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58-536: Lias is a Middle English term for hard limestone, used in this specific sense by geologists since 1833. In the past, geologists used Lias not only for the sequence of rock layers, but also for the timespan during which they were formed. It was thus an alternative name for the Early Jurassic epoch of the geologic timescale . It is now more specifically known that the Lias is Rhaetian to Toarcian in age (over

116-423: A desiccator alongside ammonium carbonate [NH 4 ] 2 CO 3 . In the desiccator, ammonium carbonate is exposed to air and decomposes into ammonia , carbon dioxide, and water . The carbon dioxide then diffuses into the aqueous solution of calcium chloride, reacts with the calcium ions and the water, and forms calcium carbonate. The thermodynamically stable form of CaCO 3 under normal conditions

174-519: A food additive it is designated E170 , and it has an INS number of 170. Used as an acidity regulator , anticaking agent , stabilizer or color it is approved for usage in the EU, US and Australia and New Zealand . It is "added by law to all UK milled bread flour except wholemeal". It is used in some soy milk and almond milk products as a source of dietary calcium; at least one study suggests that calcium carbonate might be as bioavailable as

232-452: A phosphate binder for the treatment of hyperphosphatemia (primarily in patients with chronic kidney failure ). It is used in the pharmaceutical industry as an inert filler for tablets and other pharmaceuticals . Calcium carbonate is used in the production of calcium oxide as well as toothpaste and has seen a resurgence as a food preservative and color retainer, when used in or with products such as organic apples. Calcium carbonate

290-410: A filler in paper because they are cheaper than wood fiber . Printing and writing paper can contain 10–20% calcium carbonate. In North America, calcium carbonate has begun to replace kaolin in the production of glossy paper . Europe has been practicing this as alkaline papermaking or acid-free papermaking for some decades. PCC used for paper filling and paper coatings is precipitated and prepared in

348-524: A period of c. 20 million years between 200 to 180 million years ago ) and thus also includes a part of the Triassic . The use of the name "Lias" for a unit of time is therefore slowly disappearing. In southern England , the Lias Group is often divided into Lower, Middle and Upper subgroups. In Southern England the Lias is divided into the following formations (from top to base): In

406-657: A problem that makes correlation between sections in different parts of the world difficult. If this biostratigraphical indicator is used, then technically the Lias Group —a lithostratigraphical division—spans the Jurassic / Triassic boundary. There are extensive Liassic outcrops around the coast of the United Kingdom , in particular in Glamorgan , North Yorkshire and Dorset . The 'Jurassic Coast' of Dorset

464-523: A pure quarried source (usually marble ). Alternatively, calcium carbonate is prepared from calcium oxide . Water is added to give calcium hydroxide then carbon dioxide is passed through this solution to precipitate the desired calcium carbonate, referred to in the industry as precipitated calcium carbonate (PCC) This process is called carbonatation : In a laboratory, calcium carbonate can easily be crystallized from calcium chloride ( CaCl 2 ), by placing an aqueous solution of CaCl 2 in

522-399: A requirement that becomes important at high usage temperatures. Here the percentage is often 20–40%. It also routinely used as a filler in thermosetting resins (sheet and bulk molding compounds) and has also been mixed with ABS , and other ingredients, to form some types of compression molded "clay" poker chips . Precipitated calcium carbonate, made by dropping calcium oxide into water,

580-532: A resist to prevent glass from sticking to kiln shelves when firing glazes and paints at high temperature. In ceramic glaze applications, calcium carbonate is known as whiting , and is a common ingredient for many glazes in its white powdered form. When a glaze containing this material is fired in a kiln, the whiting acts as a flux material in the glaze. Ground calcium carbonate is an abrasive (both as scouring powder and as an ingredient of household scouring creams), in particular in its calcite form, which has

638-478: A source of dietary calcium, but are also a practical industrial source. Dark green vegetables such as broccoli and kale contain dietarily significant amounts of calcium carbonate, but they are not practical as an industrial source. Annelids in the family Lumbricidae , earthworms, possess a regionalization of the digestive track called calciferous glands , Kalkdrüsen, or glandes de Morren, that processes calcium and CO 2 into calcium carbonate, which

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696-870: A variety of shapes and sizes having characteristic narrow particle size distributions and equivalent spherical diameters of 0.4 to 3 micrometers. Calcium carbonate is widely used as an extender in paints , in particular matte emulsion paint where typically 30% by weight of the paint is either chalk or marble. It is also a popular filler in plastics. Some typical examples include around 15–20% loading of chalk in unplasticized polyvinyl chloride (uPVC) drainpipes , 5–15% loading of stearate -coated chalk or marble in uPVC window profile. PVC cables can use calcium carbonate at loadings of up to 70 phr (parts per hundred parts of resin) to improve mechanical properties (tensile strength and elongation) and electrical properties (volume resistivity). Polypropylene compounds are often filled with calcium carbonate to increase rigidity,

