Figure . A) Gold mining relies on the use of toxic substances such as cyanide in formal mining and mercury in artisanal and small-scale gold mining (ASGM). Recycling gold from electronic waste ("urban mining") is complicated by the complex composition of printed circuit boards and other components of obsolete electronic devices. Images were reproduced under creative commons licenses . B) An integrated approach to mercury-and cyanide-free gold recovery from both primary and secondary gold sources reported in this study.