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The Hoard of Beçin

Medieval excavation site of Beçin Kalesi in Turkey.

In summer 2000 about 60000 coins were excavated by a team of archaeologists of the University of Izmir (Head: Prof. Rahmi Ünal) at the medieval site of Beçin Kalesi in Turkey. The coins of interest stem from the Ottoman Empire and were produced during the 16th and 17th centuries under the Sultans Murad III, Mehmed III and Ahmed I in 18 different mints. This finding is one of the most important numismatic discoveries in Turkey – it is the largest hoard ever found in total numbers and the most important Ottoman treasure ever discovered.

In a co-operation between the Turkish and the Austrian Academies of Sciences a project has been carried out in order to collect chemical, numismatic, archaeological, historical and economical commentaries and prepare a catalogue of these coins.

The coin hoard suffered from a fire, which melted the coins forming a clot, and most of the coins showed a green patina on their surfaces due to corrosion in the soil. The phenomena of corrosion and surface enrichment of precious metal alloys can give an erroneous impression of the bulk composition of the coin, so it was agreed to take small samples of approximately 450 objects typical for the period as well as the mints.

Medieval excavation site of Beçin Kalesi in Turkey.  
   
The aim of the scientific work was to determine their genuine fineness and to trace back to the ore deposits/mines supplying the metals used for manufacturing these coins. Therefore, the cross-sections of the coins were analysed by micro x-ray fluorescence analysis (µ-XRF), scanning electron microscopy with energy dispersive x-ray spectrometry (SEM/EDX), proton induced X-ray emission spectroscopy (PIXE) and synchrotron micro X-ray fluorescence analysis (SR-XRF).

Economic historians agree that from the 1580s until the 1640s the Ottoman Empire has gone through monetary instability arising from fiscal, economic and political difficulties, which led to the occurrence of frequent debasements. The silver content of the coins should have been reduced by 44%.

However, in contrast to these interpretations, the analyses have shown that the average silver content of the coins of all 3 Sultans is about 95%.

Coin belonging to the Ottoman Empire.
  Coin belonging to the Ottoman Empire.

Poster

Papers:

M. Rodrigues, M. Schreiner, M. Mäder, M. Melcher, M. Guerra, J.  Salomon, M. Radtke, M. Alram, N. Schindel:
The Hoard of Beçin -  non-destructive analysis of the silver coins.
Applied Physics A:  Materials Science & Processing, Special Issue: “Synchrotron Radiation  Applied to Art and Archaeology” 99 (2010) 351-356

M. Rodrigues, M. Schreiner, M. Melcher, M. Guerra, J. Salomon, M.  Radtke, M. Alram, N. Schindel:
Characterization of the silver coins of  the Hoard of Beçin by X-ray based methods, Nuclear Instruments and  Methods
Physics Research Section B: Beam Interactions with Materials  and Atoms, Special Issue dedicated to the ECAART 2010 (Article in Press)