"හුණු ගල්" හි සංශෝධන අතර වෙනස්කම්
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ඉංග්‍රීසි අන්තර්ගතය ඉවත් කෙරිණි |
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[[File:La Zaplaz, Piatra Craiului.jpg|thumb|200px|right|La Zaplaz formations in the [[Piatra Craiului Mountains]], [[Romania]].]] |
[[File:La Zaplaz, Piatra Craiului.jpg|thumb|200px|right|La Zaplaz formations in the [[Piatra Craiului Mountains]], [[Romania]].]] |
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අනෙකුත් බොහෝ අවසාදිත පාෂාණ මෙන්ම, හුණු ගල් බොහොමයක් කණිකා වලින් සැදුම් ලත් වේ. හුණු ගල්හි ඇති බොහෝ කණිකා [[කොරල්]] හෝ [[ෆොරමිනිෆරා]] වැනි මුහුදු ජීවීන්ගේ අස්ථි කොටස් වේ. හුණු ගල් වල අඩංගු වන අනෙකුත් කාබනේට කණිකා වනුයේ [[ooids]], [[peloids]], [[intraclasts]], සහ [[extraclasts]] වේ. මෙම ජීවීන් ඇරගනයිට් හෝ කැල්සයිට් වලින් සැදුම් ලත් කවච ශ්‍රාවය කරන අතර, එම ජීවීන්ගේ මරණයෙන් පසු මෙම කවච පසෙකලනු ලැබේ. |
අනෙකුත් බොහෝ අවසාදිත පාෂාණ මෙන්ම, හුණු ගල් බොහොමයක් කණිකා වලින් සැදුම් ලත් වේ. හුණු ගල්හි ඇති බොහෝ කණිකා [[කොරල්]] හෝ [[ෆොරමිනිෆරා]] වැනි මුහුදු ජීවීන්ගේ අස්ථි කොටස් වේ. හුණු ගල් වල අඩංගු වන අනෙකුත් කාබනේට කණිකා වනුයේ [[ooids]], [[peloids]], [[intraclasts]], සහ [[extraclasts]] වේ. මෙම ජීවීන් ඇරගනයිට් හෝ කැල්සයිට් වලින් සැදුම් ලත් කවච ශ්‍රාවය කරන අතර, එම ජීවීන්ගේ මරණයෙන් පසු මෙම කවච පසෙකලනු ලැබේ. |
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Limestone often contains variable amounts of [[silica]] in the form of [[chert]] ([[chalcedony]], [[flint]], [[jasper]], etc.) or siliceous skeletal fragment (sponge spicules, [[diatoms]], [[radiolarians]]), and varying amounts of [[clay]], [[silt]] and [[sand]] ([[Earth|terrestrial]] [[detritus]]) carried in by rivers. |
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Some limestones do not consist of grains at all, and are formed completely by the chemical [[Precipitation (chemistry)|precipitation]] of [[calcite]] or [[aragonite]], i.e. [[travertine]]. Secondary calcite may be deposited by [[Supersaturation|supersaturated]] [[Meteorology|meteoric]] waters ([[groundwater]] that [[Precipitation (chemistry)|precipitates]] the material in caves). This produces [[speleothem]]s, such as [[stalagmite]]s and [[stalactite]]s. Another form taken by calcite is oolitic limestone, which can be recognized by its granular (oolite) appearance. |
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The primary source of the calcite in limestone is most commonly [[marine biology|marine organisms]]. Some of these organisms can construct mounds of rock known as reefs, building upon past generations. Below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters (see [[lysocline]]). Limestones may also form in both [[Lake|lacustrine]] and [[evaporite]] [[Sedimentary depositional environment|depositional environments]].<ref>{{cite journal |last=Trewin |first=N. H. |last2=Davidson |first2=R. G. |year=1999 |title=Lake-level changes, sedimentation and faunas in a Middle Devonian basin-margin fish bed |journal=[[Journal of the Geological Society]] |volume=156 |issue=3 |pages=535ֵ48 |doi=10.1144/gsjgs.156.3.0535 }}</ref><ref>[http://www.glossary.oilfield.slb.com/Display.cfm?Term=evaporite Oilfield Glossary: Term 'evaporite']. Glossary.oilfield.slb.com. Retrieved on 2011-11-25.</ref> |
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Calcite can be either [[solvation|dissolved]] or [[precipitate]]d by groundwater, depending on several factors, including the water temperature, [[acidity|pH]], and dissolved [[ion]] concentrations. Calcite exhibits an unusual characteristic called [[Solubility#Temperature|retrograde solubility]], in which it becomes less soluble in water as the temperature increases. |
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Because of impurities, such as [[clay]], sand, organic remains, [[iron oxide]] and other materials, many limestones exhibit different colors, especially on [[Weathering|weathered]] surfaces. |
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Limestone may be crystalline, [[Clastic rock|clastic]], granular, or massive, depending on the method of formation. Crystals of calcite, [[quartz]], [[dolomite]] or [[barite]] may line small cavities in the rock. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. |
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[[Travertine]] is a banded, compact variety of limestone formed along streams, particularly where there are waterfalls, and around hot or cold springs. Calcium carbonate is deposited where evaporation of the water leaves a solution supersaturated with the chemical constituents of calcite. [[Tufa]], a porous or cellular variety of travertine, is found near waterfalls. [[Coquina]] is a poorly consolidated limestone composed of pieces of [[coral]] or [[Animal shell|shell]]s. |
