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sand
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{{short description|A granular material composed of finely divided rock and mineral particles, from 0.063 to 2 mm diameter}}{{other uses}}{{pp|small=yes}}{{Use dmy dates|date=July 2014}}File:Libya 4608 Idehan Ubari Dunes Luca Galuzzi 2007.jpg|right|thumb|Sand dunes in the Idehan UbariIdehan UbariFile:Sand from Gobi Desert.jpg|thumb|Close-up (1×1 cm) of sand from the Gobi DesertGobi DesertSand is a granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.BOOK, Glossary of terms in soil science., 1976, Agriculture Canada, Ottawa, 978-0662015338, 35,weblink The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is calcium carbonate, for example, aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean.Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand.NEWS, Constable, Harriet, How the demand for sand is killing rivers,weblink 9 September 2017, BBC News Magazine, 3 September 2017,

Composition

File:HeavyMineralsBeachSand.jpg|thumb|Heavy minerals (dark) in a quartz beach sand (ChennaiChennaiFile:CoralPinkSandDunesSand.JPG|thumb|Sand from Coral Pink Sand Dunes State Park, Utah. These are grains of quartz with a hematitehematiteFile:PismoBeachSand.JPG|thumb|Sand from Pismo Beach, California. Components are primarily quartz, chert, igneous rockigneous rockThe exact definition of sand varies. The scientific Unified Soil Classification System used in engineering and geology corresponds to US Standard Sieves,Unified Soil Classification System and defines sand as particles with a diameter of between 0.074 and 4.75 millimeters. By another definition, in terms of particle size as used by geologists, sand particles range in diameter from 0.0625 mm (or {{Fraction|1|16}} mm) to 2 mm. An individual particle in this range size is termed a sand grain. Sand grains are between gravel (with particles ranging from 2 mm up to 64 mm by the latter system, and from 4.75 mm up to 75 mm in the former) and silt (particles smaller than 0.0625 mm down to 0.004 mm). The size specification between sand and gravel has remained constant for more than a century, but particle diameters as small as 0.02 mm were considered sand under the Albert Atterberg standard in use during the early 20th century. The grains of sand in Archimedes Sand Reckoner written around 240 BCE, were 0.02 mm in diameter. A 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A 1938 specification of the United States Department of Agriculture was 0.05 mm.Urquhart, Leonard Church, "Civil Engineering Handbook" McGraw-Hill Book Company (1959) p. 8-2 Sand feels gritty when rubbed between the fingers. Silt, by comparison, feels like flour).ISO 14688 grades sands as fine, medium, and coarse with ranges 0.063 mm to 0.2 mm to 0.63 mm to 2.0 mm. In the United States, sand is commonly divided into five sub-categories based on size: very fine sand ({{Fraction|1|16}} – {{Fraction|1|8}} mm diameter), fine sand ({{Fraction|1|8}} mm – {{Fraction|1|4}} mm), medium sand ({{Fraction|1|4}} mm – {{Fraction|1|2}} mm), coarse sand ({{Fraction|1|2}} mm – 1 mm), and very coarse sand (1 mm – 2 mm). These sizes are based on the Krumbein phi scale, where size in Φ = -log2D; D being the particle size in mm. On this scale, for sand the value of Φ varies from −1 to +4, with the divisions between sub-categories at whole numbers.File:Volcanic sand (Perissa, Santorini, Greece).jpg|thumb|Close up of black volcanic sand from Perissa, SantoriniSantoriniThe most common constituent of sand, in inland continental settings and non-tropical coastal settings, is silica (silicon dioxide, or SiO2), usually in the form of quartz, which, because of its chemical inertness and considerable hardness, is the most common mineral resistant to weathering.The composition of mineral sand is highly variable, depending on the local rock sources and conditions. The bright white sands found in tropical and subtropical coastal settings are eroded limestone and may contain coral and shell fragments in addition to other organic or organically derived fragmental material, suggesting sand formation depends on living organisms, too.Seaweed also plays a role in the formation of sand. Susanscott.net (1 March 2002). Retrieved on 24 November 2011. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, white color. Arkose is a sand or sandstone with considerable feldspar content, derived from weathering and erosion of a (usually nearby) granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite or gypsum. Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts and obsidian. Chlorite-glauconite bearing sands are typically green in color, as are sands derived from basaltic lava with a high olivine content. Many sands, especially those found extensively in Southern Europe, have iron impurities within the quartz crystals of the sand, giving a deep yellow color. Sand deposits in some areas contain garnets and other resistant minerals, including some small gemstones.

