All that glitters is not gold. Metal artefacts of the Late Iron age and Roman period from Prague Bubenče and Dejvice in the perspective of XRF analyses.
Abstract
The results of the research of collection items from the Late Late Roman and Roman periods from Prague-Bubenche and Dejvice revealed in most cases standard copper alloys, typical for the given periods or individual chronological phases and given categories of finds. The most common alloy from which the artefacts were made is tin bronze, which occurs up to the period Ø B1. An important task of the study was to answer the question of the distribution of Roman material - brass - beyond the few localities from which brass has been detected so far. In this regard, it was possible to successfully expand the current state of knowledge with data from the housing context. An interesting observation is that brass without significant admixtures of other elements such as tin and lead was detected without much doubt in only four objects. At the same time, zinc was clearly detected in the alloys in another fifteen items. However, these conclusions must be taken as approximate, since the chosen method (RFA) tends to indicate inaccurately, or the real values of the metal core and alloy overall may differ. One can, for example, reasonably assume that the high representation of tin brass could in some cases, after the application of other analytical procedures, decrease in favor of brass without significant tin admixtures.
Interesting questions arise from the point of view of comparing material and typological classifications of objects. In the case of skeleton graves II and III, from a typological point of view, different objects have a very similar material composition. In addition, pewter brass with low zinc contents is a rather less common material for its time, and in the environment of rich graves, to which it is usually arranged, we would expect high-quality brass, which was used in the period for the production of a number of similar objects, or to the production of brass mints of the early Roman Empire. Thus, there is an incentive for further research, following the question of the production of a series of jewelry for the purpose of equipping an individual (or the deceased) in one workshop or even in one moment. However, it will be possible to answer these questions only after the involvement of more accurate analytical methods.
From the point of view of the study of small fragments of copper alloys and semi-finished products, several important findings emerge. In the first case, it is the evidence of brass in a semi-finished buckle from the early Roman period, which adds to our knowledge of the early processing of this important material beyond the borders of the Roman Empire, in addition to the context of a settlement with varied production documents. The handling of the brass is probably also indicated by the clipped catcher of the buckle with eyelets, which was probably supposed to enter the recycling chain. In addition, bronze was also processed in the Bubenec agglomeration around the same period. Small fragments of plates and metal rods indicate the recycling (?) of tin bronze in the Ø B1 period. In the Ř C1 period, a contemporary trend in the form of heterogeneous alloys of copper with lead, tin and zinc manifested itself in this category.
The localization of indicators for work with non-ferrous metals - including brass - in the residential agglomeration in the area of Prague-Bubenče and Dejvice with a number of other indicators of non-agricultural production, long-distance contacts and the presence of the elite is probably not only due to the reasonably good state of research in the area. In a broader comparison of findings, on the other hand, he follows the trend of linking work with non-ferrous metals to similar important and extensive housing estates. In the future, it will be appropriate to compare the findings with other locations and, above all, to verify the composition of the alloys with more accurate analytical procedures (SEM-EDS, NAA, ICP-MS). In the case of semi-finished buckles, ingots and other indicators of the processing of non-ferrous metals, there is also the possibility of applying procedures to determine the provenance of copper, or other components of the alloy. Particularly important for further research will be the success of establishing the provenance of tin bronze from the early Roman period, or and other used alloys. If it were proven that the metal in question came from deposits in the territory of the Roman Empire, it would significantly increase the probability that, at least in certain phases of the Roman period, Germanic society was heavily dependent on the import of materials for the production of jewelry and other elements of personal equipment from the territory of the Roman Empire. as was the case with brass. The consequences of such a finding are considerable for a whole range of aspects of the study of the settlement structure, the economy, but also Roman-Germanic relations. From the point of view of comparing the required effort and potential results, this topic appears to be a viable one for the future.