Sand is an example of a class of materials called granular matter. Sand is a naturally occurring, finely divided rock (geology), comprising particles or granules ranging in size from 0.063 to 2 mm. An individual particle in this range size is termed a sand grain. The next smaller size class in geology is silt: particles below 0.063 mm down to 0.004 mm in size. The next larger size class above sand is gravel, with particles ranging up to 64 mm (see grain size for standards in use).
The most common constituent of sand in inland continental settings and non-tropical coastal settings, is silica (silicon dioxide), usually in the form of quartz because of the considerable hardness of this mineral. However, the composition of sand varies according to local rock sources and conditions. The bright coral sand found in tropical and subtropical coastal settings is ground-up limestone. Arkose is a sand or sandstone with considerable feldspar content which is derived from the weathering and erosion of a usually nearby granite. Some locations have sands that contain magnetite, chlorite group, glauconite, or gypsum. Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts. The chlorite-glauconite bearing sands are typically green in color, as are sands derived from basalts (lavas) with a high olivine content. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, white color. Sand deposits in some areas contain garnets and other resistant minerals, including some small gemstones.
Sand is transported by wind or water and deposited in the form of beaches, dunes, bar (landform), bar (landform), and the like. In a desert, sand is a dominant constituent of the soil.
The study of sand is called arenology.
==Uses of sand==
Sand is often a principal component of the aggregate used in the preparation of concrete. Sand manufactured at rock crusher plants for use as an aggregate is called ''mansand''. Graded sand is used as an abrasive in sandblasting and is also used in media filters for filtering water.
Sandy soils are ideal for certain crops such as watermelons and peanuts and are often preferred for intensive dairy farming because of their excellent drainage characteristics.
Sand bags are used for protection against floods and gun fire. They can be easily transported when empty, and filled with local sand.
People, especially child, love to play with sand on a beach or in a sandbox. See sand art and play for details.
==Hazards of sand==
Bags of sand now typically 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 sought damages after they developed silicosis, a lung disease caused by inhalation of fine silica particles.
People have been severely injured and even killed after digging sand "caves" in large dunes, sandhills, or even on beaches when the cave or tunnel collapsed upon them.
==See also==
*Quicksand
*Dry quicksand
*Grain size
*Sandstone
*Windstorm
*Singing sand
*White Sands National MonumentSedimentologyGranular materialsSedimentsfa:شن
Sand
I deleted the somewhat silly entry "People, especially children, love to play with sand on a beach or in a sandbox. On beaches they make a mountain, a pit, canals, tunnels, a statue, a building (such as a sand castle), etc." as being not very encyclopedic. Would anyone interested in mountains and buildings (links in sentence) really want to know anything about this (beach play) aspect or vice versa? After all, there is probably no limit to the images one could make out of sand on a beach. But this is a collaborative effort, and one man's silliness is probably another's encyclopedia. I'm not hard-nosed. I sugggest delete, but leave that to others to decide / User:Marshman 23:15, 6 Aug 2003 (UTC)
:Playing is one of the common applications of sand and worth mentioning. Playing is not silly, no need to declare it a taboo subject. - User:Patrick 23:43, 6 Aug 2003 (UTC)
:I've been giving it some thought and a sub-heading of uses of sand could be made with this one aspect. Others could be manufacture of concrete, beach replenishment. I'm confident that as the encyclopedia grows, items will sort themselves into proper articles / User:Marshman 04:24, 7 Aug 2003 (UTC)
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Grain size says sand is in the range 0.063 - 2 mm. - User:Patrick 07:57, 14 Aug 2003 (UTC)
:I see the disagreement. Let me check into it further. Thanks - User:Marshman 08:19, 14 Aug 2003 (UTC)
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I'm not sure that you can grow watermelons in the sand itself. Maybe this part could be moved to something like sandy soils? --User:Nk 16:17, 6 Oct 2004 (UTC)
:I think you are right. I will move down to the subsection "uses", but eventually, a sandy soil could be developed. Right now, the soil article is in its infancy - User:Marshman 17:01, 6 Oct 2004 (UTC)
== Formation of sand ==
Could someone describe the process of sand formation?
Reading http://www.susanscott.net/Oceanwatch2002/mar1-02.html this article, I found a connection to foraminifera - could some please elaborate on this? - PvL 5/5/2005
:Yes. Good idea. The article needs this aspect. I'll see what I can contribute. - User:Marshman 01:02, 5 May 2005 (UTC)
== Help me! ==
Does anyone know how purple/violet/blue sand is formed on otherwise normal yellow-sand beaches?
I have been digging the net for one hour and not a clue ...
