 Activities propelled by gold rushes define significant aspects of the culture of the Australian and North American frontiers.At a time when the world's money supply was based on gold, the newly-mined gold provided economic stimulus far beyond the gold fields, feeding into local and wider economic booms.Gold rushes occurred as early as the times of the Roman Empire, whose gold mining was described by Diodorus Siculus and Pliny the Elder, and probably further back to ancient Egypt.