Glass Making in the Greco-Roman World Studies in Archaeological Sciences 4 The series Studies in Archaeological Sciences presents state-of-the-art methodological, technical or material science contributions to Archaeological Sciences. The series aims to reconstruct the integrated story of human and material culture through time and testifies to the necessity of inter- and multidisciplinary research in cultural heritage studies. Editor-in-Chief Prof. Patrick Degryse, Centre for Archaeological Sciences, KU Leuven, Belgium Editorial Board Prof. Ian Freestone, Cardiff Department of Archaeology, Cardiff University, United Kingdom Prof. Carl Knappett, Department of Art, University of Toronto, Canada Prof. Andrew Shortland, Centre for Archaeological and Forensic Analysis, Cranfield University, United Kingdom Prof. Manuel Sintubin, Department of Earth & Environmental Sciences, KU Leuven, Belgium Prof. Marc Waelkens, Centre for Archaeological Sciences, KU Leuven, Belgium Glass Making in the Greco-Roman World Results of the ARCHGLASS Project Edited by Patrick Degryse Leuven University Press Published with support of © 2014 by Leuven University Press / Presses Universitaires de Louvain / Universitaire Pers Leuven. Minderbroedersstraat 4, B-3000 Leuven (Belgium). All rights reserved. Except in those cases expressly determined by law, no part of this publication may be multiplied, saved in an automated datafile or made public in any way whatsoever without the express prior written consent of the publishers. ISBN 978 94 6270 007 9 D / 2014 / 1869 / 86 NUR: 682/933 Lay-out: Friedemann Vervoort Cover: Jurgen Leemans 5 Preface The ARCHGLASS “Archaeometry and Archaeology of Ancient Glass Production as a Source for Ancient Technology and Trade of Raw Materials” project, is a Seventh Framework Programme “Ideas” project funded under the European Research Council Starting Grant scheme. The main goals of the project were to develop innovative archaeometrical techniques to reconstruct ancient economies, and to apply these methods to gain new insights in the trade and processing of mineral raw materials used for glass making. In effect, the project and this book presents a database of mineralogical and chemical compositions of possible raw materials (sand and flux) for primary glass making. From these data, the primary provenance of ancient natron glass can be derived. The focus of this project was on the Hellenistic-Roman world, investigating both production and consumer sites of glass from a chemical perspective, but integrating typo-chronological and archaeometrical information. Analyses of glass artefacts at consumer sites as well as a chemical characterisation of raw glass at primary production sites are presented. Using an interdisciplinary approach, combining historical, archaeological and archaeo- metrical data, the occurrence of primary production centres of raw glass outside those known from archaeological excavation in Syro-Palestine and Egypt were investigated. In particular, the western Mediterranean area including the regions of Italy, Gaul, Spain (described by ancient authors as primary glass producers) and north-Africa were investigated. In this way, by developing new analysis techniques, an innovative archaeological interpretation of glass trade in the Hellenistic-Roman world can be given, and the possibility of integrating glass studies into the larger framework of Roman economy studies, now underrepresented, becomes possible. The political situation in Northern Africa and the Middle East during the course of the project prohibited much fieldwork there. Only a small amount of samples from Israel, Egypt, Libya and Tunisia from previous field campaigns and from older, well- documented collections were studied. This makes the study of North Africa as a supplier of natron glass more difficult. Moreover, a database of analyses of possible raw materials and glass is never complete. The approach to the geological materials analysed here is based on regional survey, taking samples from different geological hinterlands with a wide spacing, but not going into very detailed sampling grids. Nevertheless, almost 300 samples of sand and flux and close to 400 analyses of glass are taken into account in this book. This analytical strategy makes the interpretation of provenance given in this book the best possible interpretation to the knowledge of the authors, at this point in time within the current state-of-the-art. The reconstruction of the primary origin of ancient natron glass presented here, hence refers to broad geological/geographical regions where glass was (likely) made, rather than to individual sites. The authors wish to make all this raw data available in open access format to all scholars in the field, to use in their own research, study or teaching… and judge for themselves. This book is written with archaeologists and historians in mind. The analysis procedures, for instance the newly developed methods of isotopic analysis, can be found in specialised journal papers. This 6 Preface book focuses on an archaeological interpretation of the exact data produced, especially in the conclusions at the end of each chapter, and the discussion in chapters six and seven. 