Export of the metal is essential for Chile's economy - it amounts to about 70% of all Chilean exports - and the more copper the country digs out, the more money pours in. But even when a mine is estimated to contain high-grade ores, the bulk of the material coming out of the pit has a grade below 1%, and is usually discarded as waste.
Unless mini-miners come to help - microbes. Biosigma is a biotechnology venture set up by Codelco, a Chilean state-owned corporation and the largest copper mining company in the world, together with Japanese firm Nippon Metals and Mining. The bacteria are used to extract copper from rocks, replacing extreme heat and toxic chemicals.