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How is gold recovered from alluvial deposits with gravity separation?

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A diagram showing the periodic table entry for gold, with the symbol Au, atomic number 79, atomic weight 196.96657, electron configuration, and labels for its properties as a solid transition metal with a face-centered cubic crystal structure. — gold The precious metal gold is a chemical element with the symbol Au. Its square on the periodic table details some of its properties, including its atomic weight, atomic number, and crystal structure.

Gravity separation is a primary method for recovering gold from alluvial deposits because it exploits the high density of gold, which causes it to sink more rapidly than lighter materials like sand and gravel.12

Common gravity techniques include:

Panning: A manual method where a mixture of water and gold-bearing material is swirled in a pan. The motion allows heavy gold to settle at the bottom while lighter material is washed over the edge.32
Sluicing: Gold-bearing gravel is carried by water through a sloping trough or channel. Transverse riffles along the bottom create eddies that trap the heavy gold particles while allowing lighter waste to pass.2
Jigging: A water stream is pulsed upward and downward through a bed of material, causing it to stratify by density, with the heaviest gold forming the lowest layer.41
Tabling: A slurry is passed over grooved or ridged tables that are vibrated. This motion separates the material into layers, retaining the dense gold particles.41
Spirals: Pulp flows down a vertical spiral channel, where heavier particles concentrate on the inner side of the stream for removal.4