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	Placer mining - Wikipedia, the free encyclopedia
		Placer mining (pronounced "plass-er") is a open-pit or open-cast form of mining by which certain valuable minerals are extracted from the earth without tunneling.
		Where water is available, hydrostatic pressure is used to mine, move, and separate the precious material from the deposit.
		Platinum-group metals are seldom, if ever, found with gold in reef or vein deposits.) In the United States, placer mining was famous in the context of several gold rushes, particularly the California gold rush.
	en.wikipedia.org /wiki/Placer_mining (381 words)

	Case study on Marcopper Mining
		Placer Dome executives met regularly with Canadian NGOs during the 1980s over this issue but the dumping was not halted until the Tapian Mine was depleted in 1991.
		Placer Dome continues to deny damage to the bay and nearby villagers as a result of the tailings.
		Placer Dome's first permit for ocean dumping explicitly stipulated that the dumping had to be submerged to protect marine resources.
	www.minesandcommunities.org /Company/marcopper1.htm (2022 words)

	California Gold Mining Terms and Procedures - 1876
		Thus originate the “river-bed claims,” to mine which the streams are turned from their courses; “bar-claims,” where the gold is mined at low water; “bench-claims,” where the bars are on narrow table-lands, once the beds of rivers; and “flat-claims,” where the wash of rivers has been spread over a level space of country.
		According as the “pay-dirt” is near the surface, or remote from it, placer mines are shallow, or deep.
		Before describing the modes of mining at present generally adopted, it will not be amiss to state the methods of obtaining the gold in the “Fall of ‘49 and the Spring of ‘50.” It was not until about 1852 that what has become known as hydraulic mining was begun.
	www.sfmuseum.org /hist9/turrillgold.html (4309 words)

	Placer mining (from mining) -- Encyclopædia Britannica (Site not responding. Last check: 2007-11-05)
		Placer mining takes advantage of gold's high density, which causes it to sink more rapidly from moving water than the lighter siliceous materials with which it is found.
		In the hydraulic mining of gold, the rebounding stream of water and mineral fragments is directed into sluices in which the gold settles behind baffles but the lighter waste matter is washed away.
		Contrasting types of mining include the open pits of the Lake Superior iron ranges, the bituminous coal mines in the Appalachian fields, and placer mining for tin in Malaya.
	www.britannica.com /eb/article-81283?tocId=81283 (925 words)

	EPA Biodiversity - Placer Mining (Site not responding. Last check: 2007-11-05)
		Placer mining, a mining technique used to remove metals (i.e., gold) embedded in stream and/or river bottom sediments, has proven to be detrimental to freshwater biodiversity.
		Placer mining operations utilize suction dredges to remove sediment, completely destroying the stream and/or river bottoms down to their underlying bedrock layer.
		Placer mining completely destroys important river and stream bottom habitats that are heavily relied upon by organisms as spawning and breeding grounds.
	www.epa.gov /bioindicators/aquatic/mining.html (253 words)

	CVO Website - Mining History around Mount St. Helens
		Placer gold was found in several of the district's streams; however the deposits proved to be small and unprofitable to mine.
		However, in 1905, 14 tons of copper ore from the Sweden Mine was laboriously dragged from the mine to Spirit Lake, loaded on a makeshift barge, towed to the western end of the lake, and hauled to the railroad for shipment to the Tacoma smelter.
		In 1905, the mine produced 13 tons of copper ore valued at $286; the copper was donated by Dr. H.W. Coe, president of Mount St. Helens Consolidated Mining Co., for the statue of Sacajawea erected at the 1905 Lewis and Clark fair in Portland.
	vulcan.wr.usgs.gov /Volcanoes/MSH/MineralResources/msh_mining_history.html (2233 words)

	www.mineweb.net \| sections \| sustainable mining Placer Dome is latest Oxfam target (Site not responding. Last check: 2007-11-05)
		Placer Dome contends that, after spending $70 million to remedy the situation plus $1.5 million in compensation to residents along the river, any remaining issues "were and remain the express responsibility of the mine's owner and operator" Marcopper Mining.
		Placer Dome has requested that it be removed from the directive and that these issues be addressed by the mine's owner and operator.
		Placer Dome argues that it "contained the problem, remediated the effects of the accident, compensated those affect and worked diligently to be a positive presence on the island of Marinduque in the absence of any other party willing to able to provide the necessary work and funding."
	www.mineweb.net /sections/sustainable_mining/425032.htm (962 words)

	Brief History of Placer County -- Placer County, Calif.
		Placer County was home to the peaceful Nisenan Native Americans for hundreds of years before the discovery of gold in 1848 brought hordes of miners from around the world.
		Gold mining was a major industry through the 1880s, but gradually the new residents turned to farming the fertile foothill soil, harvesting timber and working for the Southern Pacific Railroad.
		The cornerstone of Placer's beautiful and historic courthouse, which is clearly visible from Interstate 80 through Auburn, was laid on July 4, 1894.
	www.placer.ca.gov /museum/history.htm (492 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		Placer mining(pronounced plass-er) is a technique of mining by which valuable materials are extracted with little or no excavation.
		Ore extraction usually requires excavation, but precious deposits such as gold are so highly prized in even minuscule amounts that placer mining becomes feasible.
		In the United States, placer mining is famous in the context of several gold rushes, particularly the California gold rush.
	www.informationgenius.com /encyclopedia/p/pl/placer_mining.html (191 words)

