image/svg+xml45XII/1/2021InterdIscIplInarIa archaeologIcanatural scIences In archaeologyhomepage: http://www.iansa.euPossibilities and Limitations of Non-Invasive Analytical Methods in the Examination of Garnet- and Niello-Inlaid Precious Metal Objects – Case Study of Three Polychrome Animal-Style Silver Buckles from the 5th-Century Carpathian BasinViktória Mozgai1*, Eszter Horváth2, Bernadett Bajnóczi11Institute for Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network (ELKH), Budaörsi út 45, 1112 Budapest, Hungary2Department of Archaeometry and Archaeological Methodology, Institute of Archaeological Sciences, Eötvös Loránd University, Múzeum körút 4/B, 1088 Budapest, Hungary1. IntroductionThe use of non-destructive and non-invasive analytical methods is widespread in the archaeometric study of metal objects, particularly in the case of precious metal artefacts, from which sampling is not allowed (or only in a very limited way) due to their high value. However, beside the advantage of their non-destructive nature, each analytical method has its own limitations as well, which have to be taken into consideration during data evaluation and interpretation (e.g., precision, accuracy, surface morphology, surface alterations, and object size). The advantages and limitations of non-destructive analytical methods are presented in this paper in connection with the detailed archaeometric study of three cast, silver, rhomboid belt buckles from the second half of the 5thcentury AD (Figure 1).This study aims to determine the elemental composition of the metal alloy and characterise the decoration techniques (gilding, niello and garnet inlays). The diferent character of these four components set diferent opportunities and limitations to the investigation. The analysis of metal alloy has signifcance primarily in the reconstruction of the organisational background of the production; i.e., in revealing the sort of preceding use and application phases, which attests the economic value of the given raw materials in the period, and on the other Volume XII ● Issue 1/2021 ● Pages 45–67*Corresponding author. E-mail: mozgai.viktoria@csfk.orgARtICLE INfoArticle history:Received: 9thSeptember 2020Accepted: 12thApril 2021DOI: http://dx.doi.org/10.24916/iansa.2021.1.4Key words:polychrome precious metal objectCarpathian Basingarnet provenancegildinghXRFSEM-EDXµ-XRDABStRACtThe use of non-destructive and non-invasive analytical methods is widespread in the archaeometric study of metal objects, particularly in the case of precious metal artefacts, from which sampling is not, or in a limited way, allowed due to their high value. In this study, we highlight the main advantages and limitations of non-destructive analytical methods used on three polychrome animal-style silver buckles from the mid-to-late-5th-century Carpathian Basin. Optical microscopic observations, handheld XRF, SEM-EDX and µ-XRD analyses were performed to determine the chemical composition of the metals and their decoration (gilding, garnet and niello inlays), as well as the microtexture and mineralogical composition of the niello, in order to gain a better understanding of the materials used and reconstruct the manufacturing techniques in detail. The buckles were manufactured from relatively high-quality silver derived from the re-use of gilded silver scrap metal and intentionally alloyed with brass or leaded brass. The presence of mercury indicated the use of fre gilding. The niello inlays are composed of mixed silver-copper sulphides, even reaching the composition of pure copper sulphide; this is the frst time, when copper sulphide niello is observed on a silver object. The almandine garnets most probably originate from Southern India and Sri Lanka.
image/svg+xmlIANSA 2021 ● XII/1 ● 45–67Viktória Mozgai, Eszter Horváth, Bernadett Bajnóczi: Possibilities and Limitations of Non-Invasive Analytical Methods in the Examination of Garnet- and Niello-Inlaid Precious Metal Objects – Case Study of Three Polychrome Animal-Style Silver Buckles from the 5th-Century Carpathian Basin46hand, in assessing the presence of any alloying practice and standardisation.From the middle of the 5thcentury AD, silver became a more important raw material than gold. The combination of these two precious metals provided a new opportunity to enhance the polychrome efect. The use of uncoated gold material or gold plates on silver objects, typical for the Hunnic Period, was superseded by the use of (fre)gilding (Horváth et al., 2019; Mozgai et al., 2019b).In the case of niello, a black silver and/or copper sulphide inlaying material, its artifcial, recipe-like character is the key to identify the process of its making and fusing. Dissimilarities in the composition and technology may refect diferent goldsmithing traditions or even workshop practices. Since the discussed buckles have close relations with late Roman military equipment in several aspects (Böhme, 1974), determination of the mineralogical composition and microtexture of niello inlays may provide relevant new results. Analytical data are expected to prove or disprove the continuity of the late Roman niello recipes and technology.In contrast with the silver alloy and niello inlay, the garnet inlays represent a primary raw material of natural origin. During data evaluation, no chemical transformation/alteration or human intervention needs to be considered. Therefore, in the case of garnet, we could target the localisation of potential geological sources or the identifcation of their character (e.g., alluvial or mined garnet). The proportions of major, minor and trace elements, as well as the combination of special inclusions, have proved to be the fngerprint evidence for (certain/particular) garnet Figure 1. The analysed polychrome animal-style rhomboid silver buckles. A: the buckle from Zsibót-Domolospuszta (buckle ZsD) (Janus Pannonius Museum, Pécs); B: the buckle from Bácsordas (Karavukovo) (buckle B/K) (Hungarian National Museum, Budapest); C: the buckle with an unknown provenance (buckle UP) (Hungarian National Museum, Budapest). The tongues associated with the buckle with unknown provenance (buckle UP). D: tongue decorated with a bird’s head; E: tongue decorated with a bird and boar head (photos: E. Horváth).