There are different types of mining. One of the types that is commonly done is referred to as Placer mining. This is where mining is done for alluvial deposits of minerals.
Placer mining often refers to the type of mining done either by open pit techniques or by excavation methods. Placer mining is a term that comes from the Spanish language, Placera means “alluvial Sand” and it means mining for precious metal deposits such as gemstones and gold.
These materials are found in alluvial deposits, sand and gravel in ancient or modern stream beds. The metal has been moved by the water and deposited a distance from the original source of the metal, such as a vein or deposit over the water.
Sometimes placer mining is done using water to mine move and separate the precious metals from the surrounding deposit or sand and gravel.
Hydraulic methods of placer mining have been used since Roman times, but it was used during the North American Gold Rush in California, and the Fraser Canyon Gold Rush, as well as the Gold Rush of the Klondike.
One simple one person method of placer mining is panning, where a small amount of sand or gravel is put in a large metal pan and with a good deal of water agitated in a circle so that the gold will remain because it is dense and heavier, and the lighter sand and gravel will wash away.
Another method is to use a sluice box, with ridges along the bottom or barriers, a large amount of soil is place in the box and water allowed to wash down the box, and the gold will be trapped in the ridges along the bottom of the box.
Hydraulic Mining can do a lot of damage, and so it is widely restricted around the world.