Recognizing Renaissance or older bronzes from modern ones

X-ray diffraction analysis of bronze coins dating from the 1st to the 19th century CE, together with several modern bronze samples of known composition, has revealed that the natural aging of the Pb–Sn solid solution within lead inclusions occurs over a period of approximately 350 years. During this time, the tin concentration in the inclusions decreases from about 3 at% (or higher) to roughly 1 at%. This gradual depletion of tin provides a measurable indicator of the age of leaded bronze artifacts. The finding expands the time range for distinguishing modern replicas and forgeries from genuine historical or Renaissance bronzes—extending beyond the dating capabilities of conventional ^210Pb analysis.