Isotopes yield clues to centuries-old European coins

Science News : The chemical composition of certain metals in medieval and early modern European coins is helping researchers trace not only where New World silver was mined but also which route it took to Europe. In their paper published online in Geology, Anne-Marie Desaulty and Francis Albarede of the école Normale Supérieure in France discuss their analysis of 15 English coins dated between 1317 and 1640. From the coins’ copper, lead, and silver content, the researchers were able to determine that coins minted before about 1553 were made from metals mined in central Europe or England and those minted immediately after that date had silver from Mexico. However, silver from Bolivia that was mined at about the same time as that from Mexico didn’t show up in English coins until almost a century later. The researchers propose that silver from Mexico was exported eastward and therefore found its way into English currency faster than did Bolivian silver, which was probably shipped westward via China.