Phase Composition and Its Spatial Distribution in Antique Copper Coins: Neutron Tomography and Diffraction Studies

Abstract

The chemical and elementary composition, internal arrangement, and spatial distribution of the components of ancient Greek copper coins were studied using XRF analysis, neutron diffraction and neutron tomography methods. The studied coins are interesting from a historical and cultural point of view, as they are “Charon’s obol’s”. These coins were discovered at the location of an ancient Greek settlement during archaeological excavations on the “Volna-1” necropolis in Krasnodar Region, Russian Federation. It was determined that the coins are mainly made of a bronze alloy, a tin content that falls in the range of 1.1(2)–7.9(3) wt.%. All coins are highly degraded; corrosion and patina areas occupy volumes from ~27 % to ~62 % of the original coin volumes. The neutron tomography method not only provided 3D data of the spatial distribution of the bronze alloy and the patina with corrosion contamination inside coin volumes, but also restored the minting pattern of several studied coins. Taking into account the obtained results, the origin and use of these coins in the light of historical and economic processes of the Bosporan Kingdom are discussed.

Microtomographic Analysis of a Palaeolithic Wooden Point from the Ljubljanica River

“…No article was dedicated to the problem of direct reconstruction of 3D models from 2D tomography images. The 3D models were reconstructed using commercial industrial tomography software (VGStudio MAX [ 31 , 34 , 35 , 37 ], Amira Avizo 9.0 [ 32 , 33 ], Simpleware—Synopsys, Inc, Dragonfly Pro—Carl Zeiss) and in most cases analysed from 2D slices in different layers. In no case did we record the use of any of the open source programmes to represent a 3D anatomical model.…”

“…Current research interests in the noninvasive use, reconstruction, visualisation and processing of 2D µCT images include: analysis of all types of materials [ 32 ], analysis of the condition and production method of ancient Egyptian statues for restoration [ 31 ], morphological odontometric analysis of dental artefacts [ 33 ], visualisation of alloy composition and corrosion exposure of ancient Greek coins [ 34 ], evaluation of the suitability of µCT for the study of ceramic manufacturing technology [ 35 ], visualisation of the condition of clothing fabrics [ 36 ], analysis of manufacturing techniques and porosity levels of model samples of selected building materials (mortar) in historical objects [ 37 ], determination of the condition of the artefact before restoration [ 38 ], etc. An interesting example is the development of a system for the simultaneous use of computed tomography and photogrammetry [ 39 ] hardware for the visualisation of a 3D model.…”

Non-destructive structural studies of coins from the Uzundara Fortress using X-ray diffraction and neutron tomography

“…Currently, active experimental research is being conducted on the coins discovered during excavations using both traditional research methods and modern methods of non-destructive structural diagnostics [9][10][11][12][13]. Such structural methods include the X-ray diffraction method [14,15], which makes it possible to obtain information about the phase composition of the investigated object, and the neutron imaging methods, which allows to obtain the spatial distribution of phase components in the volume of the studied coins [13,14,[16][17][18].…”

“…Currently, active experimental research is being conducted on the coins discovered during excavations using both traditional research methods and modern methods of non-destructive structural diagnostics [9][10][11][12][13]. Such structural methods include the X-ray diffraction method [14,15], which makes it possible to obtain information about the phase composition of the investigated object, and the neutron imaging methods, which allows to obtain the spatial distribution of phase components in the volume of the studied coins [13,14,[16][17][18]. The neutron tomography method, due to the features of the neutron beam interaction while passing through the elements of the investigated object with different chemical compositions, thickness and density, makes it possible to obtain detailed information about the internal structure of metal coins [16,19] with a spatial resolution at the micron level [20], as well as to obtain a virtual three-dimensional model of the coin for further analysis.…”

“…The neutron tomography method, due to the features of the neutron beam interaction while passing through the elements of the investigated object with different chemical compositions, thickness and density, makes it possible to obtain detailed information about the internal structure of metal coins [16,19] with a spatial resolution at the micron level [20], as well as to obtain a virtual three-dimensional model of the coin for further analysis. The complex of the above-mentioned experimental methods of structural diagnostics makes it possible to reveal internal defects or cracks, identify the corrosion spread, and investigate the phase composition in copper [13] and silver [21,22] numismatic objects.…”