Treasures of chopped silver

Treasures of chopped silver in the Oder-Neisse region: archaeological-analytical investigations into the origin of silver in early medieval East Central Europe

The phenomenon of fragmentation of coins, jewellery and costume accessories made of silver – so-called chopped silver – is evidence of a weight money economy common in eastern and northern Europe from the 9th to the 11th century. The trade value is not based on the nominal value of the coin or the craftsmanship quality of the piece of jewellery, but is limited solely to the material value of the silver contained in the coin or jewellery.

Participants: Dr. Jasper Freiherr von Richthofen, PD Dr. Felix Biermann

The project funded by the Volkswagen Foundation (“Research in Museums” programme) therefore aims to clarify the origin of the treasure components and the manufacturing material by archaeological-typological and scientific investigations of selected finds. The investigation will focus on fragmented jewellery and costume components. Finds from various museums are used for this purpose. The area of work is the Oder-Neisse region, one of the central communication and transfer areas of Eastern Central Europe in early historical times. A total of 20 treasure finds from East Germany are being examined. The methods used for the first time in this combination allow important cultural and economic historical findings to be made. At the same time, the treasure finds are an impressive and equally enigmatic part of the project’s collection of German and Polish archaeological museums, the research, publication and presentation of which will undoubtedly attract considerable public attention.

Report

The scientific analyses of about 400 selected finds aim to determine the chemical composition and the isotope ratios of the lead of the silver finds. These data serve on the one hand to classify the material, which is compared to the archaeological one, and on the other hand to determine the origin of the raw materials, but not only the origin of the raw silver used for coinage or jewellery production is of cultural and historical interest and allows insights into the distribution of silver or the origin of the finished products.

In connection with the chemical analysis of silver, the lead isotope ratios can, for example, provide important information on the coherence of different fragments of a single object within a treasure find and on the classification of materials in general, which can be compared and, if necessary, linked to the archaeological-typological classification. For example, the distribution of certain groups of materials or alloys in space and time or their recurring evidence on specific types of objects, e.g. certain coinage or forms of traditional jewellery, can lead to the identification of production centres or point to common provenances.

During sampling in museums, non-destructive material analyses can be carried out with a portable X-ray fluorescence spectrometer. These give at least an overview of the alloys used, but are not representative for the whole object, especially in the case of corroded objects. For this reason, a small (approx. 10 mg) material sample is usually taken from each object, which is cleaned in the laboratory and quantitatively analysed by means of X-ray fluorescence and/or mass spectrometry coupled with laser ablation with regard to the main and trace elements. In such projects, the question of a specific manufacturing technique often arises, e.g. for gilding. In this case, the sample can be examined with a scanning electron microscope before further processing to determine, for example, the thickness and application technique of the gold layer.