The mines at Rio de Frades, an important geosite with high mining value from Arouca Geopark, were brought into operation in 1914 and belonged to the Mining Company of Northern Portugal, property of Germans. The wolfram or “black gold” was the ore explored here, used for weapons manufacturing during the first two world wars. Valued at 150 escudos per kilo in the market but came to be transacted at 1000 escudos/kilo at smuggling prices (a small fortune at the height of the war). 3000 people worked here, and in the vicinity of Rio de Frades were opened ore than 6 km of galleries for exploration of the veins. In more numbers were those who, on their own, explored the valuable ore – the “pilhas” (looters) – and thereby won good money overnight risking, however, their lives.
Rio de Frades is a place of exceptional biodiversity, with the shale torn deep valleys being refuge for species such as the iberian wolf. The abandoned galleries are today important refuges for cave bat colonies inhabiting the Gralheira massive.Rocky outcrops are preferred habitat of pedunculated anarrhinum (endemic plant of these mountains) and lipferns (the scaly and the iberian lipfern species), which occur in the crevices of the rocks. On river Frades, a tributary of Paivô, there are unique species like the pyrenean desman and the iberian newt indicator of mountain rivers with clean water.
The Caminho do Carteiro (Postman Way) is much more than a tourist trail marked on the top of the mountain as it provides a privileged view of the numerous ruins of Minas de Rio de Frades. Ending at the crossing of the Vale da Cerdeira gallery, this trail of ruins allows us to understand the era of “black gold fever” and the extraction process of this type of ore. Across the gallery, a magnificent waterfall rewards the bold ones, in an idyllic corner where the interaction of stone and water gave sculptures of rare beauty.