The gold, silver and bronze metal in the London 2012 Olympic Games medals was mined after London Olympic Games organisers allowed its supplier Rio Tinto “to slip through the net”, an Olympic watchdog has found.
See http://www.telegraph.co.uk/sport/olympics/9341456/London-2012-Olympics-Rio-Tinto-allowed-to-start-production-of-Games-medals-without-audit.html#.