	Impacts of Placer Gold Mining on the Red Book Species of Mongolia. (Site not responding. Last check: 2007-11-05)
		A placer gold rush is the main growth element in the Mongolian economy, with over 100 companies in production and national gold output rising every year for more than a decade to more than 11 tons a year.
		Attention is drawn to the lack of relevance to regional and local administrative boundaries to the mining boom in a 60km stretch of the Tuul Valley.
		The bulk of the placer gold occurs in the world-class Tuul Placer that is generally under the width of the Tuul floodplain, and therefore river diversions are routine in order to mine the placer.
	www.mine.mn /WPJ3_9_Satellite.htm (577 words)

	Placer Mining Facts - The Klondike Placer Miners' Association
		Placer mining and its' history continues to be a major tourist attraction in the Yukon.
		Placer claims and leases cover less than 0.2% of the Yukon land base and affect less than 2.5% of the water courses.
		Placer Mining Land Use Regulations can be found on the DIAND web site.
	www.kpma.ca /placerfacts.htm (500 words)

	Hydraulic Mining - CPRR Photographic History Museum
		North of the hard-rock mining area of the Mother Lode, immense quantities of placer gold lay embedded in banks of river gravels deposited during the dinosaur (Tertiary) era.
		Drift mining (tunneling into the bottom of the Tertiary gravel beds) was a costly and risky way to reach the richest deposits, but most of the gold was scattered as fines throughout the gravels.
		But for most mines it was too late: their ditches and flumes had failed, capital for adequate debris dams was difficult to raise, and their workers had moved on.
	www.cprr.org /Museum/Hydraulic_Mining (1381 words)

	Placer Mining Methods (Site not responding. Last check: 2007-11-05)
		Placer deposits are concentrations of heavy minerals, usually within loose alluvium that can easily be excavated and washed.
		Placer minerals such as gold, tin, and tungsten minerals, are of relatively high value, but the value of the placer gravel itself may be very low, often less than a dollar per cubic yard.
		The bulk of placer mining falls into three groups-- panning and sluicing / hydraulicking, and dredging.
	www.digistar.mb.ca /minsci/surf/placer.htm (104 words)

	Gold Placer Deposits (Site not responding. Last check: 2007-11-05)
		Streambed placers are the most important kind of deposit for the small-scale operator, but the gravel terraces and benches above the streams and the ancient river channels (often concealed by later deposits) are potential sources of gold.
		Other types of placers include those in outwash areas of streams where they enter other streams or lakes, those at the foot of mountainous areas or in regions where streams enter into broader valleys, or those along the ocean front where beach deposits may form by the sorting action of waves and tidal currents.
		Mining equipment may include various combinations of pumps, miniature dredges, and riffle boxes that can be built from salvage by the operator or purchased from commercial sources.
	www.earthsci.org /mindep/depfile/auplace.htm (10698 words)

	Ottawa to phase out Yukon placer mining (Site not responding. Last check: 2007-11-05)
		Placer mining involves the use water and sluices to separate gold particles and nuggets from gravel and sand.
		There are 280 licensed placer mines in the Yukon, all of them family owned and operated, the association said.
		Placer mining contributes more than $50-million a year to the Yukon economy and is the territory's second-largest industry, after tourism, the association said.
	www.freerepublic.com /focus/news/831074/posts (971 words)

	Alluvial (placer) gold diamond exploration and mining
		A cased drill sampling is guided by a refraction seismic study, to limit sampling to the most significant places, and to limit initial exploration expenses.
		Since majority of tropical alluvial (placer) deposits have a limonite-cemented layer, under which the most interesting values are, the dredge must use a cutter head or wheel.
		Many areas, where the gold or diamond alluvial (placer) deposits are found in South America, have undergone processes of rejuvenation.
	www.kanada.net /alluvial (628 words)

	Welcome to Deer Creek School's "Our Town" Project - Mining
		Placer mining was one of the earliest mining methods discovered by the miners.
		This type of mining used manual techniques and tools such as sluice boxes, pans, and rockers located near rivers and streams.
		Hydraulic mining was the most destructive type, leaving the land unusable as a result.
	www.ncgold.com /goldrushtown/mining.html (171 words)

	Placer Mining Methods (Site not responding. Last check: 2007-11-05)
		Placer means a deposit of gravel which contains particles of gold deposits.
		During the first stage of gold mining, deposits in riverbeds were worked extensively.
		Methods such as gold panning, sluicing, and use of the rocker, were common forms of placer mining during this first stage.
	collections.ic.gc.ca /cariboo/mining/placer.htm (406 words)

