River Enguri in Upper Svaneti was known from ancient times as gold containing river. From ancient times people of Svaneti were known as gold seekers. In old times sheep skin was used for gold washing in rivers, and myth about Argonauts, famous golden fleece is exactly from Svaneti, Enguri river.
Even now tourists may see and participate in gold washing. Best known villages for this are Latali, Tskhumari and Ieli. Now there is not much gold in Svaneti, but if you are lucky there is a chance to find few.