres above ground level. During the excavation season, two units were dug out; a 2.5 by 2.5 metre unit in the central mound and a 1.5 by 1.5 metre unit in the east mound (Figures 4 and 5) (Yousef Zoshk 2012).Slag is defned as the vitrifed waste products of pyro- technological practices. Generally speaking, they are composed of the glassy, solidifed melt of reacted ore and gangue minerals, and fuel ash, as well as anything else which had been added to the smelt (Hauptmann 2007). Archaeometallurgy can determine old casting methods and metalworking. It can also give us access to the cultural and social norms that shaped technological practices and, perhaps, to the cognitive structures that created such norms (Smith 1965; 1978). Analytical research on ancient metals Volume VIII ● Issue 2/2017 ● Pages 137–144 *Corresponding author. E-mail: sodaei@iauvaramin.ac.ir ARTICLE INFO Article history Received: 8 th June 2017Accepted: 14 th November 2017 DOI: http://dx.doi.org/ 10.24916/iansa.2017.2.3 Key words: slagarchaeometallurgyChaltasianX-Ray Flourescence (XRF)polarized light ABSTRACT This study reports the archaeometallurgical analyses results on six slag remains obtained from Chaltasian, Iron Age II, in the Central Plateau of Iran, excavated by Islamic Azad University, Varamin-Pishva Branch. Metallurgical studies were carried out to identify oxides, Ca-rich silicates and metallic phases in the slag material, using wavelength dispersive X-Ray fuorescence (WDXRF), followed by an analysis of one sample under the polarizing microscope: plane polarized light (PPL) and cross polarized light (XPL). Based on the analyses, it has been concluded that these six copper slag remains have a considerable amount of silica, which had been added to the smelt to increase its fuidity. Analyses showed a clinopyroxene microstructure in a glassy matrix for fve samples, and a barite source, from a probable lead-zinc source in limestone, for the other sample. The absence of arsenic in these copper slags could show a paradigm shift in copper production in this space-time grid. According to the low amount of slag present on site, on the one hand, and the application of relatively advanced extraction technology on the other, this research introduces Chaltasian as an Iron Age II small copper production centre in the Central Plateau of Iran with a locally-developed copper extraction technology.
image/svg+xmlIANSA 2017 ● VIII/2 ● 137–144 Bita Sodaei, Poory Kashani: Analytical Assessment of Chaltasian Slag: Evidence of Early Copper Production in the Central Plateau of Iran 138