Study

File:Sand under electron microscope.jpg|thumb|An electron micrographelectron micrograph(File:Pitted sand grains Western Desert.jpg|thumb|Pitted sand grains from the Western Desert, Egypt. Pitting is a consequence of wind transportation.)The study of individual grains can reveal much historical information as to the origin and kind of transport of the grain.Krinsley, D.H., Smalley, I.J. 1972. Sand. American Scientist 60, 286-291 Quartz sand that is recently weathered from granite or gneiss quartz crystals will be angular. It is called grus in geology or sharp sand in the building trade where it is preferred for concrete, and in gardening where it is used as a soil amendment to loosen clay soils. Sand that is transported long distances by water or wind will be rounded, with characteristic abrasion patterns on the grain surface. Desert sand is typically rounded.People who collect sand as a hobby are known as arenophiles. Organisms that thrive in sandy environments are psammophiles.WEB,weblink Psammophile
access-date=27 January 2016,

Uses

{{Refimprove section|date=January 2018}}(File:Песчинки-1. Желтый строительный песок.jpg|thumb|Sand grains of yellow building sand. Microscope Lumam P-8. EPI lighting. The photo of each grain of sand is the result of multifocal stacking..)
  • Agriculture: Sandy soils are ideal for crops such as watermelons, peaches and peanuts, and their excellent drainage characteristics make them suitable for intensive dairy farming.
  • Aquaria: Sand makes a low cost aquarium base material which some believe is better than gravel for home use. It is also a necessity for saltwater reef tanks, which emulate environments composed largely of aragonite sand broken down from coral and shellfish.
  • Artificial reefs: Geotextile bagged sand can serve as the foundation for new reefs.
  • Artificial islands in the Persian Gulf.
  • Beach nourishment: Governments move sand to beaches where tides, storms or deliberate changes to the shoreline erode the original sand.WEB,weblink Importing Sand, Glass May Help Restore Beaches, 17 July 2007, NPR.org,
  • Brick: Manufacturing plants add sand to a mixture of clay and other materials for manufacturing bricks.BOOK,weblink ENVIRONMENTAL AND ENGINEERING GEOLOGY -Volume III, Yong, Syed E. Hasan, Benedetto De Vivo, Bernhard Grasemann, Kurt Stüwe, Jan Lastovicka, Syed M. Hasan, Chen, 2011-12-05, EOLSS Publications, 9781848263574, en,
  • Cob: Coarse sand makes up as much as 75% of cob.
  • Concrete: Sand is often a principal component of this critical construction material.
  • Glass: Sand rich in silica is the principal component in common glasses.
  • Hydraulic fracturing: A drilling technique for natural gas, which uses rounded silica sand as a "proppant", a material to hold open cracks that are caused by the hydraulic fracturing process.
  • Landscaping: Sand makes small hills and slopes (golf courses would be an example).
  • Mortar: Sand is mixed with masonry cement or Portland cement and lime to be used in masonry construction.
  • Paint: Mixing sand with paint produces a textured finish for walls and ceilings or non-slip floor surfaces.
  • Railroads: Engine drivers and rail transit operators use sand to improve the traction of wheels on the rails.
  • Recreation: Playing with sand is a favorite beach time activity. One of the most beloved uses of sand is to make sometimes intricate, sometimes simple structures known as sand castles. Such structures are well known for their impermanence. Sand is also used in children's play. Special play areas enclosing a significant area of sand, known as sandboxes, are common on many public playgrounds, and even at some single family homes. Sand dunes are also popular among climbers, motorcyclists and beach buggy drivers.
  • Roads: Sand improves traction (and thus traffic safety) in icy or snowy conditions.
  • Sand animation: Performance artists draw images in sand. Makers of animated films use the same term to describe their use of sand on frontlit or backlit glass.
  • Sand casting: Casters moisten or oil molding sand, also known as foundry sand and then shape it into molds into which they pour molten material. This type of sand must be able to withstand high temperatures and pressure, allow gases to escape, have a uniform, small grain size and be non-reactive with metals.
  • Sand castles: Shaping sand into castles or other miniature buildings is a popular beach activity.
  • Sandbags: These protect against floods and gunfire. The inexpensive bags are easy to transport when empty, and unskilled volunteers can quickly fill them with local sand in emergencies.
  • Sandblasting: Graded sand serves as an abrasive in cleaning, preparing, and polishing.
  • Thermal weapon: While not in widespread use anymore, sand used to be heated and poured on invading troops in the classical and medieval time periods.
  • Water filtration: Media filters use sand for filtering water.
  • Wuḍūʾ: the Islamic procedure for washing parts of the body.
  • Zoanthid "skeletons": Animals in this order of marine benthic cnidarians related to corals and sea anemones, incorporate sand into their mesoglea for structural strength, which they need because they lack a true skeleton.