754-534: Is hexagonal β- CaCO 3 (the mineral calcite ). Other forms can be prepared, the denser (2.83 g/cm ) orthorhombic λ- CaCO 3 (the mineral aragonite ) and hexagonal μ- CaCO 3 , occurring as the mineral vaterite . The aragonite form can be prepared by precipitation at temperatures above 85 °C; the vaterite form can be prepared by precipitation at 60 °C. Calcite contains calcium atoms coordinated by six oxygen atoms; in aragonite they are coordinated by nine oxygen atoms. The vaterite structure

812-402: Is a common filler material for latex gloves with the aim of achieving maximum saving in material and production costs. Fine ground calcium carbonate (GCC) is an essential ingredient in the microporous film used in diapers and some building films, as the pores are nucleated around the calcium carbonate particles during the manufacture of the film by biaxial stretching. GCC and PCC are used as

870-448: Is about 0.035 kPa. At temperatures above 550 °C the equilibrium CO 2 pressure begins to exceed the CO 2 pressure in air. So above 550 °C, calcium carbonate begins to outgas CO 2 into air. However, in a charcoal fired kiln, the concentration of CO 2 will be much higher than it is in air. Indeed, if all the oxygen in the kiln is consumed in the fire, then

928-411: Is also used in the purification of iron from iron ore in a blast furnace . The carbonate is calcined in situ to give calcium oxide , which forms a slag with various impurities present, and separates from the purified iron. In the oil industry , calcium carbonate is added to drilling fluids as a formation-bridging and filtercake-sealing agent; it is also a weighting material which increases

986-403: Is balanced by the rate of dissolution due to the conditions present. Deep in the ocean, the temperature drops and pressure increases. Increasing pressure also increases the solubility of calcium carbonate. Calcium carbonate is unusual in that its solubility increases with decreasing temperature. The carbonate compensation depth ranges from 4,000 to 6,000 meters below sea level in modern oceans, and

1044-461: Is in the construction industry, either as a building material, or limestone aggregate for road building, as an ingredient of cement , or as the starting material for the preparation of builders' lime by burning in a kiln . However, because of weathering mainly caused by acid rain , calcium carbonate (in limestone form) is no longer used for building purposes on its own, but only as a raw primary substance for building materials. Calcium carbonate

1102-526: Is interest in understanding whether or not it can affect pesticide adsorption and desorption in calcareous soil. Calcium carbonate is a key ingredient in many household cleaning powders like Comet and is used as a scrubbing agent. In 1989, a researcher, Ken Simmons, introduced CaCO 3 into the Whetstone Brook in Massachusetts . His hope was that the calcium carbonate would counter

1160-479: Is later excreted into the dirt. The function of these glands is unknown but is believed to serve as a CO 2 regulation mechanism within the animals' tissues. This process is ecologically significant, stabilizing the pH of acid soils . Beyond Earth, strong evidence suggests the presence of calcium carbonate on Mars . Signs of calcium carbonate have been detected at more than one location (notably at Gusev and Huygens craters). This provides some evidence for

1218-425: Is misleading. Calcium carbonate exists in equilibrium with calcium oxide and carbon dioxide at any temperature. At each temperature there is a partial pressure of carbon dioxide that is in equilibrium with calcium carbonate. At room temperature the equilibrium overwhelmingly favors calcium carbonate, because the equilibrium CO 2 pressure is only a tiny fraction of the partial CO 2 pressure in air, which

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1276-404: Is not fully understood. Magnesium carbonate ( MgCO 3 ) has the calcite structure, whereas strontium carbonate ( SrCO 3 ) and barium carbonate ( BaCO 3 ) adopt the aragonite structure, reflecting their larger ionic radii . Calcium carbonate crystallizes in three anhydrous polymorphs , of which calcite is the thermodynamically most stable at room temperature, aragonite

1334-524: Is often associated with the pioneering work of Mary Anning of Lyme Regis . The facies of the Lower Jurassic in this area are predominantly of clays , thin limestones and siltstones , deposited under fully marine conditions. Lias Group strata form imposing cliffs on the Vale of Glamorgan coast, in southern Wales . Stretching for around 14 miles (23 km) between Cardiff and Porthcawl ,

1392-551: Is only slightly less so, and vaterite is the least stable. The calcite crystal structure is trigonal , with space group R 3 c (No. 167 in the International Tables for Crystallography ), and Pearson symbol hR10. Aragonite is orthorhombic , with space group Pmcn (No 62), and Pearson Symbol oP20. Vaterite is composed of at least two different coexisting crystallographic structures. The major structure exhibits hexagonal symmetry in space group P6 3 /mmc,

