Speakers
Description
Many mines had been in use over several millennia but most ancient workings have been damaged and jumbled by the more recent extraction phases and have become exceedingly difficult to identify and date. For silver mines, isotopes offer a unique opportunity to resolve this conundrum. Over 95% of the 109Ag/107Ag ratios measured in silver coins from different origins, such as Ancient Greece and Iberia, Spanish Americas, medieval and pre-modern Europe, fall in a narrow ±0.1 per mill range, whereas the range for potential ores is more than an order of magnitude broader. Galena ores with high Ag, Sb, and As contents and 109Ag/107Ag ratios in the coinage range represent acceptable sources of bullion and, with some exceptions, make it safe to disregard other ore districts. This approach provides results consistent with literature records describing mines from Ancient Greece and Iberia.
