Going off the topic a bit , this is something interesting I read recently . A joint group from the Tokyo Institute of Technology and the National Institute of Advanced Industrial Science and Technology (AIST) has devised a way to enhance the extraction process of gold from electronic components.
Gold, platinum and other precious metals are used in components for PCs, mobile phones and other electronic goods . But recovering these valuable minerals once the hardware is retired has never been cost effective or practical at a large scale, so there are currently trillions of micro sized gold nuggets hidden in refuse and landfill sites. The new process involves dissolving the metals from old electronic products in acid, extracting the precious metals into a second liquid and then recovering them using plant-derived tannin,By using a sulphide-type diamide as the extracting agent, the group is able to extract over 50 per cent of the gold from the acid solution !!!.
So no more throwing away old parts as there is gold to be found in them 🙂

Wikipedia on digger gold