1450-542: Is probably paraphyletic ). All these plesiosaurs had medium-sized necks and large heads. In the Toarcian , at the end of the Early Jurassic, the thalattosuchians (marine " crocodiles ") appeared, as did new genera of ichthyosaurs ( Stenopterygius , Eurhinosaurus , and the persistently primitive Suevoleviathan ) and plesiosaurs (the elasmosaurs (long-necked) Microcleidus and Occitanosaurus , and

1508-521: Is saturated with carbon dioxide to form the soluble calcium bicarbonate . This reaction is important in the erosion of carbonate rock , forming caverns , and leads to hard water in many regions. An unusual form of calcium carbonate is the hexahydrate ikaite , CaCO 3 ·6H 2 O . Ikaite is stable only below 8 °C. The vast majority of calcium carbonate used in industry is extracted by mining or quarrying. Pure calcium carbonate (such as for food or pharmaceutical use), can be produced from

1566-432: Is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale . It has medical use as a calcium supplement or as an antacid , but excessive consumption can be hazardous and cause hypercalcemia and digestive issues. Calcium carbonate shares the typical properties of other carbonates . Notably it Calcium carbonate reacts with water that

1624-493: Is then slaked in fresh water to produce a calcium hydroxide suspension for the precipitation of impurities in raw juice during carbonatation . Calcium carbonate in the form of chalk has traditionally been a major component of blackboard chalk. However, modern manufactured chalk is mostly gypsum , hydrated calcium sulfate CaSO 4 ·2H 2 O . Calcium carbonate is a main source for growing biorock . Precipitated calcium carbonate (PCC), pre-dispersed in slurry form,

1682-406: Is used by itself or with additives as a white paint, known as whitewashing . Calcium carbonate is added to a wide range of trade and do it yourself adhesives, sealants, and decorating fillers. Ceramic tile adhesives typically contain 70% to 80% limestone. Decorating crack fillers contain similar levels of marble or dolomite. It is also mixed with putty in setting stained glass windows, and as

1740-577: Is used therapeutically as phosphate binder in patients on maintenance haemodialysis . It is the most common form of phosphate binder prescribed, particularly in non-dialysis chronic kidney disease. Calcium carbonate is the most commonly used phosphate binder, but clinicians are increasingly prescribing the more expensive, non-calcium-based phosphate binders, particularly sevelamer . Excess calcium from supplements, fortified food, and high-calcium diets can cause milk-alkali syndrome , which has serious toxicity and can be fatal. In 1915, Bertram Sippy introduced

1798-836: The Lower Jurassic Series ) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic–Jurassic extinction event , 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.7 ±0.8 Ma. Certain rocks of marine origin of this age in Europe are called " Lias " and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic . There are two possible origins for

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1856-429: The oceanic crust is subducted under a continental plate sediments will be carried down to warmer zones in the asthenosphere and lithosphere . Under these conditions calcium carbonate decomposes to produce carbon dioxide which, along with other gases, give rise to explosive volcanic eruptions . The carbonate compensation depth (CCD) is the point in the ocean where the rate of precipitation of calcium carbonate

1914-518: The pliosaur Hauffiosaurus ). On land, a number of new types of dinosaurs—the heterodontosaurids , scelidosaurs , stegosaurs , and tetanurans —appeared, and joined those groups like the coelophysoids , prosauropods and the sauropods that had continued over from the Triassic. Accompanying them as small carnivores were the sphenosuchian and protosuchid crocodilians. In the air, new types of pterosaurs replaced those that had died out at

1972-463: The "Sippy regimen" of hourly ingestion of milk and cream, and the gradual addition of eggs and cooked cereal, for 10 days, combined with alkaline powders, which provided symptomatic relief for peptic ulcer disease. Over the next several decades, the Sippy regimen resulted in kidney failure , alkalosis , and hypercalcaemia , mostly in men with peptic ulcer disease. These adverse effects were reversed when

2030-462: The 1970s, such liming has been practiced on a large scale in Sweden to mitigate acidification and several thousand lakes and streams are limed repeatedly. Calcium carbonate is also used in flue-gas desulfurization applications eliminating harmful SO 2 and NO 2 emissions from coal and other fossil fuels burnt in large fossil fuel power stations. Calcium carbonate is commonly used in

2088-653: The Cleveland Basin. In some areas there is a stratigraphic hiatus , and the rocks are overlain by Cretaceous marine sediments. There are restricted outcrops of Lias rocks on the west coast of Scotland where, in the Sea of the Hebrides depositional basin on Skye , Raasay and Mull , the Broadford Beds Formation , Pabay Shale Formation and overlying Scalpay Sandstone Formation are assigned to

