Global situations such as economic recovery after a pandemic, geopolitical instability, and future digital and energy transition are some of the drivers for the European Union (EU) to explore new and existing sources of raw materials. The Iberian Pyrite Belt in the southwest of the Iberian Peninsula (Spain and Portugal) hosts a great number of tailing deposits from centuries of mining operations. A unique tailings deposit has been studied and characterized. The similarities with other tailing deposits deeply studied suggested the presence of critical raw materials. Furthermore, a very gross reserves estimation was made. The characterization and reserves estimations were compared with the bibliography from mining companies who operated in the area decades ago and from the bibliography available at Fundación Riotinto. The presence of critical raw materials was confirmed, some of them in high concentrations. Moreover, a singular difference was found compared with other similar tailings stored within the Iberian Pyrite Belt. The main valuable metals identified were Au (2.25 ppm), Ag (215 ppm), Co (131 ppm) and Cu (0.29%). The reserves estimation showed that this deposit potentially hosts 1.86 t of Au, 177 t of Ag, 108 t of Co or 2358 t of Cu; in other words, with a copper average price of 8366 US$/t in December 2022, the tailings deposit contains a potential value of more than 19 million USD.