Copper, gold, silver and other minerals have been mined along the river for the past 5000 years. The Red River is considered one of the birthplaces of both the Copper Age and the Bronze Age. Mining began in the region in 3000BCE by the Iberians and the Tartessians. They were followed by the Phoenicians, Greeks, Romans, Visigoths and Moors. The mines were rediscovered by Spain in 1556 and reopened in 1724; they were sold to the British in 1871.
The Rio Tinto Corporation formed to operate the mines after large scale excavations by companies from the United Kingdom were thought to make the river highly aciditic (pH 1.7-2.5). It is possible that the presence of chemolithotrophic organisms, such as iron-oxidizing bacteria and sulphur-oxidizing bacteria, may be the true culprits for the river's condition. There is also a large amount of eukaryotic diversity in the acidic water; the eukaryotes are both alkaliphilic and toxitolerant and far more diverse than the prokaryotes.
These extremophile aerobic bacteria provide conditions similar to those seen on other bodies within our Solar System. Europa, a moon of Jupiter, is thought to contain an acidic ocean underneath its surface; the extremophiles which life off the iron and sulphide minerals in Rio Tinto’s subsurface rocks may well be similar to potential life on Europa.
Rio Tinto was an expedition target for the Mars Analog Research and Technology Experiment (MARTE), starting in 2003. Rio Tinto is found in the Iberian Pyrite Belt, which is a large deposit of sulfide minerals formed in the Carboniferous (300-350 Ma) by hydrothermal activities on the sea floor. As volcanoes and ground ice are found on Mars, it is possible that hydrothermal systems could also have formed there. Mars is rich in iron and sulphur, which are key for the formation of sulfide minerals and also appears to have widespread basaltic volcanism. Sulfide minerals on Earth are made in hydrothermal systems associated with basaltic volcanism; therefore the rationale behind the MARTE drilling is that the mineral deposits in Rio Tinto may be found in the Martian subsurface.
The Austrian Space Forum also tested a space suit and a prototype unmanned rover, named Eurobot, within the arid area of Rio Tinto.
Photo by Francisco Mingorance ,http://i.telegraph.co.uk/