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box, being fed not by a sluice but by hand. The box sits on rockers, which when rocked separates out the gold, and the practice was referred to as "rocking the golden baby". A typical rocker box is approximately 42 inches long, 16 inches wide and 12 inches deep with a removable tray towards the top, where gold is captured. The rocker was commonly used throughout North
America during the early gold rush, but its popularity diminished as other methods that could handle a larger volume became more common.
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643:". This method was most commonly used by Spanish miners in America, and only requires a blanket and a box with a screen on the bottom. The material is first filtered through the box so only the finer material is placed onto the blanket. The material on the blanket is then flung into the air so that any breeze can blow away the lighter material and leave the gold behind. While this method is extremely simple and requires very few materials, it is also slow and inefficient.
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under pressure, is provided to the scrubber and screen sections and the combination of water and mechanical action frees the valuable heavy minerals from the lighter gravel. The mineral bearing ore that passes through the screen is then further concentrated in smaller devices such as sluices and jigs. The larger pieces of ore that do not pass through the screen can be carried to a waste stack by a conveyor.
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placing gravel on a riffle board with a bellows placed underneath it. The bellows is then used to blow air through the board in order to remove the lighter material from the heavier gold. The amount of gravel that can be processed using the
Mexican dry wash technique varies from 1 1/2 to 4 cubic yards per day, and can be processed at a maximum efficiency of 80%. Another form of dry washing is "
726:, such as in Siberia, Alaska, and the Yukon, placer deposits may be mined underground. As the frozen ground is otherwise too hard and firm to mine by hand, historically fires were built so as to thaw the ground before digging it. Later methods involve blasting jets of steam ("points") into the frozen deposits.
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Although this procedure is not required, the process water may be continuously recycled and the ore from which the sought-after minerals have been extracted ("the tailings") can be reclaimed. While these recycling and reclamation processes are more common in modern placer mining operations they are
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or similar implements to feed ore into the device. Sluice boxes can be as short as a few feet, or more than ten feet (a common term for one that is over six feet +/- is a "Long Tom"). While they are capable of handling a larger volume of material than simpler methods such as the rocker box or gold
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Bench deposits are created when gold reaches a stream bed. Gold accumulations in an old stream bed that are high are called bench deposits. They can be found on higher slopes that drain into valleys. Dry stream beds (benches) can be situated far from other water sources and can sometimes be found
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An area well protected from the flow of water is a great location to find gold. Gold is very dense and is often found in a stream bed. Many different gold deposits are dealt with in different ways. Placer deposits attract many prospectors because their costs are very low. There are many different
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material such as sand, mud and gravel are then washed over the side of the pan, leaving the gold behind. Once a placer deposit is located by gold panning, the miner usually shifts to equipment that can treat volumes of sand and gravel more quickly and efficiently. Gold panning was commonly used on
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and drives similar to underground mining techniques but is typically processed as if alluvial gold. The heat associated with an igneous lava flow, in some cases, altered the gold bearing gravel so that it needed to be crushed first to extract the gold; an example of this kind of deep lead was found
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Alluvial or eluvial deposits are the most common type of placer gold, and are often the richest. They contain pieces of gold that have been washed away from the lode by the force of water, and have been deposited in sediment in or near watercourses or former watercourses. Therefore, they are mostly
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Large-scale sifting of placer gold from large volumes of alluvial deposits can be done by use of mechanical dredges. These dredges were originally very large boats capable of processing massive amounts of material; however, as the gold has become increasingly depleted in the most easily accessible
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A rocker box (or "cradle") is capable of greater volume than a gold pan; however, its production is still limited when compared to other methods of placer mining. It is only capable of processing about 3 or 4 yards of gravel a day. It is more portable and requires less infrastructure than a sluice
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is composed of a slightly inclined rotating metal tube (the 'scrubber section') with a screen at its discharge end. Lifter bars, sometimes in the form of bolted in angle iron, are attached to the interior of the scrubber section. The ore is fed into the elevated end of the trommel. Water, often
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Sluicing is only effective in areas where there is a sufficient water supply, and is impractical in arid areas. Alternative methods developed that used the blowing of air to separate out gold from sand. One of the more common methods of dry washing is the
Mexican dry wash. This method involves
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for larger scale operations. When streams became increasingly depleted, the grizzly and undercurrent variants of the sluice box were developed. The grizzly is a set of parallel bars placed at a 45-degree angle over the main sluice box, which filter out larger material. The undercurrent variety
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Residual deposits are more common where there has been weathering on rocks and where there hasn't been water. They are deposits which have not been washed away yet or been moved. The residual usually lies at the site of the lode. This type of deposit undergoes rock weathering.
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includes additional, auxiliary sluice boxes where material is initially filtered. It then travels through a trough into the primary sluice box where it is filtered again. Both the grizzly and undercurrent are designed to increase efficiency, and were often used in combination.
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areas, smaller and more maneuverable dredges have become much more common. These smaller dredges commonly operate by sucking water and gravel up through long hoses using a pump, where the gold can then be separated using more traditional methods such as a sluice box.
