mining valuable minerals from a placer by washing or dredging
Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment. Placer mining is frequently used for precious metal deposits and gemstones, both of which are often found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds, or occasionally glacial deposits. The metal or gemstones, having been moved by stream flow from an original source such as a vein, is typically only a minuscule portion of the total deposit. Since gems and heavy metals like gold are considerably more dense than sand, they tend to accumulate at the base of placer deposits. The containing material may be too loose to safely mine by tunneling, though it is possible where the ground is permanently frozen. Where water under pressure is available, it may be used to mine, move, and separate the precious material from the deposit, a method known as hydraulic mining, hydraulic sluicing or hydraulicking.
The numerical value of placer mining in Chaldean Numerology is: 5
The numerical value of placer mining in Pythagorean Numerology is: 4
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"placer mining." Definitions.net. STANDS4 LLC, 2017. Web. 21 Oct. 2017. <http://www.definitions.net/definition/placer mining>.