A study by the UAB and the University of A Coruña has succeeded in demonstrating the existence of Roman-era alluvial gold mines in the Eastern Pyrenees. The discovery was made possible by dating two samples from the infill levels of the hydraulic structures at the Guilleteres d'All mines using new luminescence techniques (OSL), yielding a chronology of around the 3rd–4th centuries CE. This calculation fully confirms the Roman origin of the structure and allows confirming for the first time the exploitation of Pyrenean gold by the Romans in this region.
The presence of gold in the alluvial deposits of the Segre River, as in other rivers originating in the Pyrenees, is a well-known phenomenon: it is secondary gold, originating from the Miocene deposits of the axial Pyrenees, which the waters of the Segre and its tributaries deposit along the river's course onto its terraces, from the Cerdanya to the Lleida plain.
Islamic sources already spoke of it, when referring to the gold of the Segre and its good quality for minting coins. However, literary and archaeological evidence from some years ago allowed researchers to propose the existence of alluvial gold mines in the Cerdanya in Roman times. These studies located a workshop where gold was worked; silver and cinnabar at the Castellot de Bolvir site (2nd-1st centuries BCE); as well as a large complex of erosional structures in the Cerdanya Miocene deposits, possibly the result of mining activities using the hydraulic technologies developed by the Romans (Guilleteres d'All site).
The Roman technique for extracting alluvial gold was based on eroding the gold-bearing deposits with water. They used various washing methods that ranged from simply channeling water through the sediments to constructing galleries and flooding them with pressurised water.
A study coordinated by professors Oriol Olesti Vila, of the Department of Ancient and Medieval Studies at the UAB, and Jorge Sanjurjo, of the University Institute of Geology at the University of A Coruña, focused on the excavation of a large hydraulic deposit that was part of the exploitation system, but which, due to the scarcity of archaeological materials, was difficult to date. To this end, in 2022 a dating strategy using Optically Stimulated Luminescence (OSL) was initiated on the infill levels of the hydraulic structure. This technique allows for the dating of detrital sedimentary materials and of quartz in particular, since when buried in an archaeological layer, they begin to receive a flow of radioactive particles that can be measured and dated. This dating method is not as precise as C-14, but it has the advantage of not requiring organic matter, which is nonexistent at the Guilleteres d'All.
Researchers dated two samples from the same structure using OSL, which, although providing a wide chronological range, fully coincided with the 1st–4th centuries CE, a time when the mine was undoubtedly already abandoned and its depletion process had begun. This chronology fully confirms the Roman origin of the structure and, for the first time, allows researchers to confirm the exploitation of Pyrenean gold by the Romans in this region.
It is not surprising that, in this regard, the alluvial gold mines are located some 10 km from the Roman city of Iulia Livica (present-day Llívia), the only one documented in the Pyrenees and therefore likely a centre that played an important role in the organisation and exploitation of this resource.
Reference:
Sanjurjo-Sánchez, J., Morera Camprubí, J., & Vila, O. O. (2025). First Evidence of Roman Gold Mining Obtained by Luminescence Dating of Sediments in Les Guilleteres D'All (Cerdanya, Girona, Eastern Pyrenees). Land, 14(9), 1912. https://doi.org/10.3390/land14091912
