Minas de Tharsis — Malacate de Tharsis Alosno · Andalucía · Spain

The Malacate de Tharsis stands within the Tharsis mine complex in the Andévalo comarca of Huelva province, on the boundary of the municipality of Alosno. It is described in industrial heritage sources as the sole surviving water-drainage winding engine structure within the entire complex — a function indispensable to underground mining, as it served to pump and raise groundwater from the mine workings. The term malacate denotes a pyramidal wooden or metal structure, crowned by a pulley guiding a cable, used to raise or lower personnel, ore wagons, or water vessels from a shaft interior.

The Tharsis mine complex sits within the Iberian Pyritic Belt, a geological formation stretching from the Portuguese Alentejo eastward across Huelva province. Archaeological and material evidence attests to mining at Tharsis from prehistoric times, with particularly significant Roman workings attested across the area. Modern industrial exploitation began effectively in 1849 when Luciano Escobar visited the site and recognised the scale of ancient workings, though he could not assemble sufficient capital. In 1853 the French mining engineer Ernesto Deligny travelled to Huelva, visited the enormous ancient slag heaps, and formed a prospecting company called La Sabina, reopening works at the Filón Sur adit. A French company, the Compagnie des Mines de Cuivre de Huelva, was founded in 1855 to exploit the deposits; by 1858 some 2,500 workers were active in the Tharsis area, producing around 9,000 tonnes of ore per month. Financial difficulties and economic problems halted this phase, however.

In December 1866 the French company leased the mines to a British — more precisely Scottish — enterprise, the Tharsis Sulphur and Copper Company Limited (TOS), founded that year by Sir Charles Tennant and associates to take over the pyrite deposits. This transfer marked the beginning of the most productive and most extensively documented phase of Tharsis mining. TOS introduced modern extraction methods, began the systematic development of the open-cast cortas, and constructed a railway line — the Tharsis railway — between 1867 and 1870, opened to traffic in February 1871, connecting the mining basin to a purpose-built loading pier on the Odiel estuary at Corrales. The pier was built in 1866–1871 by engineers William Moore and James Pring to carry up to 2,500 tonnes of mineral per day, with simultaneous berthing capacity for three or four vessels.

Throughout the latter nineteenth century and the first half of the twentieth, TOS expanded operations considerably across the five principal cortas at Tharsis: Filón Norte (pyrite), Filón Sur or Corta del Oro (pyrite and gold-bearing gossan), Filón Centro (iron pyrite and copper pyrite), Corta Esperanza (copper shale), and Corta de Sierra Bullones (pyrite). Supporting infrastructure built during this period included a calcination zone, ore crushing plant, ore storage silos, a thermal power station, workshops, reservoirs, and extensive railway marshalling facilities. A Scottish-character company town was constructed to house British technical and managerial staff at Pueblo Nuevo, alongside workers' barracks and social facilities for the wider workforce.

The malacate served the drainage function within this underground complex. It is described as the only such drainage winding structure to survive in the Tharsis complex. A second malacate associated with the mine — the malacate of Sierra Bullones — was a prominent landmark of the Tharsis townscape but was scrapped for metal after the mines closed, a loss lamented in local memory.

In the 1970s the deposits and facilities began to pass from British to Spanish ownership. The Compañía Española de Minas de Tharsis operated from 1978, becoming by 1987 the leading pyrite seller in Spain. The closure of La Zarza operations in 1991 and the ending of sea mineral exports in 1993 progressively narrowed the company's commercial position. Persistent losses led to the cessation of operations by Compañía Española de Minas de Tharsis in December 1995, followed by bankruptcy and liquidation in April 1996. A workers' labour corporation, Nueva Tharsis, then took over direct management. The extraction of gossan at Filón Sur by the Canadian company Caledonia Mining continued until 2002. The main closure of Tharsis deposits was completed by 2001.

Following the end of mining activity, the industrial heritage of the site entered a period of progressive deterioration. Several structures were dismantled or stripped of components. The malacate de Tharsis survived this period, however, and alongside the Chimenea Gorda ventilation chimney, the ore crushing plant at Filón Norte, remains of the gold and silver processing plant at Filón Sur, ore discharge silos, an electrical substation, offices, and reservoirs, it forms part of the surviving industrial complex. In 2007 a mining museum — Colecciones de Tharsis — was established in the former company hospital in the Tharsis town centre, housing geological samples, mine machinery, documents, wooden foundry models, and railway vehicles from the company's El Viajero passenger train. The historical company archive, one of the most significant mining company archives in Spain, is also housed there. In 2014 the Junta de Andalucía inscribed the Cuenca Minera de Tharsis-La Zarza in the Catálogo General del Patrimonio Histórico Andaluz with the designation of Zona Patrimonial, covering 1,321.5 hectares and providing legal protection for the malacate and the wider complex.