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During regional [[metamorphism]] that occurs during the mountain building process ([[orogeny]]), limestone recrystallizes into [[marble]]. |
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Limestone is a [[parent material]] of [[Mollisol]] soil group. |
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==Classification== |
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Two major classification schemes, the Folk and the Dunham, are used for identifying limestone and carbonate rocks. |
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===Folk classification=== |
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{{main|Folk classification}} |
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Robert L. Folk developed a classification system that places primary emphasis on the detailed composition of grains and interstitial material in carbonate rocks. Based on composition, there are three main components: allochems (grains), matrix (mostly micrite), and cement (sparite). The Folk system uses two-part names; the first refers to the grains and the second is the root. It is helpful to have a petrographic microscope when using the Folk scheme, because it is easier to determine the components present in each sample.<ref name="Folk">{{cite book |last=Folk |first=R. L. |year=1974 |title=Petrology of Sedimentary Rocks |publisher=Hemphill |location=Austin, Texas |isbn= }}</ref> |
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===Dunham classification=== |
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{{main|Dunham classification}} |
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The Dunham scheme focuses on depositional textures. Each name is based upon the texture of the grains that make up the limestone. Robert J. Dunham published his system for limestone in 1962; it focuses on the depositional fabric of carbonate rocks. Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles. Dunham names are essentially for rock families. His efforts deal with the question of whether or not the grains were originally in mutual contact, and therefore self-supporting, or whether the rock is characterized by the presence of frame builders and algal mats. Unlike the Folk scheme, Dunham deals with the original porosity of the rock. The Dunham scheme is more useful for hand samples because it is based on texture, not the grains in the sample.<ref name="Dunham">{{cite book |last=Dunham |first=R. J. |year=1962 |chapter=Classification of carbonate rocks according to depositional textures |editor-last=Ham |editor-first=W. E. |title=Classification of carbonate rocks |series=Am. Assoc. Petroleum Geologists Mem. |volume=1 |pages=108ֱ21 }}</ref> |
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== Limestone landscape == |
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{{Main|Karst topography}} |
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[[File:Maczuga Herkulesa (background Castle Pieskowa Skala).jpg|thumb|upright|left|''[[Maczuga Herkulesa|The Cudgel of Hercules]]'', a tall limestone rock ([[Pieskowa Skala|Pieskowa Skala Castle]] in the background)]] |
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Limestone makes up about 10% of the total volume of all sedimentary rocks.<ref>{{cite web |url=http://www.mine-engineer.com/mining/mineral/calcite.htm|work=mine-engineer.com | title=Calcite | accessdate=2008-02-13}}</ref><ref>{{cite encyclopedia |url=http://encarta.msn.com/encyclopedia_761565838/Limestone_(mineral).html | title=Limestone (mineral) |accessdate=2008-02-13|archiveurl=http://www.webcitation.org/query?id=1257008095152489|archivedate=2009-10-31|deadurl=yes}}</ref> |
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Limestone is partially soluble, especially in acid, and therefore forms many erosional landforms. These include [[limestone pavement]]s, [[pot hole]]s, [[cenote]]s, caves and gorges. Such erosion landscapes are known as [[karsts]]. Limestone is less [[resistance (geology)|resistant]] than most [[igneous]] rocks, but more resistant than most other [[sedimentary rocks]]. It is therefore usually associated with hills and [[downland]], and occurs in regions with other sedimentary rocks, typically clays. |