210:, or occasionally glacial deposits. The metal or gemstones, having been moved by stream flow from an original source such as a vein, are typically only a minuscule portion of the total deposit. Since gems and heavy metals like gold are considerably denser than
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metals in a very large proportion of gold items indicate that the gold was largely derived from placer or alluvial deposits. Platinum group metals are seldom found with gold in hardrock reef or vein deposits.
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form of placer mining as environmentally destructive because of the large amounts of silt that it adds to previously clear running streams (also known as the "Dahlonega Method"). Most placer mines today use
469:, also in Australia. If vegetation was buried along with the old stream, by a volcanic eruption, the effect of heat and decay upon that buried vegetation can result in the presence of harmful amounts of
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In
California, from 1853 to 1884, "hydraulicking" of placers removed an enormous amount of material from the gold fields, material that was carried downstream and raised the level of portions of the
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Placer deposits can be as young as a few years old, such as the
Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliot Lake uranium paleoplacer within the
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in the region and so probably witnessed large-scale hydraulic mining of the placer deposits there. He also added that the local lake
Carucedo had been heavily silted by the mining methods.
603:, with barriers along the bottom called riffles to trap the heavier gold particles as water washes them and the other material along the box. This method better suits excavation with
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529:. This technique has been dated back to at least the Roman Empire. In panning, some mined ore is placed in a large metal or plastic pan, combined with a generous amount of
546:; however, it is now rarely used for profit since even an expert gold prospector can only process approximately one cubic yard of material for every 10 hours of work.
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A number of methods are used to mine placer gold and gems, both in terms of extracting the minerals from the ground, and separating it from the non-gold or non-gems.
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Deep leads are created when a former stream bed is covered over by later sediments or by igneous rock from a volcanic eruption. Examples existed in the goldfields of
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panning, this can come at the cost of efficiency, since conventional sluice boxes have been found to recover only about 40% of the gold that they process.
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in South Africa is an example of a placer deposit, as it is a 3 billion-year-old, alluvial sedimentary basin containing at least 70 ore minerals.
228:. 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
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The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it is possible where the ground is
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case banned the flushing of debris into streams, and the hydraulic mining mania in
California's gold country came to an end.
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Placer mine worker streams high pressure water to assist with mining operations in Park County, Colorado, early 1900s
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Placer mining continues in many areas of the world as a source of diamonds, industrial minerals and metals, gems (in
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In earlier times the process water was not generally recycled and the spent ore was not reclaimed. The remains of a
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1408:"What Was the Klondike Gold Rush? – Klondike Gold Rush National Historical Park (U.S. National Park Service)"
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808:. The process raised an opposition calling themselves the "Anti-Debris Association". In January 1884, the
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Placers supplied most of the gold for a large part of the ancient world. Hydraulic mining methods such as
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A modern sluice box made of metal; in its base are the riffles used to catch gold settling to the bottom
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were used widely by the Romans across their empire, but especially in the gold fields of northern
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by some seven feet in affected areas and settled in long bars up to 20 feet thick in parts of
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placer mining deposit, which it soon became when 30,000 gold-seekers trekked to the region.
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Subasinghe, G. K. N. S. (1993). "Optimal Design of Sluice-Boxes for Fine Gold
Recovery".
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Placer mines in Park County, Colorado, 1870s. A long sluice box runs along the mine.
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places gold could be placed, such as a residual, alluvial, and a bench deposit.
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Basque, G. (1999). Methods of placer mining. Surrey, B.C: Heritage House. p. 41
851:. The nuggets were found in running water, making the Klondike Gold deposit an
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on mountaintops. Today, many miners focus their activities on bench deposits.
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930:"Placer mining | Techniques, Processes & Equipment | Britannica"
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in a sluice box. The small specks are gold, the larger ones are merely pebbles
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The same principle may be employed on a larger scale by constructing a short
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1053:"Buried Rivers of Gold Heritage Trail | Business & Tourism Creswick Inc"
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A.D. McCracken, E. Macey, J.M. Monro Gray, and G.S. Nowlan (March 1, 2018).
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which, when rocked back and forth, will help separate gold dust from the
1326:
Placer Mining: A Hand-Book for
Klondike and Other Miners and Prospectors
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began in 1896 when nuggets of gold were found in the
Klondike region of
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are accessed by techniques similar to conventional underground mining.
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than the other material, settle to the bottom of the pan. The lighter
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status. The methods used by the Roman miners are described by
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are so spectacular as to justify the site being designated
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The simplest technique to extract gold from placer ore is
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deposits—deposits of sand and gravel in modern or ancient
1329:. Scranton, Pa.: Colliery Engineering Co. 1897. pp.
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569:"Sluice box" redirects here. For the general topic, see
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An alternative etymology derives the English word from
1463:. Baton Rouge: Louisiana State University Press 1952.
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The Natomas No. 6 gold dredge in operation in 1958 in
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in Australia. The gold bearing gravel is accessed by
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Technique of mining stream bed deposits for minerals
1172:. Oklahoma: University of Oklahoma Press. pp.
