Archives

Tempered strength: A controlled experiment assessing opportunity costs of adding temper to clay

Posted on August 30, 2017 by ARCAS

Publication date: October 2017Source:Journal of Archaeological Science, Volume 86 Author(s): Michelle Rae BebberThe addition of pottery additives (temper) provides both production-based benefits gained during the initial vessel formation phase, and performance-based benefits associated with post-firing vessel daily use. This paper presents the results of a controlled archaeological experiment designed to assess the opportunity costs associated with the addition of temper to clay during prehistoric pottery production sequences. Specifically, this study builds upon earlier research using material science methods to more broadly assess whether vessel strength is sacrificed by the addition of temper into the clay body. Standardized experimental ceramic test specimens, based directly upon petrographic analysis of archaeological samples from a regional context (South Central Ohio, USA) and produced using glacially-deposited illite-based clay, were subjected to mechanical strength tests using an Instron Series IX universal testing machine. The results demonstrate that there are indeed opportunity costs associated with temper addition: lost potential strength and reduced vessel use-life. Overall, untempered samples were significantly stronger than samples tempered with the most commonly used regional tempers—grit, limestone, and burnt shell—in terms of peak load and modulus of rupture. In other words, the results presented here suggest that prehistoric potters were losing the opportunity to create significantly stronger vessels in favor of the benefits that come with the addition of temper. Understanding of the existence, kind, and degree of opportunity costs that come with the addition of temper to clay emphasizes just how important the benefits of tempering must have been for the technology to be invented, experimented with, and ultimately so widely adopted.

Read more

Editorial Board

Posted on August 26, 2017 by ARCAS

Publication date: September 2017Source:Journal of Archaeological Science, Volume 85

Read more

Repealing the Çatalhöyük extractive metallurgy: The green, the fire and the ‘slag’

Posted on August 17, 2017 by ARCAS

Publication date: Available online 15 August 2017Source:Journal of Archaeological Science Author(s): Miljana Radivojević, Thilo Rehren, Shahina Farid, Ernst Pernicka, Duygu CamurcuoğluThe scholarly quest for the origins of metallurgy has focused on a broad region from the Balkans to Central Asia, with different scholars advocating a single origin and multiple origins, respectively. One particular find has been controversially discussed as the potentially earliest known example of copper smelting in western Eurasia, a copper ‘slag’ piece from the Late Neolithic to Chalcolithic site of Catal-hoyuk in central Turkey. Here we present a new assessment of metal making at Çatalhöyük based on the re-analysis of minerals, mineral artefacts and high-temperature materials excavated in the 1960s by J. Mellaart and first analysed by Neuninger, Pittioni and Siegl in 1964. This paper focuses on copper-based minerals, the alleged piece of metallurgical slag, and copper metal beads, and their contextual relationship to each other. It is based on new microstructural, compositional and isotopic analyses, and a careful re-examination of the fieldwork documentation and analytical data related to the c. 8500 years old high-temperature debris at Çatalhöyük. We re-interpret the sample identified earlier as metallurgical slag as incidentally fired green pigment, which was originally deposited in a burial and later affected by a destructive fire that also charred the bones of the interred body. We also re-confirm the contemporary metal beads as made from native metal. Our results provide a new and conclusive explanation of the previously contentious find, and reposition Çatalhöyük in a new narrative of the multiple origins of metallurgy in the Old World.

Read more

Provenance and recycling of ancient silver. A comment on “Iridium to provenance ancient silver” by Jonathan R. Wood*, Michael F. Charlton, Mercedes Murillo-Barroso, Marcos Martinón-Torres. J. Archaeol. Sci. 81, 1–12

Posted on August 8, 2017 by ARCAS

Publication date: Available online 7 August 2017Source:Journal of Archaeological Science Author(s): Ernst PernickaIt is argued that it is unlikely that iridium can be used as tracer for the provenance of ancient silver for geochemical reasons. Instead it is suggested that the observed low but measurable iridium concentrations may be due to silver produced from argentiferous gold by cementation. It is furthermore argued that the calculation of geological model ages from lead isotope ratios does not provide any additional information compared with the use of conventional three-isotope diagrams.

Read more

Gold parting, iridium and provenance of ancient silver: A reply to Pernicka

Posted on August 6, 2017 by ARCAS

Publication date: Available online 5 August 2017Source:Journal of Archaeological Science Author(s): Jonathan R. Wood, Michael F. Charlton, Mercedes Murillo-Barroso, Marcos Martinón-TorresWe present a detailed response to Professor Pernicka’s critique of our paper entitled “Iridium to provenance ancient silver”. We have concluded that Pernicka’s hypothesis, which suggests that elevated levels of iridium in ancient silver artefacts is a consequence of silver deriving from the cementation (parting) process, does not account for the available evidence and that his critiques of the analyses we presented seem misplaced. We offer a simpler solution and show that the structure of our transformed data is founded on logical reasoning which is borne out by the empirical results. Essentially, this response supports our view reported in the original paper that the variation in iridium in ancient silver is largely geological rather than a consequence of de-silvering gold.

Read more

Editorial Board

Posted on August 1, 2017 by ARCAS

Publication date: August 2017Source:Journal of Archaeological Science, Volume 84

Read more