Mineral-laden water in the Rio Tinto in Minas de Rio Tinto mining area, Huelva province, Andalusia, Spain

Reflecting on the Rio Tinto. The strange hues of the Rio Tinto

This surreal landscape can be found in Andalusia, in south-west Spain, where high levels of iron and sulphur have turned this acidic river red. The Rio Tinto (Red River) may owe its chemical composition to 5,000-years or more of mining in the area. Ancient residents from the Tartessians, who lived in the area from around the 10th century BCE, and the Romans, dug for copper, silver and gold here - as well as the mineral pyrite, commonly referred to as 'fool's gold’. Legend has it that Rio Tinto was the site of the fabled mines of King Solomon.

Its extreme acidity means the river and surrounding areas are not hospitable places for the sort of plant life you might usually find in and along the riverbeds of Spain. Only unusual microorganisms, classified as extremophiles, can survive the water's acidic mix, by feeding on the minerals alone. Rio Tinto's strange ecology has attracted the attention of Nasa, which has studied the bacteria that have adapted to this highly acidic environment because the conditions resemble those on the surface of Mars.