A rush typically begins with the discovery of placer gold made by an individual. At first the gold may be washed from the sand and gravel by individual miners with little training, using a gold pan or similar simple instrument. Once it is clear that the volume of gold-bearing sediment is larger than a few cubic metres, the placer miners will build rockers or sluice boxes, with which a small group can wash gold from the sediment many times faster than using gold pans. Winning the gold in this manner requires almost no capital investment, only a simple pan or equipment that may be built on the spot, and only simple organisation. The low investment, the high value per unit weight of gold, and the ability of gold dust and gold nuggets to serve as a medium of exchange, allow placer gold rushes to occur even in remote locations.