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Reconstructing the Arsenical Copper Production Process in Early Bronze Age Southwest Asia

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Reconstructing the Arsenical Copper Production Process in Early Bronze Age Southwest Asia Reconstructing the Arsenical Copper Production Process in Early Bronze Age Southwest Asia Loïc C. Boscher Thesis submitted to University College London For the degree of Doctor of Philosophy (PhD) UCL Qatar November 2016 2 Abstract Loïc Boscher I, Loïc Boscher, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. Date: Signed: Loïc Boscher Abstract 3 Abstract As the dominant alloy in much of the Old World for several millennia between in the Late Chalcolithic and Bronze Ages, surprisingly little work has been undertaken to understand how arsenical copper was produced and what led to its ubiquitous appearance in the archaeological record. Since arsenic and copper mineralizations often occur paragenetically, and due to the proximity of such deposits to a number of early production centres, it has often been assumed that the dominance of the alloy at the time was simply the result of the serendipitous smelting of widely available polymetallic ores. This thesis questions this narrative as overly simplistic and offers new evidence of intentional and advanced alloying techniques predating the rise of tin bronzes by several centuries. The archaeometric study of metallurgical remains from two recently excavated sites is used as the basis for the reconstruction of arsenical copper’s chaînes opératoires. The sites are Çamlıbel Tarlası in Central Turkey, dating to the mid-fourh millennium BC, and Arisman in West Central Iran, dating to the late fourth to early third millennium BC. The material under study consists of the full gamut of metal production remains, including ore minerals, crucibles, furnaces, slag, and finished objects, all of which were microscopically and compositionally characterised using optical microscopy and SEM-EDS. Other techniques, such as pXRF, EPMA, and ICP-MS were also employed to answer specific questions and in situations where the benchtop instruments were unsuitable. The overall aim of the thesis was first and foremost to evaluate ways in which arsenical copper was produced. The results demonstrate unequivocally that both naturally occurring and synthetically produced arsenic minerals were alloyed with copper in stages entirely separate from smelting. These findings are then contextualised within the wider large scale societal developments occurring at the onset of the Bronze Age by looking at the impacts of these technological innovations on the emergence of settlement specialization, the organisation of labour, and wider networks of knowledge transfer and sharing. 4 Table of Contents Loïc Boscher Table of Contents Abstract .................................................................................................................................... 3 Table of Contents ..................................................................................................................... 4 List of Figures ............................................................................................................................ 7 List of Tables ........................................................................................................................... 20 Acknowledgments .................................................................................................................. 24 Chapter 1 A Contentious Alloy ............................................................................................... 26 1.1 Introduction .................................................................................................................. 26 1.2 Current problems in our understanding of arsenical copper ....................................... 29 1.3 Archaeometallurgy as Socio-economic and Cultural Interpretative Tool .................... 34 1.4 Use of Production Remains in the Reconstruction of the Metallurgical Process......... 36 1.5 Aims of the Research .................................................................................................... 37 Chapter 2 Arsenical Copper Material Properties ................................................................... 39 2.1 Physical Properties ....................................................................................................... 39 2.2 Casting Properties ........................................................................................................ 41 2.3 Mechanical Properties .................................................................................................. 42 2.4 Volatility ....................................................................................................................... 45 2.5 Toxicity ......................................................................................................................... 48 2.6 Corrosion ...................................................................................................................... 51 Chapter 3 Arsenical Copper Production and Use ................................................................... 53 3.1 Production Technology, in Theory and Practice ........................................................... 53 3.1.1 Reduction of Copper Arsenates ............................................................................ 53 3.1.2 Co-smelting of Copper Oxides with Copper Sulfarsenides .................................... 54 3.1.3 Co-smelting of Copper Oxides with Iron Arsenides or Sulfarsenides .................... 55 3.1.4 Copper Arsenides or Arsenates to Molten Copper ............................................... 56 3.1.5 Speiss ..................................................................................................................... 58 3.1.6 Interpretative Dilemma ......................................................................................... 60 3.2 Late Chalcolithic and Early Bronze Age Use ................................................................. 63 3.2.1 Origins of Metallurgy with Comments on Colour ................................................. 63 3.2.2 Late Chalcolithic Innovations and Arsenical Copper Production .......................... 67 3.2.3 Onset of the Early Bronze Age ............................................................................... 80 Chapter 4 Çamlıbel Tarlası ...................................................................................................... 85 4.1 Geographic and Geological Context ............................................................................. 85 4.2 Archaeological Context................................................................................................. 87 Loïc Boscher Table of Contents 5 4.2.1 Chronology ............................................................................................................ 87 4.2.2 Çamlıbel Tarlası I ................................................................................................... 88 4.2.3 Çamlıbel Tarlası II .................................................................................................. 89 4.2.4 First Phase of Ephemeral Use (FPEU) .................................................................... 91 4.2.5 Çamlıbel Tarlası III ................................................................................................. 91 4.2.6 Second Phase of Ephemeral Use (SPEU) ............................................................... 93 4.2.7 Çamlıbel Tarlası IV ................................................................................................. 93 4.3 Previous and Related Research .................................................................................... 95 Chapter 5 Arisman ................................................................................................................. 96 5.1 Geographic and Geological Context............................................................................. 96 5.2 Archaeological Context .............................................................................................. 100 5.2.1 Chronology .......................................................................................................... 100 5.2.2 Arisman I Area B .................................................................................................. 102 5.2.3 Arisman I Area D ................................................................................................. 103 5.2.4 Arisman I Area C .................................................................................................. 104 5.2.5 Arisman I Area A.................................................................................................. 105 5.2.6 Arisman I Area E .................................................................................................. 107 5.3 Previous and Related Research .................................................................................. 108 Chapter 6 Methodology ....................................................................................................... 110 6.1 Sampling Strategy ...................................................................................................... 110 6.2 Optical Microscopy .................................................................................................... 111 6.3 Scanning Electron Microscopy – Energy Dispersive Spectrometry (SEM-EDS) ............... 112 6.4 Portable Hand-held X-Ray Fluorescence (pXRF) ........................................................ 116 6.5 Multicollector
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