First Evidence of Roman Gold Mining Obtained by Luminescence Dating of Sediments in Les Guilleteres D’All (Cerdanya, Girona, Eastern Pyrenees)

In recent years, evidence of gold mining during the Roman period has been found by archaeologists in the Cerdanya region (Girona, Catalonia). In this region, Les Guilleteres d’All has been described as a mining complex because of the erosive features observed in the landscape; surveys have identified hydraulic mining opencast structures named chantier-cirques and chantier-ravins. The latter are smaller, but both require a water reservoir, specifically a water retention facility, to supply water flow. One of these buried water reservoirs has been excavated, revealing an enlarged area with a dam constructed from stone blocks. Two pottery sherds were found within the sediment layers deposited on the bottom of the reservoir—one dated to the 1st–2nd c. AD and the other to the Bronze Age—indicating that the reservoir was filled during historical times and the nearby presence of settlements from these periods. Optically Stimulated Luminescence (OSL) dating was performed on two waterlain sediment layers deposited at the bottom deposited at the reservoir. The obtained ages, dating to 2nd–4th c. AD, correspond to the final phase or abandonment of mining activities. Hence, these ages provide the first evidence of mining activities in Les Guilleteres during Roman times.