The Collaborative International Dictionary
Hushing \Hush"ing\, n. (Mining) The process of washing ore, or of uncovering mineral veins, by a heavy discharge of water from a reservoir; flushing; -- also called booming and hydraulic mining.
Wikipedia
Hydraulic mining, or hydraulicking, is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment. In the placer mining of gold or tin, the resulting water-sediment slurry is directed through sluice boxes to remove the gold. It is also used in mining kaolin and coal.
Hydraulic mining originated out of ancient Roman techniques that used water to excavate soft underground deposits. Its modern form, using pressurized water jets produced by a nozzle called a "monitor", came about in the 1850s during the California Gold Rush in the United States. Though successful in extracting gold-rich minerals, the widespread use of the process resulted in extensive environmental damage, such as increased flooding and erosion, and sediment blocking waterways and covering over farm fields. These problems led to its legal regulation. Hydraulic mining has since been used in various forms around the world.
Usage examples of "hydraulic mining".
They made a nice little ceremony of it, and just as the hydraulic mining machine started ramming through the topsoil somebody tossed a bomb from the crowd.
They hauled in Japanese hydraulic mining equipment and literally washed away [229] huge sections of the mountain.
Water had sculpted the sides into crazy formations that reminded her of hydraulic mining sites she'd seen once in California.
Well, the big news that week would be the arrival of a loaded immigrant ship from Thetis of Procyon, a planet whose ecology had been wrecked beyond repair in a few short generations by DDT, hydraulic mining, unrestricted logging, introduction of rabbits and house cats and the use of poison bait to kill varmints.