Metals & Giants

Since May 2024, a project has been underway at CEZA that investigates the origin of the copper used in bronzes from the Late Nordic Bronze Age in Denmark and the Nuragic period in Sardinia. Funded for three years by the Danish Augustinus Foundation, the Metals & Giants project is led by Helle Vandkilde, Mats K. Holst and Gianfranca Salis and conducted and coordinated by the Moesgård Museum in Aarhus. In addition to archaeological and geological components, this interdisciplinary project includes an archaeometallurgical part carried out at CEZA under the direction of Daniel Berger as a project partner.

The project links two regions of Europe that are not only geographically but also culturally far apart. Around 1000 BCE, Denmark belonged to the Late Bronze Age Nordic sphere, known as the Nordic Bronze Age, while Sardinia was characterised by the Nuragic culture, noted for its monumental architecture (“nuraghi”) and impressive stone statues. While culturally very distinct, a few years ago Helle Vandkilde and colleagues observed striking similarities, most notably iconographic depictions of warriors wearing horned helmets. These conspicuous features led to the hypothesis that, despite their differences, close connections may have existed between the two regions—connections possibly rooted in economic exchange. The slogan “Metals for Amber,” coined by Vandkilde, captures the essence of this idea: Nordic Bronze Age societies may have imported copper from Sardinia in exchange for Baltic amber and other goods.

It is generally known that Denmark and other regions of the Nordic Bronze Age depended on external copper resources, as either no local deposits existed or they had not yet been exploited. From as early as around 1800 BCE, Nordic communities obtained copper from various parts of Europe—including Great Britain, the Alpine region, and the Slovak Ore Mountains—to satisfy their metal demands. From about 1200 BCE onward, Sardinia may have become an additional supplier and trade partner. However, concretely proving Sardinia as a copper source is especially difficult. Typically, both chemical composition and lead isotope ratios help to pinpoint origin, but in Sardinia’s case, the signatures overlap significantly with those of other potential source regions (e.g., the southern Alps, Iberian Peninsula) that excluding other sources is not possible. Moreover, the relatively modest yield of Sardinian copper ore makes northern export somewhat unlikely. Nonetheless, earlier analyses hinted that Sardinian copper might have been used—an issue now being systematically investigated within the Metals & Giants project.

Two central lines of research

The project pursues two main lines of research. First, through archaeological and geological fieldwork in Sardinia’s interior and analyses of metal objects, the project aims to better understand the exploitation of local copper and lead ores as well as indigenous metallurgy. Excavations at the Sardinian sanctuary of Matzanni, which may have played a key role in controlling metal resources, are complemented by analyses of raw metal ingots and finished objects at CEZA. These rely on conventional X-ray fluorescence and lead isotope analysis, but are supplemented by a novel approach: for the first time, osmium isotope ratios are being measured in copper objects—a method previously used only in provenance studies of iron. Initial analyses of Sardinian bronze figurines and copper ingots, combined with lead, tin, and copper isotope analyses, have yielded promising results. Some objects exhibit highly radiogenic osmium isotope ratios—a feature that appears characteristic of Sardinian copper ores and suggests the use of local resources. Until now, this could not be conclusively demonstrated due to ambiguous lead isotope ratios and high lead content. Other objects, however, show significantly less radiogenic osmium ratios, pointing to other sources. In these cases, the lead isotope ratios suggest an origin of the copper on the Iberian Peninsula. This indicates that Sardinia used both local and imported copper resources, which were sometimes or regularly mixed. Further systematic sampling and analysis using this innovative multiproxy approach over the next few years aim to clarify the relative contribution of local versus external resources to Sardinian metal production.

The second research strand focuses on metal objects from the Late Nordic Bronze Age in Denmark. These are being analysed at CEZA using the same methodological approach, with the goal of identifying Sardinian copper among the spectrum of possible sources. The analyses of Sardinian reference materials are crucial for interpreting the Nordic finds. Should copper from Sardinia be identifiable via its characteristic osmium isotope ratios, this would represent a significant step toward reconstructing the connections between these two cultural regions and their potential long-distance trade relationships.

First publication in PLOS One

The first results of the project will be published in the journal PLOS One in 2025, under the title: Daniel Berger, Valentina Matta, Nicola Ialongo, Heide W. Nørgaard, Gianfranca Salis, Michael Brauns, Mats K. Holst, Helle Vandkilde, Multiproxy analysis unwraps origin and fabrication biographies of Sardinian figurines: On the trail of metal-driven interaction and mixing practises in the early first millennium BCE.