Sand
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Jakdaripr
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cleaning up
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[[Image:Third beach sand.jpg|thumb|right|Close-up of sand from a beach in Vancouver, showing a surface area of (approximately) between 1-2 square centimetres.]]
[[Image:HeavyMineralsBeachSand.jpg|right|thumb|Heavy minerals (dark) in a quartz beach sand ([[Chennai]], India).]]
'''Sand''' is a naturally occurring [[granular material]] composed of finely divided [[rock (geology)|rock]] and [[mineral]] particles.
As the term is used by [[geologists]], sand particles range in [[diameter]] from 0.0625 (or {{Fraction|1|16}} mm) to 2 [[millimeter]]s. An individual particle in this range size is termed a '''sand grain'''. The next smaller size class in [[geology]] is [[silt]]: particles smaller than 0.0625 mm down to 0.004 mm in diameter. The next larger size class above sand is [[gravel]], with particles ranging from 2 mm up to 64 mm (see [[Particle size (grain size)|particle size]] for standards in use). 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 USA, sand is commonly divided into five sub-categories based on size: very fine sand (1/16 - 1/8 mm diameter), fine sand (1/8 mm - 1/4 mm), medium sand (1/4 mm - 1/2 mm), coarse sand (1/2 mm - 1 mm), and very coarse sand (1 mm - 2 mm). These sizes are based on the [[Particle size (grain size)|Φ sediment size scale]], where size in Φ = -log base 2 of 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.
==Constituents of Sand==
[[Image:Drill_cuttings_-_Annotated_-_2006.jpg|thumb|left|Sample of [[drill cuttings]] including sand, while drilling an [[oil well]] in [[Louisiana]] at approximately 9000 ft. Sand grain = 2mm. in dia.]]
[[Image:Volcanic sand (Perissa, Santorini, Greece).jpg|thumb|Close up of black volcanic sand from Perissa, in [[Santorini]], Greece]] The most common constituent of sand, in inland continental settings and non-[[tropical]] coastal settings, is [[silica]] (silicon dioxide, or SiO<sub>2</sub>), usually in the form of [[quartz]], which, because of its chemical inertness and considerable hardness, is resistant to [[weathering]].
The composition of sand is highly variable, depending on the local rock sources and conditions. The bright [[coral sand|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.<ref>[http://www.susanscott.net/Oceanwatch2002/mar1-02.html Seaweed also plays a role in the formation of sand<!-- Bot generated title -->]</ref> 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 the [[weathering]] and [[erosion]] of a (usually nearby) [[granite]]. Some sands contain [[magnetite]], [[chlorite group|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 basalt ([[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 colour. Sand deposits in some areas contain [[garnet]]s and other resistant minerals, including some small [[gemstone]]s.
Sand is transported by wind and water and deposited in the form of [[beach]]es, [[dune]]s, [[bar (landform)|sand spits]], [[bar (landform)|sand bars]] and related features.
==Study of Sand==
[[Image:Sand under electron microscope.jpg|thumb|left|An electron micrograph showing grains of sand]]
[[Image:N503287791 270717 2945.jpg|thumb|right|Beach Sand of the Beaches of the [[Red Sea]] in [[Egypt]]]]
Study of individual grains can reveal much historical information as to the origin and kind of transport of the grain. Quartz sand that is recently weathered from [[granite]] or [[gneiss]] quartz crystals will be angular. It is called ''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 [[arenophile]]s or psammophiles.
==Uses of Sand==
[[Image:Sanden ICE3.jpg|thumb|At 300 km/h, an [[Siemens Velaro|ICE 3]] (DB class 403) releases sand from several bogies to the rails.]]
[[Image:Sand sorting tower.jpg|thumb|right|Sand sorting tower at a gravel extraction pit.]]
*Sand is often a principal component of [[concrete]].
*[[Molding sand]], also known as [[foundry]] sand, is moistened or oiled and then shaped into molds for [[sand casting]]. 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.
*It is the principal component in [[glass]] production.
*Graded sand is used as an [[abrasive]] in [[sandblasting]] and is also used in [[media filter]]s for filtering [[water]].
*[[Brick]] [[manufacturing plant]]s use sand as an additive with a mixture of [[clay]] and other materials for manufacturing bricks.
*Sand is sometimes mixed with [[paint]] to create a [[Texture (crystalline)|texture]]d finish for walls and ceilings or a non-slip floor surface.
*Sandy [[soil]]s are ideal for certain crops such as [[watermelon]]s, [[peach]]es, and [[peanut]]s and are often preferred for intensive [[dairy farming]] because of their excellent drainage characteristics.
*Sand is used in [[Landscape engineering|landscaping]], it is added to make small hills and slopes (for example, constructing [[golf]] courses).
*[[Beach nourishment]] - transportation to popular [[beach]]es where seasonal tides or artificial changes to the shoreline cause the original sand to flow out to sea.<ref>[http://www.npr.org/templates/story/story.php?storyId=12026379 Importing Sand, Glass May Help Restore Beaches : NPR<!-- Bo title -->]</ref>
*[[Sandbag]]s are used for protection against [[flood]]s and [[gun]] fire. They can be easily transported when empty, then filled with local sand.
*[[Sand castle]] building is a popular activity. There are competitive sand castle building competitions (See [[sand art and play]]).
*[[Sand animation]] is a type of [[performance art]] and a technique for creating [[animation|animated film]]s.
*[[Aquarium|Aquaria]] are often lined with sand instead of gravel. This is a low cost alternative which some believe is better than gravel.
*[[Rail transport|Railroads]] use sand to improve the traction of wheels on the rails.
*[[Weights]] can use sand in pulley and gear systems as weights.
==Hazards==
[[Image:Suesswasserstachelroche.jpg|thumb|A [[stingray]] about to bury itself in sand]] [[Image:Sandstorm.jpg|thumb|left|Sandstorm in Iraq.]]While sand is generally harmless, one must take care with some activities involving sand such as [[sandblasting]]. Bags of silica sand used for sandblasting now carry labels warning the user to wear respiratory protection and avoid breathing the fine silica dust. There have been a number of lawsuits in recent years where workers have developed [[silicosis]], a [[lung disease]] caused by inhalation of fine silica particles over long periods of time. [[Material safety data sheet]]s (MSDS) for silica sand state that "excessive inhalation of crystalline silica is a serious health concern".[http://www.simplot.com/industrial/silica/silica_msds.cfm]
In areas of high [[pore water pressure]] sand can partially liquefy to form [[quicksand]]. Quicksand, once dried, produces a considerable barrier to escape for creatures caught within, who often die from exposure as a result.
==See as well==
{{wiktionary}}
{{commonscat|Sand}}
*[[Dry quicksand]]
*[[Particle size]]
*[[Quicksand]]
*[[Sand Rat]]
*[[Sandstone]]
*[[Dust storm|Sandstorm]]
*[[Sand island]]
*[[Singing sand]]
*[[Tar sands]]
*[[White Sands National Monument]]
*[[Heavy mineral sands ore deposits]]
==References==
{{refimprove|date=May 2007}}
{{reflist}}
==External links==
* [http://www.bcgov.net/bftlib/beachsan.htm ''Beach Sand: What It Is, Where It Comes From and How It Gets Here'']-- Beaufort County Library
{{Geotechnical engineering|state=collapsed}}
[[Category:Granular materials]]
[[Category:Soil]]
[[Category:Sediments]]
[[Category:Sedimentology]]
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