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Placer deposits are masses of unconsolidated and semi-consolidated clastic sediment formed by surface weathering and erosion of primary rocks that are subsequently transported by gravity, water, wind, or ice from their original source and redeposited elsewhere. ... The former are mined largely for their iron content and the latter for their ...
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Bog Iron ore was formerly mined in Europe hundreds of years ago when the large iron ore deposits had not been discovered. It consists of iron hydroxide (goethite) deposited in swamps and lakes as a product of bacterial action. ... The placer deposits usually form from primary deposits in which the ore mineral is widely disseminated and ...
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Often placer deposits are found within sedimentary rocks and can be billions of years old, for instance the Witwatersrand deposits in South Africa. 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 ...
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Residual placer deposits formed in the immediate vicinity of source rocks are usually not the most productive, although exceptions occur where veins supplying the gold were unusually rich. ... Upon weathering, such gold may be coated …
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Technically a placer deposit is the general term for a mineral deposit formed by the concentration of moving particles by gravity. Alluvial is the name for placer deposits formed by water action in a stream or river. ... heavy …
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All placer deposits have concentrated gold from its source in some kind of trap. The vast majority of the placer gold that is mined in the world is of the alluvial variety. ... Areas where there is a lot of iron can break down rapidly as the iron …
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Head iron-sand deposit, South Auckland, Geology and. Exploration of New Zealand Iron-sand Deposits, Monograph. ... Placer deposits can be formed by in situ weathering, but the majority of placer ...
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Placer deposits: These deposits are formed when heavy minerals are transported and deposited by running water or glaciers. The valuable minerals are often concentrated in stream beds or beaches, ... Iron ore: Sedimentary …
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Placer Deposit. When current waters slow down, __ __ can be formed by high density minerals. ... Disseminated Ore. Low-grade hydrothermal deposits throughout a rock body are called __ ___ deposits. Residual Ore. Bauxite is an example of a ___ ___. Banded Iron Formations. Layers of iron-rich minerals sandwiched b/w beds of silica minerals are ...
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Placer deposits, or simply "placers",are accumulations of valuable minerals concentrated in overburden, in ... Uranium is the reverse of iron: highly oxidized state is soluble. Uraninite (UO 2 ...
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Placer Gold Deposits of Arizona by Maureen G. Johnson contains an inventory of gold placer mines, prospects and deposits located within Arizona. This Bulletin is out of production by the USGS but has been Modified and Reprinted by Iron Fire Publications with expanded information. Adds WGS 84 coordinates for placer locations.
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Remote Sensing Application in Exploration of Iron Mineral Placer Deposit: Case Study of Kulonprogo's Iron Placer Deposit April 2018 DOI: 10.3997/2214-4609.201800385
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Placer mining, ancient method of using water to excavate, transport, concentrate, and recover heavy minerals from alluvial or placer deposits. Examples of deposits mined by means of this technique are the gold-bearing sands and gravel that settle out …
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Placer mining is used to recover valuable minerals from sediments in present-day river channels, beach sands, or ancient stream deposits. More than half of the world's titanium comes from …
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Mining - Placer, Streams, Alluvial: Placers are unconsolidated deposits of detrital material containing valuable minerals. The natural processes by which they form range from chemical weathering to stream, marine, and wind action. Typical minerals recovered in placers are gold, tin, platinum, diamonds, titaniferous and ferrous iron sands, gemstones (rubies, …
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4. Conditions favourable for placer deposit development 5. Factors controlling formation of placers 6. Ages of placers 7. Mineral concentration and accumulation 8. World Distribution of placer mineral deposits 9. Indian distribution 10. Conclusions Objectives: The objectives of learning this module are to understand the placer deposits by ...
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The Pea Ridge iron deposit in Missouri contains an unexploited high-grade REE resource of unknown but probably small size in breccia pipes associated with 1.48 × 10 9-year-old ... listed five separate Idaho placer deposits that together constitute a moderate-sized resource. Monazite reserves were estimated at 38,000 t in the Cascade ...
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The word "placer" was used by early Americans, and others, to designate gold-bearing deposits of stream gravel. This term is thought to have been derived from the Spanish plaza, meaning "place" or, locally, "sand bank."The Germans used the word Seife, or Erzseife, for a placer type of mineral deposit, while the British, Australians, and South Africans, among others, referred to ...
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Examples include the placer iron deposits mined in New Zealand, the Philippines, and Japan; the glass-sand and feldspar deposit mined in California; and the sand and gravel deposits that yield construction material in many parts of the world.
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There are two major types of deposit. The first, and by far the most important, is banded iron formations (BIFs), so called because they are finely layered alternations of cherty silica and an iron mineral, generally hematite, magnetite, …
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The updated models included six gold deposit types (epithermal, orogenic, Carlin-like, alkaline-related, iron oxide copper gold, and Precambrian paleoplacer), sedimentary phosphorus (± rare earth elements) deposits, and titanium-rare earth element placer deposits. These mineral deposit models are designed for assessment use and include ...
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Remote Detection of Placer Deposits and Iron-bearing Minerals using the Infrared Spectrum for the Identification of Environmental Monitoring Sites in Benguet Catchment. Thesis. May 2018;
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Sedimentary/surficial deposits: concentrations of detrital minerals or precipitates.(a) Deposits related to sedimentation (chemical and clastic deposits) Iron ore deposits (banded iron formation-BIF, and oolitic ironstones) Evaporites, phosphorites, Mn deposits, etc. Placer deposits (b) Deposits related to weathering Residual deposits (Al-laterite–bauxite, Ni …
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placer mining, ancient method of using water to excavate, transport, concentrate, and recover heavy minerals from alluvial or placer deposits. Examples of deposits mined by means of this technique are the gold-bearing sands and gravel that …
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Half or more of our gold, titanium minerals, gem diamond, zircon, and thorium comes from placers, and a considerable share of our tin, platinum, niobium and tantalum, uranium, and rare …
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Placer deposits are masses of unconsolidated and semi-consolidated clastic sediment formed by surface weathering and erosion of primary rocks that are subsequently transported by gravity, …
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The foremost is a large natural nugget from a placer deposit in California. The discovery of gold nuggets in rivers and streams of California's Sierra Nevada foothills triggered the famous "Gold Rush" of 1848 and 1849. ... The problem originated from the Iron Mountain Mine, where extensive mining activities exposed sulfide-rich ore bodies (e.g ...
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This paper examines the types of ore deposits in Nigeria. Ores of iron, tin-niobium-tantalum deposits, and precious metals in the Nigerian basement complex are predominantly associated with ... (IOA) deposits (Australia, …
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The processes leading to the formation of beach placer deposits generally begin inland and terminate at the coast, including source rocks being weathered, eroded and then transported by streams and rivers to the coast, where the sediments are deposited in a variety of coastal environments. The coastal sediments are reworked by the action of waves, tides, …
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Exploitation of the placer deposits began in 1984, producing about 24 metric tons of platinum or 40% of the resource (Shcheka et al., 2004). Average grade of the placer deposits is 1.6 g/m 3 PGEs. Drainages within the intrusive body have grades of 4 g/m 3 but are reduced to about 0.5 g/m 3 downstream over a total length of about 50 km.
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