The Professor discusses new research suggesting why gold (among other dense metals) is found close to the Earth's surface. Our thanks to everyone at the Central Deborah Gold Mine in Bendigo, especially Joel. http://www.central-deborah.com/ More chemistry at http://www.periodicvideos.com/ Follow us on Facebook at http://www.facebook.com/periodicvideos And on Twitter at http://twitter.com/periodicvideos Periodic Videos films are by video journalist Brady Haran