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In the Bronze Age, the so-called Nuraghe culture flourished in Sardinia. A culture that is known for tower-like stone constructions, nuraghers, and for the small bronze figures, bronzetti, which often depict warriors, gods and animals. These figures have fascinated scientists, but their exact metallic origins have been unknown.

To find out where the copper in these figures came from, the research team used a new scientific method called a multi-proxy approach (a combination of different chemical analyses). Here, they compared isotopes of copper, tin, lead and a rarer isotope called osmium to get a clearer picture of the origin of the metals. The method, developed at the Curt-Engelhorn Center for Archaeometry in Mannheim, has made it possible to solve a puzzle that has puzzled researchers for years.

"The results show that bronzetti was primarily made from copper from Sardinia, sometimes mixed with copper from the Iberian Peninsula (modern-day Spain and Portugal). The study also revealed that copper from the Levant—places like Timna in Israel and Faynan in Jordan—was not used in Sardinia, which was only made clear by looking at osmium isotopes," says first author Daniel Berger from the Curt-Engelhorn Center for Archaeometry, who developed the new method, performed the analyses and provided the basic interpretation.

The research is in the journal PLOS One.

Collaboration between natural science and archaeology

While Daniel Berger emphasizes how the new method of isotope analyses provides a clear picture of the geographical origin of copper, Helle Vandkilde points to the collaboration between natural science and archaeology.

"Archaeological methods establish a strong foundation that the latest scientific methods can refine and explain. This will bring old discussions to an end. In our case, the very latest geochemical knowledge points to the origin of the metal in specific geographical areas and certain mines. It is also possible in several cases to trace a strategic mix of copper with different origins, presumably to achieve certain effects such as the product's color and strength," says Professor Helle Vandkilde from Aarhus University.

The researchers also examined three of the largest Nuraghian shrines, all of which produced bronzetti, and discovered that the metal used at each site was very similar. This suggests that there was a common approach to the production of these objects throughout the island.

According to the research group, it is interesting that although Sardinia has local sources of tin and lead, they were not used in the figurines. The tin to be used to make bronze must have been imported, probably from the Iberian Peninsula, based on the isotope signatures of bronzetti and the chemical patterns of Sardinian tin objects.

"Having the opportunity to analyze the famous bronze figures from Sardinia is an important step towards understanding how the island was a central piece of the metal trade during the Bronze Age. The shape and execution of the figures fit into the material culture of the period, and yet they contain stylistic features that feel amazingly familiar to us in southern Scandinavia.

"We only have to think of the Viksø helmets or the warriors on our petroglyphs wearing helmets adorned with horns. With new knowledge about where the metal for these figures came from, we are now one step closer to mapping the connections between Sardinia and Scandinavia," says Associate Professor at Moesgaard Heide Wrobel Nørgaard.

A Nordic connection

Field studies in collaboration between Aarhus University and Moesgaard Museum have demonstrated hitherto unknown connections between Sardinia and the Nordic countries in the Bronze Age 1000–800 BC.

Iconic horned helmets, which we know from Viksø, Kallerup, Grevensvænge and Tanum, also appear in Sardinia, both in miniature and giant formats. In both places, these unique horn-helmeted figures are found.