Urartian Bronze Helmets

ABSTRACTSThis note presents some new analyses for 13 early copper and bronze artefacts from Turkey in the Collection of the Ashmolean Museum, Oxford. They were not included in a small programme of early copper and bronze objects from Iraq, Syria and Palestine (Moorey and Schweizer 1972, Archaeometry14 (2), 177–198) and conclude this pilot‐project.

Ancient bronze is subject to complex degradation which can lead, in cases where copper chlorides are present, to a cyclic and self-sustaining degradation process commonly referred to as “bronze disease”. If left untreated, bronze disease can eat away at a bronze object until it is entirely deteriorated. The presence of copper trihydroxychlorides is indicative that this process is underway and therefore the detection of these corrosion products is necessary in guiding conservation of ancient bronze artefacts. In this paper we present a high spatial/spectral resolution short wave infrared (SWIR) imaging solution for mapping copper trihydroxychlorides in ancient bronze, combining hyperspectral imaging with an in-house developed unsupervised machine learning algorithm for automated spectral clustering. For this work, verification was obtained through use of an in-house developed reference database of typical ancient bronze corrosion products from several archaeological sites, and from collections of the National Museum of China. This paper also explores the suitability, and limitations, of a visible to near-infrared (VNIR) hyperspectral imaging system as a more accessible solution for mapping copper trihydroxychlorides associated with bronze disease. We suggest that our hyperspectral imaging solution can provide a non-invasive, rapid, and high resolution material mapping within and across bronze objects, particularly beneficial for analysing large collections in a museum setting.

In the Saharna microregion (Rezina district, Republic of Moldova), four settlements and one burial attributed to the Holercani-Hansca culture are currently known. In the settlements Saharna Mare / “Dealul Mănăstirii” and Saharna “Rude”, a bronze hairpin of Ösennadel type and a crescent pendant with vertically perforated shank were recently discovered. Both objects have many analogies in Transylvania as well as in Central Europe, being dated within the period Bz D – Ha A1. Along with the finds from Saharna microregion, in the area of the Holercani-Hansca culture, in the sites of Calfa, Holercani, Coșnița and others, other bronze artifacts are known, also of Western origin and having the same chronological markers. Thus, the presence of these objects denotes the connections of the communities from the Prut-Dniester area with Transylvania and Central Europe.

Open image in new window The observed lead isotope ratio and chemical composition of the bronze objects in the Phum Snay site suggest that more than 90% of the bronze materials originated from southern China and the remaining materials were transported from Thailand. India was not the source for the bronze materials. Notable changes in bronze materials were evident throughout the different phases of Phum Snay ­burials. These changes were not only indicated by the variety of chemical compositions but also by the change of provenance in southern China of the copper or bronze materials.

Neutron Imaging of Archaeological Bronzes at the Oak Ridge National Laboratory