The Rio Tinto is a river in Andalusia, Spain. It originates in the Sierra Morena mountains and flows into the Gulf of Cádiz in Huelva. The site along the Rio Tinto river is full of copper, silver, gold, iron and other minerals. Due to the site being heavily mined for those minerals over ages since the ancient times the river is full of minerals, espacially iron - therefore the reddish colour of the river and the riverside. The river is unique both in its outlook and in its environmental state. According to the Wikipedia the river is researched by astrobiologists as its extreme conditions "may be analogous to other locations in the solar system".