Minerals such as gold and silver contain a chemical fingerprint of where they were born, for instance in the composition of copper and lead that appear along with the more precious metals. Anne-Marie Desaulty and Francis Albarède of the Ecole Normale Supérieure in Lyon, France, analyzed 15 English coins, dated between 1317 and 1640, for variations in their copper, lead and silver.
Lead in all the coins before the reign of Mary I, which began in 1553, showed that the ore was at least 220 million years old, suggesting it came from ancient rocks in either central Europe or England. Lead in later coins showed a much higher contribution of silver younger than 50 million years old — suggesting it came instead from the mines of Mexico.
Story: Alexandra Witze, ScienceNews | Photo: Thomas Breston, ENS Lyon