Abstract
Roman gold jewellery, which was excavated in Ptuj (Poetovio) and consists of a necklace, earrings and a bracelet with embedded emeralds, is part of the Slovenian archaeological artefacts collections. Crystallographic characteristics, inclusions, luminous phenomena and geological characteristics were determined in order to establish the origin of the emeralds. Chemical composition of the emeralds was determined non-destructively using the methods of proton-induced X-rays and gamma rays (PIXE/PIGE). The results were compared with reference emeralds from Habachtal in Austria and with green beryls from the Ural Mts. Literature data for emeralds from Egypt and modern-day Afghanistan area were used to interpret the results. Specifically, these sites were known for emeralds being mined for jewellery in Roman times. It was assumed that emeralds from archaeological artefacts originated from Habachtal in Austria, given that this site was the nearest to the place where found. But the emeralds from the necklace and earrings in fact came from Egyptian deposits. The origin of emeralds from the bracelet could not have been determined absolutely reliably due to the lack of comparative materials; they may originate from a site in modern-day Afghanistan or from Egypt, but certainly not from the same site as the previously mentioned emeralds in the necklace and earrings.
Highlights
V zbirkah arheolo{kih predmetov na Slovenskem hranimo zlat rimski nakit, ki je bil najden na Ptuju (Poetovio); verižico, uhana in zapestnico, ki imajo okovane smaragde
Owing to the relative proximity of the emerald site at Habachtal in Austria it seemed most likely that they originated from this very upland site. This is why we studies crystallographic, physical and geochemical characteristics of emeralds embedded in archaeological artefacts in Slovenia and compared them with reference emeralds from Habachtal
As the emeralds from the archaeological artefacts have preserved their crystal surfaces, we decided to compare the forms of crystals from Habachtal with those in the archaeological jewellery
Summary
The emeralds were initially observed with naked eye and a 10x magnifying loupe. Crystallographic characteristics, inclusions and colour were determined. The PIXE and PIGE methods are based on the irradiation of samples with high energy ions, which induce the characteristic X-rays and gamma rays in the matter. With the first one we measured the low energy spectrum of elements between silicon and iron, while during the second measurement the proton current was increased to a few nA; at the same time, we measured the high energy X-ray spectrum of elements heavier than iron, and gamma spectra. For this purpose, the X-ray detector was equipped with additional absorber made of 0.1 mm thick aluminium foil. Measuring uncertainties are greater during measurements made on natural beryls, which have tiny mineral impurities on their surface, usually flakes of mica, owing to which higher concentrations of potassium and aluminium were determined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
