Roman mining archaeology

Rome’s presence in the territory that would become Portugal cannot be measured solely in cities, roads and temples: it is also measured in metal. The province of Lusitania and the Galician North-West were, for the Empire, above all a vast mining district. From there came the gold that fed the imperial treasury and the copper that sustained the monetary and military economy — and Roman mining archaeology is today the discipline that reconstructs that industry from the scars left on the landscape.

The gold of the North: Tresminas

High in the Serra da Padrela, in Vila Pouca de Aguiar (district of Vila Real), the Roman mining complex of Tresminas is the most spectacular testimony to Roman gold mining in Portugal. The exploitation may have begun under Augustus and continued until the end of the second century, reaching its peak in the first and second centuries AD. The gold was torn out in open pits, in enormous cortas — gigantic trenches carved into the granite, of which the Corta da Ribeirinha and the Corta de Covas still impress by their scale today — and also in underground galleries, linked by shafts and threaded by kilometres of tunnels.

The operation depended on water: long channels brought it from distant springs to wash the crushed ore and separate the particles of gold. It was a state-run operation, whose product was destined exclusively for the imperial administration. Close to Tresminas, the lodes of Gralheira and Jales completed one of the largest gold- and silver-bearing complexes of Roman Europe.

The copper of the South: Vipasca

In the Alentejo, on the Iberian Pyrite Belt, present-day Aljustrel corresponded to the Roman settlement of Vipasca. Here it was not gold that was sought but copper — and, in smaller quantities, silver. The volume of slag left by the smelting, estimated at more than one hundred thousand cubic metres, gives the measure of an almost industrial operation, active above all in the first and second centuries AD.

What makes Vipasca (Aljustrel) exceptional is, however, not its scale but its law. In 1876 and 1906, two bronze plaques bearing inscriptions in Latin were recovered from the mine dumps — the Vipasca Tablets. The second, the Lex Metalli Vipascensis, datable to the reign of Hadrian (117–138 AD), regulated the life of the mining district in detail: the granting of shafts, the deadlines for beginning exploitation, the collection of taxes, but also the running of the baths, the barber, the cobbler and the school.

The Vipasca Tablets are, perhaps, the document that best shows how Rome turned a mine into a regulated social organism — not merely a hole in the ground, but a community with laws of its own.

Organising mining labour

These two poles reveal two models of exploitation. Tresminas represents the great state mine, devoted to a precious metal and managed directly by the imperial administration; Vipasca shows a district where the State leased the concessions to private individuals — the coloni — under a strict legal framework. In both, the workforce combined free workers, contracted labour and, to a large extent, slaves and convicts.

The reconstruction of this world is the task of Roman archaeology in Portugal, which combines the reading of the pits and galleries with the study of the slag, the tools and the epigraphy. Set within the broader history of mining heritage, Roman mining teaches us to read the landscape of the Portuguese interior as the result of an immense and ancient labour, whose marks the vegetation has covered but not erased.