Analysis of metals with luster: Roman brass and silver

Fajfar, H.; Rupnik, Zdravko; Šmit, Ž.

doi:10.1016/j.nimb.2015.09.081

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…Indeed, the use of a specific metal or alloy, in addition to a standard weight of coins, was needed in ancient times as today to guarantee the authenticity and the value of each denomination in circulation (Smekalova, 2009). Probably, the first coins in orichalcum were minted in the Kingdom of Pontus and in the regions of Phrygia and Bithynia, during the reign of Mithridates VI (120-96 BC) (Fajfar et al, 2015;Smekalova, 2009). According to the current state of the studies (Amela Valverde, 2004;Catalli, 2003), the Roman coin production in orichalcum is limited to the Caesarean Era and to the phase of the Julio-Claudian dynasty, from the 23 BC reform to 68 AD ca; in particular, the use of brass to strike coins under the reign of Julius Caesar (from the beginning of his dictatorship in 49 BC until his death in 44 BC) can be considered as experimental (Crawford, 1974), as shown in the studies carried out by Amela Valverde (2004) on the emissions C. Clovio, RRC 476 and Q. Oppius, RRC 550, and it was suddenly halted due to Caesar's death in 44 BC.…”

Section: Historical Backgroundmentioning

confidence: 99%

Multi-analytical approach for an archaeometric study on orichalcum coins

Fazio¹

2022

ROL

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Orichalcum is a Cu-Zn based alloy known since the 1 st millennium BC. The cementation was the ancient technique used for its production. The PhD project here presented aimed to characterise this alloy and to evaluate its degradation: for this purpose, non-destructive, nano-invasive and destructive techniques were used on a collection of ancient coins issued from the 1 st century BC to the end of the 1 st century AD. In particular, a multi-analytical approach was used: to investigate the patinas and their corrosive patterns, to study the alloy microstructures and their degradation, to describe the dezincification process and grouping the coins by emission. In addition, quantitative analyses allowed a complete characterization of this ancient alloy. The multi-analytical approach allowed to review the previous theories used for dating samples in orichalcum. This project wanted to contribute to the current knowledge on Roman coinage and to attempt to investigate the mechanisms of corrosive processes affecting ancient alloys.

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Section: Historical Backgroundmentioning

confidence: 99%

Multi-analytical approach for an archaeometric study on orichalcum coins

Fazio¹

2022

ROL

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“…Superficial tension between the copper blank and the amalgam allows for a thin-layer deposit on its surface. Mercury evaporates after extraction from the amalgam, leaving a thin layer of high-purity silver [18,19].…”

Section: Introductionmentioning

confidence: 99%

Ag and Sn Implications in 3-Polker Coins Forgeries Evidenced by Nondestructive Methods

Petean,

Paltinean,

Taut

et al. 2023

Materials

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Several forged 3-Polker coins have been reported in historical sources on the financial crisis that occurred between 1619 and 1623 at the start of the 30-year-long war. Supposedly, belligerent countries forged other countries’ coins which were then used for external payments as a war strategy. Thus, a lot of 3-Polker coins (e.g., Sigismund-III-type) were forged, and the markets became flooded with poor currency. In the present day, these pre-modern forgeries are rare archeological findings. Only five forged 3-Polker coins randomly found in Transylvania were available for the current study. There are deeper implications of silver and tin in the forgery techniques that need to be considered. Thus, the forged 3-Polker coins were investigated via nondestructive methods: SEM microscopy coupled with EDS elemental spectroscopy for complex microstructural characterization and XRD for phase identification. Three distinct types of forgery methods were identified: the amalgam method is the first used for copper blank silvering (1620), and immersion in melted silver (1621) is the second one. Both methods were used to forge coins with proper legends and inscriptions. The third method is the tin plating of copper coins (with corrupted legend and altered design) (1622, 1623, and 1624). The EDS investigation revealed Hg traces inside the compact silver crusts for the first type and the elongated silver crystallites in the immersion direction, which are well-attached to the copper core for the second type. The third forgery type has a rich tin plating with the superficial formation of Cu6Sn5 compound that assures a good resistance of the coating layer. Therefore, this type should have been easily recognized as fake by traders, while the first two types require proper weighing and margin clipping to ensure their quality.

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“…The use of gold, silver (since 400 BC), copper, bronze and brass alloys to manufacture the Roman coins, for instance, is one of the pioneering mass production of metallic artefacts in history. The main minting processes were casting and plastic deformation; the latter could use hot or cold striking [9][10][11] . The metallographic analysis of two types of brass coins used by the Romans (Dupondius and AE) indicate the use of hot striking at temperatures above 800°C, see Figures 2a and 2b 10,11 .…”

Section: Introductionmentioning

confidence: 99%

“…The main minting processes were casting and plastic deformation; the latter could use hot or cold striking [9][10][11] . The metallographic analysis of two types of brass coins used by the Romans (Dupondius and AE) indicate the use of hot striking at temperatures above 800°C, see Figures 2a and 2b 10,11 . According to Calliari et al 12 , the Roman coinage process of Cu-base alloys between 100 and 300 AD could be divided into four steps: the production of alloys and casting; the blank manufacture; the hammering and annealing to produce the coin geometry; and the coin embossing by die striking.…”

Section: Introductionmentioning

confidence: 99%

History of the Recrystallisation of Metals: A Summary of Ideas and Findings until the 1950s

Azevedo

Padilha

2020

Mat. Res.

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The paper reviews the events that led to the understanding of the recrystallisation of metals throughout history, covering the timeline from 3500 BC until the 1950s and dealing mainly with the misconceptions related to the "recrystallisation" and "amorphisation". This history begins with the thermomechanical processing of native metals in pre-Columbian America (3,000 BC), and the production of brass coins in Rome (100 BC). The analysis of the fracture surfaces of metals, commonly used between the 16 th and 18 th centuries in Europe for the quality control of metallic products, is briefly discussed. The observation of crystalline and fibrous fractures lead to the common misconception of the 19 th century that "recrystallisation" takes place during the heating of "amorphous" cold-worked metals. The use of reflecting optical microscopy in the late 19 th century indicated, however, that the plastic deformation only promotes a morphological change in the microstructure of the metals without any "amorphisation". In the early 20 th century, the plastic deformation of metals by crystal plane slipping and twinning was well documented by metallographic observation during tensile testing. Nevertheless, in 1915, Prof. Rosenhain advocated that the "crystal" inside the slip bands of a plastically deformed metal was "amorphous" and responsible for the work hardening. The discovery of the X-ray diffraction technique, in 1913, allowed to resolve the ongoing dispute of the "amorphisation" of metals during plastic deformation. Between the 1920s and 1950s, X-ray diffraction was practically the only means of studying the internal structure of metals to explain the nature of their plasticity, confirming many aspects of the dislocation theory. This technique was crucially important to understand the atomic crystal structure of metals in the annealed and cold-work states. Our history finishes in the 1950s when the transmission electron microscopy finally revealed the first images of dislocation in metals. Up to that date, most of the understanding of the dislocations' distribution and organisation in cold-work and annealed states had already been derived from X-ray diffractograms, which gave birth to the modern physical metallurgy.

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Analysis of metals with luster: Roman brass and silver

Cited by 6 publications

References 14 publications

Multi-analytical approach for an archaeometric study on orichalcum coins

Multi-analytical approach for an archaeometric study on orichalcum coins

Ag and Sn Implications in 3-Polker Coins Forgeries Evidenced by Nondestructive Methods

History of the Recrystallisation of Metals: A Summary of Ideas and Findings until the 1950s

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