Hydraulic mining Wikipedia
A miner using a hydraulic jet to mine for gold in California, from The Century Magazine January 1883. Hydraulic mining is a form of mining that uses highpressure jets of water to dislodge rock material or move sediment. In the placer mining of gold or tin, the resulting watersediment slurry is directed through sluice boxes to remove the gold. It is also used in mining kaolin and coal.