Analytische Untersuchungen zu ostgeorgischen Bronzeobjekten: Das Fallbeispiel Nazarlebi

Abstract

The Late Bronze Age and Early Iron Age in the South Caucasus is characterised by an exceptional wealth of metal objects, which is particularly pronounced in East Georgia. In 2018 and 2019, three deposit finds representative of this metal wealth were excavated here in the sanctuary of Nazarlebi (Prov Kakheti). Depot 1 contained 484 bronzes, 457 of which were mock swords, i. e., metal sheets in the shape of a broad sword blade but with hilt frames and wooden inlays still inside. The remaining objects are further weapons or tools. The other two deposit finds 2 and 3 included more than 360 jewellery objects and various chains with pendants, which are also interpreted as rattles.

From this abundance of objects, 67 artefacts were selected to conduct a regional study on metal use and processing. A total of 82 samples were taken from 14 lance points, 15 mock swords and various jewelery elements as well as chain links and pendants in order to carry out material classifications and lead isotopies as well as metallographic analyses on microsections. This was the first time that finds from a stratified and well-dated site in East Georgia could be examined in more detail, in order to record differences in material composition and to demonstrate their raw material origin.

The investigations prove that within the object groups of the Nazarlebi deposits there is predominantly a uniformity in the composition of the metal, but striking optical differences can be recognised, for example, between weapons and jewellery elements. This speaks for purpose-bound alloys, i. e. the metal craftsmen followed a fixed concept in the composition of the alloys for certain forms.

For the production of jewellery such as rings, for example, tin was predominantly alloyed into the molten copper, which on the one hand improved the casting capability and the degree of hardness, and on the other hand influenced a change in the colour of the reddish copper towards a golden shimmer. A different procedure was used in the production of chain links, which suggest only a small addition of arsenic to natural arsenic copper to produce a more silvery sheen.

Furthermore, there is evidence of the addition of antimony in larger quantities in a few objects. The investigation result of a (mace-head) bead with only a thin metal coating over a mineral core could indicate a sparing use of antimony bronze.

Traces of mechanical reworking can be seen on many artefacts as well as on all jewellery or rattle items. It is obvious that the mock swords are completely unsuitable for use, but they have been given an organic grip and some of the blade-shaped metal sheets have also been reworked; on a few pieces that have been restored so far, hallmark decoration has been uncovered.

In terms of their material composition, the lance points could have been used for fighting or hunting. However, the metallographic examination showed that due to a lack of reworking of the blades after casting, they were unusable.

Overall, the investigations on the objects from Nazarlebi show that recycled copper did not play a role and that the raw material sources of copper are to be sought regionally. Much points to deposits in the eastern Great Caucasus, which were prospected a few years ago. The area of origin of the copper could thus be clearly narrowed down, providing important insights not only into the distribution but also into the production of the pieces.