BMCR 2001.08.10

King Croesus’ Gold: Excavations at Sardis and the History of Gold Refining. Archaeological Exploration of Sardis, 11

, , King Croesus' gold : excavations at Sardis and the history of gold refining. Archaeological exploration of Sardis ; 11. Cambridge, MA: Archaeological Exploration of Sardis, Harvard University Art Museums, in association with the British Museum Press, 2000. 272 pages : illustrations (some color), maps ; 29 cm.. ISBN 0674503708. $75.00.

The goldworking area of Sardis and the significance of goldworking in the Lydian kingdom, as well as the ancient world in general, have been of interest to many scholars. The historical context and location of Sardis make it a pivotal site, of interest to Near Eastern and Classical historians and philologists. Those involved in numismatics and metallurgy have been especially concerned about the recovery of the Sardis workshop, since the first bimetallic system of coinage has been attributed to Croesus, king of Sardis from 561-547 B.C. The authors and contributors of King Croesus’ Gold have now provided a comprehensive exposition of the excavation of the gold workshop at Pactolus North (Sardis), and the theories and facts behind the processes used to refine gold. Included in this most impressive book are the examination of ancient, medieval, and modern methods of refining gold, and scientific examination of numerous finds from Sardis as well as Lydian electrum, gold, and silver coinages.

King Croesus’ Gold begins with a prologue (Ramage and Craddock) introducing the reader to the Sardis excavation of the refinery, with a brief explanation of the processes involved in refining gold and silver, most notably cementation (a parting process that separates the silver from the gold in a gold-silver alloy) and cupellation (a process that separates the silver from the smelting remains); more technical discussions are found in later chapters and the appendices. The first portion of the book, Chapters 1-4, sets the stage and introduces the reader to the relevant background information needed to understand the refining process and the remains found at Sardis. Chapter 1, “Golden Sardis” (Ramage), focuses on Sardis and its long association with gold, concluding with a short introduction to the excavation history. Chapters 2 and 3 (Craddock) are concerned with the history of gold refining around the world, as expressed in the literature of different cultures: Chapter 2 presents literary evidence from around the world, including Europe before 1500 A.D.; Chapter 3 focuses on Europe after 1500 A.D. Chapter 4 (Ramage) describes the excavation of the gold-working area at Sardis and the associated finds.

The second portion of the book focuses on the refining processes themselves. Chapters 5-9 discuss the scientific examination of the finds and the experiments undertaken to replicate the refining process used at Sardis: Chapter 5, “Scanning Electron Microscopy of the Refractory Remains and the Gold” (Meeks); Chapter 6, “Scientific Examination of Some Ceramic Materials and Samples of Litharge” (Middleton, Hook, and Humphrey); Chapter 7, “Scientific Examination of the Lydian Precious Metal Coinages” (Cowell and Hyne); Chapter 8, “Replication Experiments and the Chemistry of Gold Refining” (Craddock); Chapter 9, “Examination of the Sardis Gold and the Replication Experiments” (Gec,kinli, Ă–zbal, Craddock, and Meeks).

Chapter 10 (Craddock) pulls together the evidence of the previous chapters and describes the particular processes likely to have been used to refine gold at Sardis. The epilogue, “The Significance of the Sardis Refinery in the Classical World”, places the gold workshop and its function in the larger historical context of the mid-1st millennium B.C. Appendices 1-6 offer further technical information, as does the Technical Glossary. The bibliography presents a useful resource for further research.

