Sluices

Sluices are long, narrow "boxes" that water passes through when put in a creek or stream. Nineteenth century gold miners used wooden varieties, but modern gold prospectors primarily use sluice boxes made of metal with miner's moss in the bottom for trapping gold. The idea is to position a sluice box in a running stream so that the water does the work-- separating the dirt and rocks away from the gold. Since gold is heavy, it will stay in the bottom of the sluice, trapped in the miner's moss.