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The name is from the Spanish word placer, meaning "alluvial sand". Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, aeolian placers and paleo-placers. [2]
For example; the medium-sized Coburn mineral sands deposit, Western Australia, is 230 million tonnes at 1.1% heavy minerals, and is 13 km long. The Tormin mine, on the Western Cape of South Africa's coastline, provides a unique ocean beach feature, which exposes the resource to wave and tidal conditions that result in a natural jigging effect.
Placer mining is frequently used for precious metal deposits (particularly gold) 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, are ...
Sedimentary placer deposits are known as 'leads' or 'deep leads'. Placer deposits are often worked by fossicking, and panning for gold is a popular pastime. Laterite gold deposits are formed from pre-existing gold deposits (including some placer deposits) during prolonged weathering of the bedrock. Gold is deposited within iron oxides in the ...
Orogenic gold deposits are responsible for approximately 75% of the world's gold production at over 1 billion ounces, when accounting that the origin of many gold placer deposits were orogenic in nature. [25] [46] The price of gold at a given time will have an impact on whether a deposit will be economically feasible.
This method involved digging a shaft 6 to 13 meters (20 to 43 ft) deep into placer deposits along a stream. Tunnels were then dug in all directions to reach the richest veins of pay dirt. In the most complex placer mining, groups of prospectors would divert the water from an entire river into a sluice alongside the river, and then dig for gold ...
Hydraulic gold mining in Alder Gulch, 1871. Photo by William Henry Jackson. Placer mining in Alder Gulch, 1872. Alder Gulch (alternatively called Alder Creek) is a place in the Ruby River valley, in the U.S. state of Montana, where gold was discovered on May 26, 1863, by William Fairweather and a group of men including Barney Hughes, Thomas Cover, Henry Rodgers, Henry Edgar and Bill Sweeney ...
Mining Claim Corner, Blue Ribbon Mine, Alaska. A placer claim is a mining claim on gravel or ground from which minerals are extracted using water. [1] In the United States, the valuable mineral in a placer claim is almost always gold, although other nations mine placer deposits of platinum, tin, and diamonds.