Hydraulic mining, or hydraulicking, is a form of mining that employs water under pressure to dislodge rock material or move sediment. This form of mining was first used by Edward Matteson near Nevada City, California, in 1853 to exploit gold-bearing upland paleogravels. Previously hydraulicking had been developed by the Romans to find gold using water streams from tanks to remove overburden and then gold-bearing debris as in Las Médulas of Spain, and Dolaucothi in Britain. The method was used in Elizabethan Britain for developing lead, tin and copper mines, and became known as hushing.
In California, hydraulic mining often applied water under very high pressures developed by bringing water from high Sierra locations for long distances along ridge crests to holding ponds several hundred feet above the surface to be mined. Insofar as California hydraulic mining exploited primarily river gravels, it was one form of placer mining; that is, working of alluvium (river sediments).
