Characterization of an Ancient Bimetallic Alloy from Moche Civilization (Peru).

The Moche civilization in Peru developed marvelous metallurgy, primarily using alloys of gold, copper and silver, with the most famous of them called Tumbaga, which resembles pure gold after a depletion process on its surface. However, they also created objects with more standard single-layer alloys or gilding. To distinguish between these techniques in a non-destructive manner is essential. Here, we analyzed a thigh protector, composed of two parts, one seemingly in silver and the other seemingly in gold. The sample was analyzed using X-ray fluorescence measurements integrated with Monte Carlo simulation. The results show that the silver part is formed of a silver-based alloy covered in a corrosion layer, while the gold part is made of Tumbaga. Moreover, for the first time, the gold profiles of different Tumbaga gold objects, from the same burial, were compared, allowing us to obtain information about the standardization of their manufacture.

Characterization of a Unique Nuragic Bronze Navicella with a Combination of X-ray Fluorescence Spectrometry and Monte Carlo Simulation.

This paper describes the results obtained from an archaeometric study of a bronze Nuragic small boat model (Sardinia, Italy) dating from the Early Iron Age (presumably 9th-7th centuries BC). The artifact comes from an unknown location in Sardinia and is one of the objects that came to the Museum of Turin in the 19th century. This model is of particular interest as it is a unique Nuragic boat model containing a human figure among its decorations. The artifact is kept in the collection of the Royal Museum of Turin (Italy) and is a typical example of Sardinian manufacture from the Early Iron Age. This study was carried out using a combination of non-invasive techniques with energy dispersive X-ray fluorescence spectrometry (ED-XRF) integrated with Monte Carlo (MC) simulations and Raman spectroscopy, which allowed the characterization of the alloy of the artifact.

Combining X-ray Fluorescence and Monte Carlo Simulation Methods to Differentiate between Tumbaga and Gold-Alloy or Gildings.

Depleted metals have been produced since many centuries ago. Probably the most famous examples from ancient times are the so-called Tumbaga gold artifacts, whose production was introduced by the pre-Colombian civilizations. Tumbaga-like structures have been identified also in modern nanotechnological materials. In both cases, but specially for the ancient Tumbaga, due to their preciousness, their characterization should be obtained by non-destructive analysis. Several analytical protocols have been developed, some of them non-destructive, such as those based on X-ray Fluorescence, but the results obtained do not always allow for a reliable identification of Tumbaga with respect to gilding or single alloy samples. Besides the capability to distinguish between different structures of the sample, it is also important to obtain a quantitative estimation of its composition. In order to meet this demand, a new approach based on X-ray Fluorescence coupled to Monte Carlo simulations is proposed. It allows one to distinguish easily between the three manufacturing techniques and to quantify the composition of the sample without any destructive sampling. It constitutes a new tool for the study of complex alloy structures. The protocol is applied here to some ancient Tumbaga gold samples and is described in detail, comparing the results to those obtained with other techniques.

Nuragic Working Tools Characterization with Corrosion Layer Determinations.

From the availability of metals to the technology and tools needed to transform them, roughly every civilization in the Mediterranean basin has a metalsmith story. Many of the objects produced by them share a few peculiar characteristics, usages, or even shapes. In this scenario, a class of objects that can be clustered by their usage, i.e., working tools, stands out from the crowd. For this study, a set of working tools from the Nuragic civilization (Sardinia, Italy) was researched with a non-destructive technique: X-ray Fluorescence (XRF). A quantification of the chemical species present in their alloy was obtained with the use of Monte Carlo simulations. The XRMC package, used for the simulations, managed for the first time to reproduce very complex corrosion layers and to thoroughly characterize them from a chemical perspective. The obtained results were discussed and compared to other results reported in the literature.

The Strange Case of the Nuragic Offerers Bronze Statuettes: A Multi-Analytical Study.

The Nuragic civilization (Sardinia, Italy, XVIII-VIII B.C) developed a flourishing bronze metallurgy with strong connections with other civilizations from the Mediterranean basin. Within the large bronze production, there are some peculiar representations of human figures, known in the archaeological environment of Sardinia as bronzetti, depicting warriors, priests, and offerers. In this paper, an interesting couple of Nuragic statuettes representing offerers, one from the Pigorini Museum in Rome and another from the Musei Reali in Turin, were analyzed. They have been investigated with X-ray fluorescence integrated with Monte Carlo simulations (XRF-MC). The combined methodology provides more accurate results, ranging from the structural characterization to the identification of the corrosion layers to the estimation of the composition of the alloy of the artifact. One of the most striking results regards the heads of the offerers: both heads are covered with a thick iron-based layer, even though the whole artifacts are made of a copper alloy. To understand the reason behind this peculiar corrosion patina, several hypotheses have been considered, including the possibility that these iron mineralizations are the consequence of an ancient superficial treatment, intending to confer a chromatic effect on the figurine's head.