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Karst [[topography]] and caves develop in limestone rocks due to their [[solubility]] in dilute [[acid]]ic [[groundwater]]. The [[solubility]] of limestone in water and weak acid solutions leads to [[karst]] landscapes. Regions overlying limestone bedrock tend to have fewer visible above-ground sources (ponds and streams), as surface water easily drains downward through [[joints]] in the limestone. While draining, water and organic acid from the soil slowly (over thousands or millions of years) enlarges these cracks, dissolving the calcium carbonate and carrying it away in [[solution]]. Most [[cave]] systems are through limestone bedrock. Cooling groundwater or mixing of different groundwaters will also create conditions suitable for cave formation. |
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Coastal limestones are often eroded by organisms which bore into the rock by various means. This process is known as [[bioerosion]]. It is most common in the tropics, and it is known throughout the [[fossil record]] (see Taylor and Wilson, 2003). |
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Bands of limestone emerge from the Earth's surface in often spectacular rocky outcrops and islands. Examples include the [[The Burren|Burren]] in Co. Clare, Ireland; the [[Verdon Gorge]] in France; [[Malham Cove]] in [[North Yorkshire]] and the [[Isle of Wight]],<ref>{{cite web | url=http://www.iwight.com/council/documents/policies_and_plans/udp/2002_pdfs/minerals.pdf|format=PDF| title=Isle of Wight, Minerals | accessdate=2006-10-08}}</ref> England; on [[F泶]] near the Swedish island of [[Gotland]], the [[Niagara Escarpment]] in Canada/United States, [[Notch Peak]] in Utah, the [[Ha Long Bay]] National Park in Vietnam and the hills around the [[Lijiang River]] and [[Guilin]] city in China. |
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The [[Florida Keys]], islands off the south coast of [[Florida]], are composed mainly of [[oolite|oolitic]] limestone (the Lower Keys) and the carbonate skeletons of [[coral]] reefs (the Upper Keys), which thrived in the area during interglacial periods when sea level was higher than at present. |
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Unique habitats are found on [[alvar]]s, extremely level expanses of limestone with thin soil mantles. The largest such expanse in Europe is the [[Stora Alvaret]] on the island of [[and]], Sweden. Another area with large quantities of limestone is the island of Gotland, Sweden. Huge quarries in northwestern Europe, such as those of Mount Saint Peter (Belgium/Netherlands), extend for more than a hundred kilometers. |
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The world's largest limestone quarry is at [[Michigan Limestone and Chemical Company]] in [[Rogers City, Michigan]].<ref>[http://www.michmarkers.com/startup.asp?startpage=S0214.htm Michigan Markers]. Michmarkers.com. Retrieved on 2011-11-25.</ref> |
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== Uses == |
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Limestone is very common in architecture, especially in Europe and North America. Many landmarks across the world, including the [[Great Pyramid of Giza|Great Pyramid]] and its associated [[Giza pyramid complex|complex]] in Giza, Egypt, are made of limestone. So many buildings in [[Kingston, Ontario|Kingston]], [[Ontario]], [[Canada]] were constructed from it that it is nicknamed the 'Limestone City'.<ref>{{cite web |url= http://www.citylifeontario.com/kingston/ | title=Welcome to the Limestone City |accessdate=2008-02-13}}</ref> On the island of [[Malta]], a variety of limestone called Globigerina limestone was, for a long time, the only building material available, and is still very frequently used on all types of buildings and sculptures. Limestone is readily available and relatively easy to cut into blocks or more elaborate carving. It is also long-lasting and stands up well to exposure. However, it is a very heavy material, making it impractical for tall buildings, and relatively expensive as a building material. |
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[[File:Gizeh Cheops BW 1.jpg|thumb|The [[Great Pyramid of Giza]], one of the [[Seven Wonders of the Ancient World]]; its outside cover is made entirely from limestone.]] |
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[[Image:Riley (Kansas) County Courthouse 1.jpg|thumb|right|Courthouse built of limestone in [[Manhattan, Kansas]]]] |
