In a single South African gold mine, an expected $2.2bn worth of gold can still be extracted from just one dump site's waste material.
Using water cannons and chemical treatments, a single mine can hope to extract about 3 grams in every tonne. It may not sound like much, but if there is 140 million tonnes of waste lying around - the numbers start adding up.
High prices mean all the effort that goes into sourcing the precious metal may well be worth it.
Al Jazeera's Tania Page reports from Johannesburg.
Source: Al Jazeera