Sand is a naturally occurring 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.
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 artificially, such as by crushing shells or coral. 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. Thirdly, artificial sands (residuals from ore processing) are becoming increasingly popular as a construction material because they are less expensive than natural sands and offer improved strength and durability properties compared with natural sands. Sands are used extensively in concrete as aggregate for mortar and plaster; as fill; Asphalt concrete; Landscaping (such as creating beds for plants); Backfill around pipe trenches; In golf course bunkers etc…
There are many different types ofsand: eolian sand– formed from wind-blown deposits; fluvialor alluvial sand–formed from river deltas or floodplains glacial outwashsand– eroded deposits at glaciers’ termini marineand estuarine sediment – deposited along coastlines playaor sabkhasand– evaporite minerals that precipitate out in hot desert environments polycrystallinesilica – found near some volcanic regions Quartzoseand – found near metamorphic belts rich insilica weathering products – develop under warm wet climates
Each typeofsand has unique physical characteristics that can be used to help identify it: Grain size – Thisis measured using either a setof sieves with progressively smaller mesh sizesorby passingthe sample through successively smaller sieves Particle shape – Angularityrefers to how sharp each grain is while roundnessis a measureof how sphericaleach grain appears Color – Thiscan vary depending on what minerals make up the grains Optical properties – Birefringencecan be seen when looking at certaingrains under polarized light X-ray diffractionpatterns can be usedto identify what mineralsare present Weatheringproducts will often show upas stainson otherwise clean grains Magnetic properties may also provide clues abouta sample’s origins Some samplesmay exhibit luminescencewhen exposedto ultravioletlight
Sedimentologistsuse these physical characteristics toget an ideaabout howthe sedimentswere depositedandwhat processeshave affected them since their formation Differenttypesof rockswillweatheratdifferentrates so knowingwhat kindsof rockswerein an area to beginwith can helpto interpretchanges that havehappened since deposition When tryingto piece togetherancientenvironmentsit becomesvery importanttounderstand modernprocessessothat you don’tmisinterpretwhat you’re seeing Physicalcharacteristicsalone howevercannot giveus allofthe information we needabout ancientdepositionalenvironments To get agoodideaabout howsedimentsweredepositedwe must alsoconsidertheir chemicalcomposition