As he writes in Open Science, he suspects these are found beneath every active and dormant volcano, though the concentration of copper in the brine concerned will vary from place to place.His evidence comes from electromagnetic surveys carried out on some 40 volcanoes, including Mount Fuji in Japan, Mount St Helens in America and others in Bolivia, New Zealand, the Philippines and elsewhere.These surveys consistently pick up highly conductive zones 2km or more beneath the surface, for which the simplest explanation is the presence of super-salty metalrich brines.This conjecture is reinforced by analysis of rock samples recovered from such depths under a number of volcanoes.These do indeed contain brines with varying concentrations of copper, as well as other valuable metals including lithium, ZINC, gold and silver.All this suggests that copper could be drilled for commercially in the same way that oil is―except that the boreholes involved would be considerably deeper.That would be difficult, but not out of the question.It would require equipment that could withstand temperatures greater than 400°C and contact with brines ten times saltier than seawater. But the prize would be worth it.
