Science & technology
People may one day drill for copper as they now drill for oil
Copper was the first metal worked by human beings. They hammered it into jewellery and ornaments as much as 11,000 years ago. Today, Homo sapiens uses more than 20m tonnes of the stuff a year, much of it in buildings and electrical infrastructure. More will be required in coming decades, to meet the need for widespread electrification brought about by the transition to less carbon-intensive economies. Copper is an essential part of batteries, motors and charging equipment. Solar and wind installations use more copper than their fossil-fuel counterparts, and electric vehicles contain four times more copper than do cars with combustion engines.
This has spurred interest in new sources of the metal, most of which comes at the moment from rocks dug out of vast opencast mines that are then ground up and processed to release the copper they contain, typically about 1% of their mass.
Metal-rich nodules scattered across various parts of the ocean floor are a possibility. But exploiting these brings technological and regulatory difficulties, and is in any case controversial because of the damage it would do to deep-ocean ecosystems. Jon Blundy of Oxford University, however, offers an alternative. This is to extract, from deep under Earth's surface, the mineral-rich brines from which ores of copper and other valuable metals are generated in the first place. As Dr Blundy points out, "pretty much all of the non-ferrous natural resources that we exploit come ultimately from ancient volcanoes."
In particular, in 2015, he and his colleagues worked out the chemical details of how copper-sulphide ores form when sulphur-rich gases rise through the plumbing of active volcanoes and encounter metalrich brines trapped in rocks sitting just above pockets of magma. Modern mining operations dig up examples of these ores that formed millions or billions of years ago. Dr Blundy proposes instead to cut out the middleman and go straight to the deep copper-rich fluids themselves.