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[[Image:Litography press with map of Moosburg 01.jpg|thumb|right|A limestone plate with a negative map of [[Moosburg]] in Bavaria is prepared for a [[lithography]] print.]] |
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Limestone was most popular in the late 19th and early 20th centuries. Train stations, banks and other structures from that era are normally made of limestone. It is used as a facade on some skyscrapers, but only in thin plates for covering, rather than solid blocks. In the United States, Indiana, most notably the Bloomington area, has long been a source of high quality quarried limestone, called [[Indiana limestone]]. Many famous buildings in London are built from [[Portland limestone]]. |
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Limestone was also a very popular building block in the Middle Ages in the areas where it occurred, since it is hard, durable, and commonly occurs in easily accessible surface exposures. Many medieval churches and castles in Europe are made of limestone. [[Beer stone]] was a popular kind of limestone for medieval buildings in southern England. |
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Limestone and (to a lesser extent) marble are reactive to acid solutions, making [[acid rain]] a significant problem to the preservation of artifacts made from this stone. Many limestone statues and building surfaces have suffered severe damage due to acid rain. Acid-based cleaning chemicals can also etch limestone, which should only be cleaned with a neutral or mild alkaline-based cleaner. |
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Other uses include: |
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* It is the raw material for the manufacture of [[quicklime]] (calcium oxide), [[slaked lime]] (calcium hydroxide), [[cement]] and [[mortar (masonry)|mortar]]. |
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* Pulverized limestone is used as a soil conditioner to neutralize acidic soils. |
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* It is crushed for use as [[construction aggregate|aggregate]]شhe solid base for many roads. |
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* [[Geological formation]]s of limestone are among the best [[petroleum reservoir]]s; |
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* As a [[reagent]] in [[flue-gas desulfurization]], it reacts with [[sulfur dioxide]] for air pollution control. |
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* [[Glass making]], in some circumstances, uses limestone. |
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* It is added to toothpaste, paper, plastics, paint, tiles, and other materials as both white pigment and a cheap filler. |
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* It can suppress methane explosions in underground coal mines. |
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* Purified, it is added to bread and cereals as a source of calcium. |
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* Calcium levels in livestock feed are supplemented with it, such as for poultry (when ground up).<ref>{{cite web |url= http://poultryone.com/articles/calcium.html| title=PoultyOne article on Calcium for chickens}}</ref> |
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* It can be used for remineralizing and increasing the alkalinity of purified water to prevent pipe corrosion and to restore essential nutrient levels.<ref>{{cite web |url= http://www.who.int/water_sanitation_health/dwq/nutconsensus/en/| title=Nutrient minerals in drinking-water and the potential health consequences of consumption of demineralized and remineralized and altered mineral content drinking-water: Consensus of the meeting|work=World Health Organization report}}</ref> |
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* Used in [[blast furnace]]s, limestone extracts [[iron]] from its [[Iron ore|ore]]. |
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* It is often found in medicines and cosmetics. |
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* It is used in sculptures because of its suitability for carving. |
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==Gallery== |
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<gallery> |
