Tharsis-La Zarza mining basin
[4] The Tharsis-La Zarza mining basin is located in the east of the province of Huelva, within the limits of the Andévalo region, extending to the estuaries of the Odiel and Tinto rivers.
In contemporary times, the main mining centers of the basin were "Tharsis" and "La Zarza", both located within the municipalities of Alosno and Calañas, respectively.
In the settlement of Cabezo Juré, located in the municipality of Alosno, excavations in contemporary times have recorded the existence of prehistoric copper smelters.
[10] The metallurgical production of this period reached its peak during the 6th and 5th centuries BC, under the influence of the Iberian Peninsula's trade with the eastern Mediterranean territories.
[13] The Tharsis deposits were probably active at least until the general crisis of the Lower Empire (3rd-4th centuries), and their exploitation was definitively abandoned around the beginning of the Visigothic period.
[14] The mining work undertaken in this area during Antiquity was of such a magnitude that it left an important mass of slag heaps and considerably altered the physiognomy of the territory.
It is a fact that the vast majority of mining operations in the Iberian Pyrite Belt remained inactive since the end of the Roman period.
It was during the 19th century when the deposits of the Alosno mountains were visited again by mining engineers such as Fausto Elhuyar, Joaquín Ezquerra, Agustín Martínez Alcíbar or Luciano Escobar.
[16] At the same time, foreign capital also began to show interest in the deposits of the western Andévalo, especially in view of the difficulties encountered in acquiring the Riotinto mines from the State.
[17] The activity of the mining basin would be reactivated by the French engineer Ernest Deligny, who showed interest in the area after a visit to the Alosno mountains and the Huelva estuary in February 1853.
[20] The Gallic company managed to exploit the deposits, having in the British industrialists the main client for the mining production of pyrites, sulfur, etc.
As a result, in 1866 the French leased the exploitation of the mines to the British Tharsis Sulphur and Copper Company Limited by means of an amicable agreement.
Shortly after starting its activities in Spain, the British company also undertook the construction of a railway line,[22] as well as a pier-dock on the Odiel River to dispose of the extracted minerals.
[24] In the early days, the traditional system of subway galleries was maintained, although at the end of the 19th century surface mining, the so-called "cortas", began to be implemented.
[25] The expansion of mining activities meant the need for a greater number of workers, which would eventually lead to a profound change in the demography of the area.
[30] In the Filón Norte area mining was carried out in open pit and had an annual production of one million tons of ore. La Zarza, on the other hand, had subway counter-mining operations, with an annual production of about 400,000 tons of ore.[23] Another remarkable fact of this period was that, from then on, a considerable part of the pyrite obtained was no longer destined for export and began to be sent to the plants of the new Chemical Park of Huelva.
[35] At the end of the 20th century, the progressive fall in the price of copper in international markets made profitable mining unfeasible, which resulted in numerous losses.
[40] Since the reactivation of the basin in the 19th century, several industrial facilities have been built in connection with the extraction and processing of minerals: loading docks, winches, railway tracks, power plants, offices, reservoirs, etc.
At the end of the 19th century, TOS (Tharsis Sulphur and Copper Company Limited) built several reservoirs in the basin: Grande, Pino and Puerto León.
Over the years, an important railway complex was built in Tharsis, which had a locomotive depot, workshops and a wide track network for the classification of mining trains.