:C'mon. You need to provide a bit more information than that. Where is this purple and? Who said it is purple? There are probably no blue sands, but maybe something close. Your question is so vague I'm going to assume (ass of you and me) you are joking unless you can define a few terms like "normal yellow". - User:Marshman 04:48, 6 May 2005 (UTC)
Sorry Marshie, I swear that every perceptive individuals who walked the beaches of the Baltic and the Black Sea will know the difference between yellow and violet sand (I used the word "purple" because it is more often seen on the net). It is too obvious to miss. In other words, the definition of the problem is sufficient for those "in the know"
:Yourquestion seems to be saying that all the beaches in thisarea are yellow (normal yellow). but in some places this sand is replaced by or covered by or mixed with violet sand; is that right? - User:Marshman 17:40, 6 May 2005 (UTC)
::apparently it turns purple in british columbia at least. [http://www.hat.net/album/north_america/canada/british_columbia/vancouver/020907_spanish_bank/detail012.htm] California too. [http://www.nikhilk.net/Photo.aspx?id=70] I know nothing about this and i've never seen it before, but it looks interesting. User:Ungtss 21:53, 6 May 2005 (UTC)
:::apparently volcanic sand can be purple. is that a possible cause? User:Ungtss 22:24, 6 May 2005 (UTC)
I think the example pictures are easy to explain. The beach photos from [http://www.nikhilk.net/Photo.aspx?id=70 California] are of a dark sand beach. The term "normal yellow" (which has not been defined here) does not apply in any sense. The sand here is the result of the breakdown of the local rocks, shown in the photos. The beach is a dark color, perhaps mostly black, but there may be a red chert or some similar mineral also being contributed. The combinastion of the reddish or red-brown grains and black grains looks purple under the right conditions. The photo from [http://www.hat.net/album/north_america/canada/british_columbia/vancouver/020907_spanish_bank/detail012.htm British Columbia] is largely an artifact of the film and lighting conditions. The photo is of a light colored sand taken near sunset (sunrise?) when the sun's rays are filtered through atmospheric conditions that give a purplish coloration to shadows, and in this case, reflective surfaces too. Neither example is really one of purple or violet grains, but of the way the sand looks to the camera (and perhaps the eye): purple, yes - User:Marshman 02:25, 7 May 2005 (UTC)
In some places, the two kinds of sand mix. The purple sands seems to be washed out from some sediment in the dunes, but then it seems to be laid out in layers on a freshly formed beach (as if lighter than the yellow sand; depositing slowly). Some old fisherman mentioned "potassium permanganate", but that can be completely wrong. Sometimes, if you scratch the purple layer with a foot, it shows to be just 1-3 mm thick exposing wet yellow sand underneath.
:Good observations. There is no doubt that sands from different sources get sorted differently by the waves. Think of the wave action as a very good sorting/sieving system. Each wave picks up the grains and then deposits them according to the energies applied to different masses (size and density). I've seen this many times where calcareous (white) sands are mixed with volcanic (dark) sands. The result is not an even pepper appearance, but sometimes dark under the light, or dark in rivulets across the light. Potassium permanganate is too soluble and too soft as a crystal to be involved in a sand. - User:Marshman 04:35, 10 May 2005 (UTC)
Dear Marshman, after reading your reasoning, it seems this sand must come from some older dune deposits. There must be some local people, fishermen, oceanographers, forest inspectors or agriculture experts who will know. While still on vacation, I will do my best to inquire and perhaps zero in on the answer. Milan
:Yes, another possibility: that at higher tides the source of the sand is slightly different, produicing in some seasons a layered effect. - User:Marshman 17:37, 10 May 2005 (UTC)
I am currently at the Baltic coast. Baltic is tideless (shallow). On close inspection, it is very clear that the sand can take all colors from yellow through pink to purplish via violet to black. The culprits are tiny black grains of some substance that looks like 0.1-0.3 mm graphite flakes. The bigger the dose of the grains, the darker the sand. The grains tend to desposit together, hence the clear yellow-violet separation. I have a snapshot of a clay cliff that seems to "leak" those grains, but I have no place to upload it for you in case you were interested to have a peek (the cliff is rather grim and ugly and it is said to host remnants of WW2, mostly aerial bombs, yet the grains producing violet color are not rust, and definitely not KMnO4 -- although a picture of KMnO4 at Wikipedia looks very similar to those flakes, which are definitely not soluble/reactive). The flakes must have some flat well-polished surfaces because they seem to beautifully reflect light when set at the right angle. Probably a physicist could explain how black&shiny admixture combined with mostly transparent grains produces those beautiful color effects. mc.