7 Acknowledgements Several museums, excavations and individual scholars provided samples and unravelled archaeological contexts for this study, for which we would like thank Lorenzo Appolonia, Rossella Arletti, Nizar Abu Jaber, Adam Aja, Bob Brill, Nick Cahill, Giacomo Chiari, Peter Cosyns, Wim Dijkman, Roald Doctor, Elizabetha Dotsika, Susanne Ebbinghaus, Danielle Foy, Patrizia Framarin, Ian Freestone, Caroline Jackson, Filomena Gallo, Domingo Gimeno-Torrez, Bernard Gratuze, Joe Greene, Hans Huismans, Susanna ‘Suzy’ Kirk, Roland Lamprichs, Veerle Lauwers, Marleen Martens, David Mattingly, Judith McKenzie, Luigia Melillo, Piero Mirti, Gianmario Molin, Patrick Monsieur, M. Pugès, Ziad al Saad, Mariarosa Salvatore, Valeria Sampaolo, Alberta Silvestri, Sofie Vanhoutte, Frank Vermeulen, Michael Vickers, Susan Walker, Erik Wetzels, the Sagalassos Archaeological Research Project, the Servei d’Arqueologia Urbana, Ajuntament (municipality) of Barcelona, the Getty Museum, the Getty Conservation Institute, the Harvard Art Museums, Harvard Semitic Museum. Femke Hasendonckx, Leander Geldhof, Maarten Diels were active as master students in this project. Elvira Vassilieva, Kris Latruwe, Steven Luypaers, Rita Giannini, Lieve Balcaen, Johan Honings and Kelly Domoney were essential for analytical support and interpretation of data. Ian Freestone, Marie Dominique Nenna, Thilo Rehren, Frank Vanhaecke and Caroline Jackson are greatly acknowledged for feedback on ideas and discussions. Udo Haack, Jens Schneider and Philippe Muchez were essential in the design and development of this project, while Dennis Braekmans, Katherine Eremin, Andrew Shortland and Marc Walton have been friends, colleagues and compagnons de route, for which I cannot thank them enough. Funding for this project was provided by several projects of the Fund for Scientific Research Flanders (FWO, G.002111.N, G-08-00291, G.A078.11), the KU Leuven (PFV/10/001) and the European Research Council under the Starting Grant scheme (grant agreement no. 240750). Annelore Blomme, Dieter Brems and Monica Ganio benefitted from a Research Assistant Grant of the Fund for Scientific Research—Flanders (FWO-Vlaanderen). Dieter Brems is currently working as postdoctoral fellow of the Fund for Scientific Research— Flanders (FWO-Vlaanderen). ERC allowed the training of a significant number of scholars, who will undoubtedly find their way into the international community in their research field. 9 Table of Contents List of illustrations 11 List of Tables 13 Chapter 1 The archaeology and archaeometry of natron glass making R.B. Scott, P. Degryse 15 Chapter 2 Western Mediterranean sands for ancient glass making D. Brems, P. Degryse 27 Chapter 3 The Sr-Nd isotopic fingerprint of sand raw materials D. Brems, M. Ganio, P. Degryse 51 Chapter 4 Trace elements in sand raw materials D. Brems, P. Degryse 69 Chapter 5 The Sources of Natron V. Devulder, P. Degryse 87 Chapter 6 Primary glass factories around the Mediterranean P. Degryse, M. Ganio, S. Boyen, A. Blomme, B. Scott, D. Brems, M. Carremans, J. Honings, T. Fenn, F. Cattin 97 Chapter 7 Conclusions P. Degryse 113 10 Table of Contents Appendix A Sampling locations, elemental compositions of the analysed sand samples as determined by ICP–OES analysis, LOI results, results of the Sr and Nd isotopic analysis and trace element analysis results. 120 Appendix B Calculated glass compositions after raising the Na2O levels of the sands to 16.63%, the average Na2O content of Roman natron glass (Foster and Jackson, 2009). 156 Appendix C Calculated glass compositions after raising the CaO levels of the sands containing insufficient lime to 7.48%, the average CaO content of Roman natron glass (Foster and Jackson, 2009). 168 Appendix D http://ees.kuleuven.be/geology/archaeometry/index.html 171 References 173 11 List of illustrations Figure 2.1: Schematic representation of the method used to calculate the composition of glass that can be produced from the analysed beach sands after the addition of pure Na2O to the glass batch. 29 Figure 2.2: Schematic representation of the method used to calculate the composition of glass that can be produced from the analysed beach sands after the addition of Na2O and extra CaO to the glass batch. 30 Figure 2.3: Histograms showing the elemental composition of hypothetical glasses that