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Image:OrdOutcropTN.JPG|A stratigraphic section of [[Ordovician]] limestone exposed in central [[Tennessee]], U.S. The less-resistant and thinner beds are composed of [[shale]]. The vertical lines are drill holes for explosives used during road construction. |
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Image:CarmelOoids.jpg|Thin-section view of a Middle [[Jurassic]] limestone in southern Utah. The round grains are [[ooid]]s; the largest is 1.2 mm in diameter. This limestone is an oosparite. |
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Image:Limestone_etched_section_KopeFm_new.jpg|Photo and etched section of a sample of fossiliferous limestone from the [[Kope Formation]] (Upper Ordovician) near Cincinnati, Ohio. |
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Image:BrassfieldEncrinite042112.jpg|Biosparite limestone of the [[Brassfield Formation]] (Lower [[Silurian]]) near Fairborn, Ohio, showing grains mainly composed of [[crinoid]] fragments. |
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</gallery> |
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== See also == |
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{{Commons category|Limestones}} |
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* [[කැල්සියම් කාබනේට්]] |
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* [[Chalk]] |
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* [[Coral sand]] |
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* [[Kurkar]] |
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* [[In Praise of Limestone]] |
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* [[List of types of limestone]] by location |
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== References == |
== References == |
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{{Reflist}} |
{{Reflist}} |
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== Further reading == |
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* Taylor, P.D. and Wilson, M.A., 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1ֱ03.[http://www3.wooster.edu/geology/Taylor%26Wilson2003.pdf] |
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* Folk RL, (1974) Petrology of Sedimentary Rocks, Hemphill Publishing, Austin, Texas |
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* Dunham, R.J., 1962, ''Classification of carbonate rocks according to depositional textures'', in Ham W.E. (ed.), Classification of carbonate rocks: Am. Assoc. Petroleum Geologists Mem. 1,p. 108-121 |
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* Robert S. Boynton-Chemistry and technology of lime and limestone- Wiley (1980) - 578 pages - ISBN 0471027715 |
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[[Category:හුණු ගල්| ]] |
[[Category:හුණු ගල්| ]] |
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[[Category:Sedimentary rocks]] |
[[Category:Sedimentary rocks]] |
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08:47, 24 ජූනි 2013 තෙක් සංශෝධනය
| අවසාදිත පාෂාණ | |
 නවසීලන්තයේ, වයිටොමෝ දිස්ත්‍රික්කයේ හුණු ගල් | |
| සංයුතිය | |
|---|---|
| කැල්සියම් කාබනේට්: අකාබනික ස්ඵටිකරූපී කැල්සයිට් සහ/හෝ කාබනික චූර්ණමය ද්‍රව්‍යය |
හුණු ගල් යනු කැල්සියම් කාබනේට් (CaCO3)හි විවිධ ස්ඵටිකරූපී ආකාර වන කැල්සයිට් සහ ඇරගනයිට් ඛනිජයන්ගෙන් විශාල වශයෙන් සමන්විත වන අවසාදිත පාෂාණ විශේෂයකි. බොහෝ හුණු ගල් සෑදී ඇත්තේ කොරල් හෝ ෆොරමිනිෆරා වැනි මුහුදු ජීවීන්ගේ අස්ථි කොටස් වලිනි.
සමස්ත අවසාදිත පාෂාණ ඝන ප්‍රමාණයෙන් 10% පමණ හුණු ගල් වේ. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. බොහෝ ගුහා සංකීර්ණ පිහිටා ඇත්තේ හුණු ගල්හි පිහිටි පාෂාණ හරහා ය.
හුණු ගල්හි බොහෝ භාවිතයන් පවතී: ගොඩනැගිලි ද්‍රව්‍යයක් ලෙස, මාර්ගයන්හි පාදම් සඳහා සමූහනකාරකයක් ලෙස, සුදු වර්ණකයක් ලෙස හෝ දන්තාලේප හෝ තීන්ත වැනි නිෂ්පාදනයන්හි පිරවුම් ද්‍රව්‍යයක් ලෙස සහ as a chemical feedstock.
1778 දී හුණු ගල් වලින් ඩොලමයිට් ප්‍රභේදනය කර හඳුනා ගත් ප්‍රථම භූ විද්‍යාඥයා Belsazar Hacquet වේ. [1]
විස්තරය
අනෙකුත් බොහෝ අවසාදිත පාෂාණ මෙන්ම, හුණු ගල් බොහොමයක් කණිකා වලින් සැදුම් ලත් වේ. හුණු ගල්හි ඇති බොහෝ කණිකා කොරල් හෝ ෆොරමිනිෆරා වැනි මුහුදු ජීවීන්ගේ අස්ථි කොටස් වේ. හුණු ගල් වල අඩංගු වන අනෙකුත් කාබනේට කණිකා වනුයේ ooids, peloids, intraclasts, සහ extraclasts වේ. මෙම ජීවීන් ඇරගනයිට් හෝ කැල්සයිට් වලින් සැදුම් ලත් කවච ශ්‍රාවය කරන අතර, එම ජීවීන්ගේ මරණයෙන් පසු මෙම කවච පසෙකලනු ලැබේ.
References
- ↑ Kranjc, Andrej (2006). "Balthasar Hacquet (1739/40-1815), the Pionneer of Karst Geomorphologists". Acta Carsologica. Institute for the Karst Research, Scientific Research Centre, Slovenian Academy of Sciences and Arts. 35 (2). ISSN 0583-6050.