	Placer Mining's Contribution to the Yukon Economy - The Klondike Placer Miners' Association
		Currently, placer mining is the second largest private sector income earner and employer in the Yukon (after tourism), but the net economic impact may in fact be the largest as the Yukon tourism industry is heavily subsidized.
		BDO Dunwoody stated: “Survey results indicate that the mining industry has a significant impact on the Yukon economy.” In these dire economic times, it is clear that placer mining is extremely important to the Yukon’s economy.
		This indicates that most Yukon Placer miners have been around for a long time and are committed to the industry.” There have been claims that placer industry is a “come and go” industry; however, the data shows quite the contrary, with the number of placer operations remaining fairly consistent despite price fluctuations.
	www.kpma.ca /economics.htm (792 words)

	Mining Video Library
		Although the major focus of the speakers is placer mining technology, a number of experts discuss recovery equipment, project financing, international experiments as well as day-to-day operations.
		He expands on alternatives to mainstream mining methods and provides a brief examination of what factors especially affect the choice of a placer mining operation.
		He is the author of studies on geomorphology as guide to exploration and evaluation of placer deposits and the morphology and weather reaction of gold particles to determine transport distance and lode source type.
	www.amproductions.com /videos/mining/mine.html (1638 words)

	Prospecting for Gold in the United States
		However, most placer deposits have been thoroughly reworked at least twice--first by Chinese laborers, who arrived soon after the initial boom periods and recovered gold from the lower grade deposits and tailings left by the first miners, and later by itinerant miners during the 1930's.
		A placer deposit is a concentration of a natural material that has accumulated in unconsolidated sediments of a stream bed, beach, or residual deposit.
		Placers in Colorado have been mined in the Fairplay district in Park County, and in the Breckenridge district in Summit County.
	pubs.usgs.gov /gip/prospect2/prospectgip.html (2849 words)

	Parks Canada - Dredge No. 4 National Historic Site of Canada - History
		This was accomplished at Forty Mile in 1887 with the introduction of wood burning, a technique that entailed thawing an area of frozen ground (six-by-four feet or 1.8 x 1.2 m) with wood fires, removing the thawed gravels, and repeating the process until bedrock had been reached.
		The great attraction of shaft and drift mining, apart from steam thawing and the use of self-dumpers which were used on a small scale prior to 1900, was that it required relatively little capital.
		Unfortunately for the small operator, the extensive application of shaft and drift mining during the rush, coupled with the high-grading principle on which it was based, resulted in the rapid depletion of the rich pay gravels on which shaft and drift mining depended for success.
	www.pc.gc.ca /lhn-nhs/yt/dn4/natcul/natcul5_E.asp (1316 words)

	Idaho Mining Association : History
		Mining in Idaho has shaped the state's political boundaries, built cities, and supplied the nation with minerals necessary for today's modern lifestyle which many of us take for granted.
		The history of mining in Idaho is as colorful as the metal that first drew thousands of fortune seekers to the Gem State.
		Unlike many placer mining districts, the millions of dollars invested in Owyhee underground mines and mills would assure Silver City a long, if sometimes turbulent, future.
	www.idahomining.org /history.html (926 words)

	Welcome to Deer Creek School's "Our Town" Project - Mining - Placer Mining
		They invented new methods of mining gold which were faster and easier.
		As the dirt was washed over wooden riffles the gold was caught between the riffle bars in the cradle.
		The Sluice box was another efficient method of placer mining because more dirt could be washed in a shorter amount of time.
	www.ncgold.com /goldrushtown/placermining.html (534 words)

	placer mining on Encyclopedia.com (Site not responding. Last check: 2007-11-05)
		Federal rules threaten placer mining: exceedingly tough pollution standards could wipe out a venerable Yukon and B.C. tradition.
		Placer Dome reverses $76 million expense related to Ontario mining tax ruling.
		Placer Dome focusses on rationalizing employment, additional cost reductions for the balance of the year.
	www.encyclopedia.com /html/x/x-placermi.asp (210 words)

	www.mineweb.net \| sections \| sustainable mining Placer gets slammed in decade-old Marcopper disaster (Site not responding. Last check: 2007-11-05)
		While Placer Dome has quietly negotiated for years with Reyes and other officials concerning a settlement regarding the Marcopper tailings spill, Reyes chose to sue Placer in a Clark County state court in Las Vegas, in southern Nevada, despite the fact most mining cases are usually filed in northern Nevada courtrooms.
		Placer Dome contends that it "contained the problem, remediated the effects of the accidents, compensated those affected and worked diligently to be a positive presence on the island of Marinduque in the absence of any other party willing or able to provide the necessary work and funding."
		Placer Dome has not yet been served with the suit and could not legally comment on its contents.
	www.mineweb.net /sections/sustainable_mining/497411.htm (1029 words)

	Gold Prospecting & Gold Mining
		During much time gold has been the most attractive metal on the world, and still to this day is one the ones most fever and many developments and new ideas have appeared as a consequence of its huge value as an economic metal.
		The gold mining industry has grown considerably, and it appeared to the writer that the present would be a propitious time to bring out some guides in order to understand gold prospecting and gold mining.
		The characteristics of an ore deposit and its minerals assemblages (mineralization) determine mining methods, extraction process (recovery methods and process equipment needed), and the performance of all chemical processes involved in gold extraction.
	www.e-goldprospecting.com (507 words)

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