What is placer deposit? How placer deposits are formed
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⚒️ Placer deposit ⚒️
💠 Placer deposit, natural concentration of heavy minerals caused by the effect of gravity on moving particles.
💠 When heavy, stable minerals are freed from their matrix by weathering processes, they are slowly washed downslope into streams that quickly winnow the lighter matrix.
💠Thus the heavy minerals become concentrated in stream, beach, and lag (residual) gravels and constitute workable ore deposits.
💠 Minerals that form placer deposits have high specific gravity, are chemically resistant to weathering, and are durable; such minerals include gold, platinum, cassiterite, magnetite, chromite, ilmenite, rutile, native copper, zircon, monazite, and various gemstones.
💠 There are several varieties of placer deposits: stream, or alluvial, placers; eluvial placers; beach placers; and eolian placers.
💠 Stream placers, by far the most important, have yielded the most placer gold, cassiterite, platinum, and gemstones.
💠 Primitive mining probably began with such deposits, and their ease of mining and sometime great richness have made them the cause of some of the world’s greatest gold and diamond “rushes.” Stream placers depend on swiftly flowing water for their concentration.
💠 Because the ability to transport solid material varies approximately as the square of the velocity, the flow rate plays an important part; thus, where the velocity decreases, heavy minerals are deposited much more quickly than the light ones.
💠 Examples of stream placers include the rich gold deposits of Alaska and the Klondike, the platinum placers of the Urals, the tin (cassiterite) deposits of Malaysia, Thailand, and Indonesia, and the diamond placers of Congo (Kinshasa) and Angola.
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A placer deposit is a concentration of naturally occurring valuable minerals, such as gold, diamonds, or titanium, that have been deposited in a sedimentary environment, such as a riverbed, beach, or alluvial fan. These deposits are formed when the minerals are separated from the surrounding rock and sediment by natural processes, such as weathering, erosion, and transport by water, wind, or ice.
Placer deposits are typically found in areas where there is a source of mineral-rich rocks, such as a mountain range or an old volcanic field. As the minerals are weathered and eroded from the rocks, they are carried by water, wind, or ice and deposited in a sedimentary environment, where they accumulate over time. Placer deposits are often found in areas with a high level of water flow, such as along rivers or streams, and they can also be found in areas with a high level of wind activity, such as along beaches or in sand dunes.
Placer deposits are often mined using surface mining techniques, such as panning, sluicing, or dredging, which involve separating the valuable minerals from the surrounding sediment using water or mechanical methods. These deposits are typically less expensive to mine than other types of ore deposits, as they do not require the expensive and complex underground mining techniques that are used to extract minerals from veins or lodes. Placer deposits are an important source of a variety of minerals, including gold, diamonds, titanium, and other precious and industrial minerals
⚒️ Placer deposit ⚒️
💠 Placer deposit, natural concentration of heavy minerals caused by the effect of gravity on moving particles.
💠 When heavy, stable minerals are freed from their matrix by weathering processes, they are slowly washed downslope into streams that quickly winnow the lighter matrix.
💠Thus the heavy minerals become concentrated in stream, beach, and lag (residual) gravels and constitute workable ore deposits.
💠 Minerals that form placer deposits have high specific gravity, are chemically resistant to weathering, and are durable; such minerals include gold, platinum, cassiterite, magnetite, chromite, ilmenite, rutile, native copper, zircon, monazite, and various gemstones.
💠 There are several varieties of placer deposits: stream, or alluvial, placers; eluvial placers; beach placers; and eolian placers.
💠 Stream placers, by far the most important, have yielded the most placer gold, cassiterite, platinum, and gemstones.
💠 Primitive mining probably began with such deposits, and their ease of mining and sometime great richness have made them the cause of some of the world’s greatest gold and diamond “rushes.” Stream placers depend on swiftly flowing water for their concentration.
💠 Because the ability to transport solid material varies approximately as the square of the velocity, the flow rate plays an important part; thus, where the velocity decreases, heavy minerals are deposited much more quickly than the light ones.
💠 Examples of stream placers include the rich gold deposits of Alaska and the Klondike, the platinum placers of the Urals, the tin (cassiterite) deposits of Malaysia, Thailand, and Indonesia, and the diamond placers of Congo (Kinshasa) and Angola.