Seperating out the fine gold can be a lot of work and there are several methods for doing it.  From drying the black sands out and using a magnet to remove out the metals other than gold, to amalgamation, the method of using mercury to take the gold out of the remaining black sands.  BE CAREFUL AND MAKE SURE YOU KNOW WHAT YOU ARE DOING! The Gold Prospectors Association is a great resource and you can find them online.