The sluice was a long, downward-sloping trough. Water ran from the high end to the low, carrying along gravel shovelled in at the top. Gold settled from the mixture as it flowed, lodging behind riffles. In hydraulicking, banks of gold-bearing gravel were broken down and driven through sluices by jets of water. Hydraulicking, however, is highly destructive to land downstream from the mine.
Conservation laws prohibit it in many regions.
In a device akin to the sluice, a sand-water mixture may be flowed across sheets of corduroy fabric. The corrugations entrap the descending gold while the gangue flows on. The Golden Fleece of legend, sought by the Argonauts, was probably a sheepskin that had been similarly employed. Gold amalgamates with mercury on contact. Further, mercury is strongly attracted to itself.