AВТЕНТИЧНІСТЬ НУМІЗМАТИЧНИХ ПАМ’ЯТОК ЗІ СРІБЛА НА ПРИКЛАДІ ГРИВНІ ДАВНЬОЇ РУСІ
AUTHENTICITY OF NUMISMATIC MONUMENTS MADE OF SILVER USING THE EXAMPLE OF THE HRYVNIA OF ANCIENT RUS

Summary/Abstract: To confirm the authenticity of numismatic monuments made of silver, it is important to study the internal structural and material changes that occur in metals over a long period of time. The results of the study also provide a basis for the justified removal from the antique market of numerous fakes, as well as souvenir copies, which are often passed off as authentic historical monuments. These studies are especially important for the formation of numismatic collections and a thorough scientific study of unique ancient coins. The purpose of the article is to describe the most characteristic structural and chemical features of silver objects with a long history of existence, using the example of a silver hryvnia of Ancient Rus from a private collection, which can be considered rare due to the presence of a 12th-century graphemes on it. Research methods. The surface of the silver hryvnia of Ancient Rus was studied using an optical microscope with a digital camera. Also, in order to more deeply study the structural and material consequences of the process of natural recrystallization of the metal, the artifact presented for examination was studied using an electron microscope, which has the ability to conduct chemical analysis of micro-areas with dimensions of 2-5 nanometers. Main results of the study. The surface relief of the silver hryvnia, as well as the relief of the areas on which the inscriptions in Church Slavonic are located, has the same traces of the long-term influence of external factors - dissolution, corrosion and natural recrystallization of the metal. Numerous decompression cavities are observed on the surface, formed not only as a result of the appearance of gas bubbles in the melt, but also as a result of the dissolution of numerous foreign mineral impurities mechanically introduced into the melt. The cavities in the hryvnia have areas with the primary “nodular structure” of the surface, which is indicative of the internal aggregate structure of mineral aggregates on the surface and, at the same time, indicates the recrystallization of silver, and is also inherent in ancient artifacts made of this metal. An image of the surface of a silver hryvnia in electronic light is presented in the area where two scratches are observed - ancient and modern. The scratch, which is part of the ancient inscription, is smoother with signs of corrosive dissolution of the surface, covered with mineral aggregates; has a significant level of surface oxidation, and its edge is devoid of edge material and visible defects associated with mechanical impact. The inscriptions present on the hryvnia do not show signs inherent in modern scratches: increased chemical differentiation and the presence of traces of used tools. The surface of the metal within these inscriptions completely repeats the signs observed on the entire surface of the metal. The results of an analytical study of the chemical composition of the surface of a silver hryvnia are presented. The surface of silver is covered with mineral crusts – compounds of chemical elements (Cu, Fe, Al and Si), which were eliminated from the alloy during its natural recrystallization and formed as a result of interaction with the environment. The process occurred throughout the history of the hryvnia. A platinum-enriched area was found, which has a reaction boundary at the contact with the silver alloy – the result of chemical interaction with the silver alloy. This indicates the nature of this inclusion – a fragment brought from ores to the silver alloy mechanically. At the same time, the presence of chlorine, which is observed in the results of the study very often, is due to changes in the composition of the surface due to the later action of chemical factors on it, in particular, detergents. The chemical composition of the surface of the silver hryvnia is characterized by a high level of heterogeneity, which is inherent only to ancient artifacts, where the phenomena of recrystallization and phase differentiation are most clearly observed. The chemical composition of the eliminated chemical elements and the ratio of their concentrations correspond to the chemical composition and ratio established on well-verified silver artifacts. Conclusion. The research has shown that the silver hryvnia of Ancient Rus submitted for examination, as well as the inscriptions on it, are authentic and represent valuable artifacts of ancient history. The signs revealed during detailed research should be considered criteria for substantiating conclusions about the authenticity of silver objects with a long history of existence.

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