Purse of medieval silver coins from royal shipwreck revealed by X-ray microscale Computed Tomography (µCT) scanning

We present the archaeological discovery and microscale X-ray Computed Tomography (µCT) scanning of a silver coin purse lost in a medieval shipwreck while the king who issued many of the coins was aboard. The find demonstrates that shipwrecks are extraordinary repositories of historical information, in this case providing insight into one of the most important and dramatic events of medieval Scandinavia. In the summer of 1495, Gribshunden, the flagship of King Hans, ruler of Denmark and Norway, burned and sank in the Baltic Sea en route to a political summit in Sweden. The identified coins in this purse impart direct evidence of Hans’ establishment of new mints to increase the amount of currency in circulation, and his decision not to recall and debase existing coins. These were essential elements of Hans’ comprehensive strategy for consolidating a Nordic political union and constructing a new nation. The recovered coins are too fragile for mechanical separation, but µCT allowed full or partial identification of 82% of the coins in the concreted purse. Our investigations suggest the purse likely was the personal possession of a high-ranking and trusted person in the king’s entourage. Further, the composition of the purse illuminates politics and monetary policy in medieval northern Europe.