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60:. Unsourced material may be challenged and removed.
1282:Finding Gold in the Desert: the Art of Dry-Washing
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319:Plate depicting placer mining from the 1556 book
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619:The sluice box was used extensively during the
255:, meaning shoal or alluvial/sand deposit, from
1299:. Reno, Nevada: University of Nevada Bulletin.
352:gold deposits through the first century AD.
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1374:. California Parks and Recreation Department
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968:: CS1 maint: multiple names: authors list (
781:published in about 77 AD. The author was a
179:) is the mining of stream bed deposits for
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810:North Bloomfield Mining and Gravel Company
340:in 25 BC. One of the largest sites was at
1310:Park County Local History Digital Archive
1269:Park County Local History Digital Archive
120:Learn how and when to remove this message
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834:Colony of British Columbia (1858–1866)
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1347:Dahlonega, Georgia: a brief history
1105:Australian Town and Country Journal
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1461:Colonial Placer Mining in Colombia
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1394:"Chamber of Mines of South Africa"
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1077:"Buried Rivers of Gold | Creswick"
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984:"Placers etymology and definition"
435:found in valleys or flood plains.
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296:(placer, sandbank), from earlier
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910:. American English Dictionary
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655:Trommel at the Potato Patch,
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877:British Columbia gold rushes
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573:. For the Montana park, see
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1297:Placer Mining in Nevada
986:. Thefreedictionary.com
830:Fraser Canyon Gold Rush
575:Sluice Boxes State Park
373:Fraser Canyon Gold Rush
194:deposits (particularly
1344:Amerson, Anne (2006).
1151:Roman Deep Vein Mining
1006:"placer in Wiktionary"
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1126:"The Dark Labyrinth"
908:"Placer mining (US)"
621:California gold rush
544:California gold rush
517:Panning for gold in
365:California Gold Rush
307:(placer, sandbank).
54:improve this article
1551:Mountaintop removal
1248:1993MiEng...6.1155S
1210:Basque, G. (1999).
1008:. en.wiktionary.org
823:Witwatersrand Basin
542:its own during the
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1280:Lynch, O. (2001).
1130:Buried Rivers Gold
1081:Buried Rivers Gold
1032:www.geomaps.com.au
934:www.britannica.com
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841:Klondike Gold Rush
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43:This article
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18:Alluvial gold
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964:cite journal
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52:Please help
47:verification
44:
1709:Gold mining
1678:Prospecting
1560:Sub-surface
1412:www.nps.gov
763:Las Médulas
752:Las Médulas
678:Gold dredge
672:Gold dredge
628:Dry washing
361:gold rushes
342:Las Médulas
221:in Canada.
208:stream beds
1698:Categories
1588:Directions
1506:techniques
1135:2023-11-01
1111:2023-05-15
1086:2023-11-01
1062:2021-01-22
1037:2023-09-05
1012:August 18,
914:January 9,
894:References
783:Procurator
731:Deep leads
716:permafrost
601:sluice box
565:Sluice box
556:Rocker box
448:Deep leads
302:Portuguese
138:rocker box
80:newspapers
1668:Automated
1663:Abandoned
1579:Soft rock
1574:Hard rock
1526:Quarrying
641:winnowing
634:Drywasher
521:, c. 1900
388:Sri Lanka
346:aqueducts
244:Etymology
200:gemstones
1638:Longwall
1615:Borehole
1610:Bell pit
1541:Dredging
1521:Open-pit
1378:21 April
990:July 20,
860:See also
853:alluvial
816:Examples
750:View of
659:, Alaska
458:Creswick
430:Alluvial
421:Residual
406:Deposits
375:and the
367:and the
350:alluvial
338:Augustus
272:alluvial
234:sluicing
204:alluvial
181:minerals
142:alluvium
1643:Retreat
1625:Stoping
1567:Classes
1513:Surface
1244:Bibcode
665:trommel
647:Trommel
605:shovels
585:Riffles
535:density
527:panning
503:Panning
495:Methods
454:Gulgong
384:Myanmar
330:hushing
311:History
285:in 1880
250:Spanish
94:scholar
1536:Placer
1504:Mining
1354:
1180:
1176:–110.
845:Alaska
571:sluice
550:Rocker
539:gangue
462:shafts
396:Alaska
371:, the
305:placel
298:placel
294:placer
268:placea
264:placea
257:plassa
253:placer
198:) and
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1656:Other
1605:Shaft
1600:Slope
1595:Drift
1531:Strip
1423:Notes
952:(PDF)
767:Spain
759:Roman
531:water
519:Korea
439:Bench
392:Yukon
334:Spain
101:JSTOR
87:books
1380:2019
1352:ISBN
1333:–69.
1178:ISBN
1014:2019
992:2013
970:link
916:2015
839:The
828:The
821:The
456:and
398:and
386:and
212:sand
196:gold
73:news
1252:doi
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465:at
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355:In
236:or
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