Resources and environmental concerns

Only some sands are suitable for the construction industry, for example for making concrete. Because of the growth of population and of cities and the consequent construction activity there is a huge demand for these special kinds of sand, and natural sources are running low. In 2012 French director Denis Delestrac made a documentary called "Sand Wars" about the impact of the lack of construction sand. It shows the ecological and economic effects of both legal and illegal trade in construction sand.See Sand Wars teaser here.JOURNAL, The story of climate change gets star treatment, New Scientist, 26 April 2014, 28–9,weblink Simon Ings, Strände in Gefahr? Arte Future, last updated 23 April 2014To retrieve the sand, the method of hydraulic dredging is used. This works by pumping the top few meters of sand out of the water and filling it into a boat, which is then transported back to land for processing. Unfortunately, all marine life mixed in with the extracted sand is killed and the ecosystem can continue to suffer for years after the mining is complete. Not only does this affect marine life, but also the local fishing industries because of the loss of life, and communities living close to the water's edge. When sand is taken out of the water it increases the risk of landslides, which can lead to loss of agricultural land and/or damage to dwellings.JOURNAL, Kim, Tae Goun, September 14, 2007, The economic costs to fisheries because of marine sand mining in Ongjin Korea: Concepts, methods, and illustrative results,weblink ScienceDirect, Elsevier, Sand's many uses require a significant dredging industry, raising environmental concerns over fish depletion, landslides, and flooding.NEWS, Torres, Aurora, etal, The world is facing a global sand crisis,weblink 9 September 2017, The Conversation, 8 September 2017, Countries such as China, Indonesia, Malaysia and Cambodia ban sand exports, citing these issues as a major factor.NEWS,weblink The hourglass effect, 8 October 2009, 14 October 2009, The Economist, It is estimated that the annual consumption of sand and gravel is 40 billion tons and sand is a US$70 billion global industry.NEWS, Beiser, Vince, The Deadly Global War for Sand,weblink 26 March 2015, Wired, 26 March 2015, The global demand for sand in 2017 was 9.55 billion tons as part of a $99.5 billion industry.WEB,weblink As ice melts, Greenland could become big sand exporter: study, www.reuters.com, Alister, Doyle, February 11, 2019, February 12, 2019,

Hazards

While sand is generally non-toxic, sand-using activities such as sandblasting require precautions. Bags of silica sand used for sandblasting now carry labels warning the user to wear respiratory protection to avoid breathing the resulting fine silica dust. Safety data sheets for silica sand state that "excessive inhalation of crystalline silica is a serious health concern".Silica sand MSDS {{webarchive|url=https://web.archive.org/web/20060311043051weblink |date=11 March 2006 }}. Simplot (13 March 2011). Retrieved on 24 November 2011.In areas of high pore water pressure, sand and salt water can form quicksand, which is a colloid hydrogel that behaves like a liquid. Quicksand produces a considerable barrier to escape for creatures caught within, who often die from exposure (not from submersion) as a result.

Manufactured sand

Manufactured sand (M sand) is sand made from rock by artificial processes, usually for construction purposes in cement or concrete. It differs from river sand by being more angular, and has somewhat different properties.JOURNAL, 5456819, 2016, Pilegis, M., An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete, Materials, 9, 6, 440, Gardner, D., Lark, R., 28773560, 10.3390/ma9060440,

See also

{{Div col}}
  • {{annotated link|Aggregate (geology)}}
  • {{annotated link|Beach}}
  • {{annotated link|Construction aggregate}}
  • {{annotated link|Desert sand (color)}}
  • {{annotated link|Dry quicksand}}
  • {{annotated link|Energetically modified cement}} (EMC)
  • {{annotated link|Heavy mineral sands ore deposits}}
  • {{annotated link|Oil sands}}
  • {{annotated link|Particle size}}
  • {{annotated link|Quicksand}}
  • {{annotated link|Revolving rivers}}
  • {{annotated link|Sand island}}
  • {{annotated link|Sand mining}}
  • {{annotated link|Sand rat}}
  • {{annotated link|Sandstone}}
  • {{annotated link|Dust storm|Sandstorm}}
  • {{annotated link|Sand theft}}
  • {{annotated link|Singing sand}}
  • {{annotated link|White Sands National Monument}}
{{div col end}}

References

{{reflist|30em}}

External links

{{wiktionary}}
  • weblink" title="web.archive.org/web/20091201183346weblink">Beach Sand: What It Is, Where It Comes From and How It Gets Here - Beaufort County Library
  • NSRW, Sand,


Sand Mining Side Effects
{{Geotechnical engineering|state=collapsed}}{{coastal geography}}{{Authority control}}


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