A river that runs blood-red, and one of the oldest mining districts on Earth. The Rio Tinto in Andalusia has been mined for copper, silver and gold for five thousand years, by Tartessians, Phoenicians and Romans, and the acid, iron-saturated water is so extreme that NASA studies its microbes as an analogue for life on Mars. The Roman and Victorian workings, and a mining railway, are open to visit. PUBLIC museum + train, Huelva.
Copper, sulphides, gossan
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Other places on the map within a couple of hours.