Particularly impressive is the ease with which the complexities of chemical refining reactions are made accessible to those of us who have not seen a chemical formula since high school. Indeed, the summaries at the end of each chapter express in straight-forward terminology the results of microscopic examinations, chemical reactions, and replication experiments. Thus, the non-specialist can clearly understand the step-by-step discovery and explanation of the processes used to refine gold in the Pactolus North workshop. As becomes clear through the presentation of archaeological and textual data, the evidence points to the use of a type of salt cementation to refine gold at Sardis. In this procedure, common salt (possibly mixed with a carrier such as brick dust) was layered with thinly hammered gold foil or gold grains in a lidded earthenware pot (such as a cooking pot). The pot was placed in the centre of a furnace, with wood for the fire surrounding the pot in order to provide an even heat. The temperatures used were found to be on the low side, between about 600-800 degrees Celsius; this range allowed the production of gaseous chlorine, which attacked the silver and other metals in the gold. Much of the silver was bound into silver chloride, which then seeped into the pot walls and furnace bricks, to be later recovered by cupellation.

Beyond the evident relevance of understanding the process of gold refining, the authors use the evidence from Sardis to provide a context for the gold workshop, including the date of the refinery operations and the probable motive for undertaking large-scale refining of gold. In Chapter 2, Craddock points out that the processes involved in the purification of gold were known long before the floruit of the Sardis workshop; some ancient gold artifacts, such as the chisels from Ur (3rd millennium B.C.), show evidence of surface enhancement (i.e., the artifact made of natural gold alloy underwent partial processing, resulting in a thin layer of purified gold on the surface of the object, a typing of gilding). Thus, the surface would gain more golden colour, without the object losing weight or size. The refinery at Sardis, on the other hand, was involved in the complete purification of bulk gold. Ramage dates the key period of use for this industrial enterprise to ca. 575-550 BC. The workshop is itself associated with a contemporary altar dedicated to Kybele; pottery associated with the altar can be generally dated to the late 7th-early 6th centuries B.C., and two figural pottery fragments can be dated to ca. 575 B.C. Pottery from the workshop area itself has been dated by Ramage to the mid-6th century B.C.

Craddock notes: “Our idea of pure gold as a single and precisely defined element is based on the relatively modern scientific concepts of the nature of elements…, but the ancients did not have such a concept of an ultimate, pure elemental material. Thus metals such as gold, coming from various sources, could have widely differing properties but still be gold” (p. 31). Given that the knowledge of how to purify gold goes back much further than the installations at Pactolus North, what could have triggered the perceived need for bulk purification, when natural gold had previously sufficed? The answer lies in the advent of coinage, as the authors make clear. The consistency of the composition of the Lydian electrum coins tested for this publication indicates that control of the quality of the electrum coins was of great importance (Cowell and Hyne). The relative percentages of gold and silver in natural gold could vary significantly, although generally natural gold from the Pactolus is thought to contain in the region of 17-30% silver; the Lydian electrum coins consistently tested at about 55% gold and 45% silver, with minor amounts of copper. The most likely means of maintaining such consistency is by the addition of silver to the natural gold until the desired quality is attained. Ramage and Craddock note that the quality of separate coins of pure gold and silver would be much easier to control. Croesus is commonly (although not unanimously) credited with issuing the first bimetallic series of coinage, the Croeseids, and the date assigned to the refinery coincides nicely with his reign. Although the refinery was not associated with a mint (or other end-product workshop), the desire to control the coinages issued could have indeed played a pivotal role in the establishment of a gold refinery such as the Sardis refinery.

The authors of King Croesus’ Gold are to be commended for their ability to draw together a number of experts who are able to present their findings in a way that provides consistency throughout the book and makes it a pleasure to read. The organization of the volume generally provides easy access to topics, data, and sources. (Chapter 4, on the finds at the refinery, might have been better placed if it had followed chapter 1 directly, which introduces the Sardis-gold connection. As it is, it is separated from the first chapter by two chapters on the literary sources concerning gold refining.) Endnotes are located at the end of each individual chapter, removing the necessity of constantly turning to the end of the book and finding the appropriate notes for that chapter. Numerous illustrations, both colour and black-and-white, further enhance the text.

This book is a valuable resource for anyone interested in Sardis, ancient coinages, or the refining of gold in the ancient world. It is a welcome addition to the Archaeological Exploration of Sardis publications.