2146-887: The East Midlands Shelf the Lias is divided into the following formations (from top to base): In the Cleveland Basin in Yorkshire the Lias is divided into the following formations (from top to base): In South Wales only the Blue Lias is present. The Lias is underlain by the Late Triassic Penarth Group , and overlain by the Inferior Oolite in most of England and the Dogger Formation or Ravenscar Group in

2204-521: The Lias Group. In Dutch lithostratigraphy, the name Lias has no official status, however, it is often used for the lower part of the Altena Group in the subsurface of the Netherlands and the southern North Sea. In northern Germany, the Lias Group consists of nine formations (from top to base): Early Jurassic The Early Jurassic Epoch (in chronostratigraphy corresponding to

2262-831: The ability to grow all three crystal polymorphs of calcium carbonate, mainly as protection (shells) and muscle attachments. Moreover, they exhibit a remarkable capability of phase selection over calcite and aragonite, and some organisms can switch between the two polymorphs. The ability of phase selection is usually attributed to the use of specific macromolecules or combinations of macromolecules by such organisms. Calcite , aragonite and vaterite are pure calcium carbonate minerals. Industrially important source rocks which are predominantly calcium carbonate include limestone , chalk , marble and travertine . Eggshells , snail shells and most seashells are predominantly calcium carbonate and can be used as industrial sources of that chemical. Oyster shells have enjoyed recent recognition as

2320-438: The acid in the stream from acid rain and save the trout that had ceased to spawn. Although his experiment was a success, it did increase the amount of aluminium ions in the area of the brook that was not treated with the limestone. This shows that CaCO 3 can be added to neutralize the effects of acid rain in river ecosystems. Currently calcium carbonate is used to neutralize acidic conditions in both soil and water. Since

2378-715: The acidic Devonian and Carboniferous soils of the West Country ); the Cornish would pronounce the layers of limestone as ' laiyers ' or ' lias '; leac is Gaelic for "flat stone". There has been some debate over the actual base of the Hettangian Stage, and so of the Jurassic System itself. Biostratigraphically , the first appearance of psiloceratid ammonites has been used; but this depends on relatively complete ammonite faunas being present,

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2436-563: The calcium in cow's milk . Calcium carbonate is also used as a firming agent in many canned and bottled vegetable products. Several calcium supplement formulations have been documented to contain the chemical element lead , posing a public health concern. Lead is commonly found in natural sources of calcium. Agricultural lime , powdered chalk or limestone, is used as a cheap method of neutralising acidic soil , making it suitable for planting, also used in aquaculture industry for pH regulation of pond soil before initiating culture. There

2494-414: The density of drilling fluids to control the downhole pressure. Calcium carbonate is added to swimming pools , as a pH corrector for maintaining alkalinity and offsetting the acidic properties of the disinfectant agent. It is also used as a raw material in the refining of sugar from sugar beet ; it is calcined in a kiln with anthracite to produce calcium oxide and carbon dioxide. This burnt lime

2552-609: The end of the Triassic. But in the undergrowth were various types of early mammals, as well as tritylodont synapsids , lizard-like sphenodonts , and early lissamphibians . Calcium carbonate Calcium carbonate is a chemical compound with the chemical formula Ca CO 3 . It is a common substance found in rocks as the minerals calcite and aragonite , most notably in chalk and limestone , eggshells , gastropod shells , shellfish skeletons and pearls . Materials containing much calcium carbonate or resembling it are described as calcareous . Calcium carbonate

2610-431: The formation of calcite and/or promote the nucleation of aragonite. For example, the formation of aragonite is promoted by the presence of magnesium ions, or by using proteins and peptides derived from biological calcium carbonate. Some polyamines such as cadaverine and Poly(ethylene imine) have been shown to facilitate the formation of aragonite over calcite. Organisms, such as molluscs and arthropods , have shown

2668-417: The least stable polymorph crystallizes first, followed by the crystallization of different polymorphs via a sequence of increasingly stable phases. However, aragonite, whose stability lies between those of vaterite and calcite, seems to be the exception to this rule, as aragonite does not form as a precursor to calcite under ambient conditions. Aragonite occurs in majority when the reaction conditions inhibit

2726-468: The microscopic level. However, it also leaves specimens vulnerable to weathering when exposed to the surface. Trilobite populations were once thought to have composed the majority of aquatic life during the Cambrian , due to the fact that their calcium carbonate-rich shells were more easily preserved than those of other species, which had purely chitinous shells. The main use of calcium carbonate

2784-464: The minor structure is still unknown. All three polymorphs crystallize simultaneously from aqueous solutions under ambient conditions. In additive-free aqueous solutions, calcite forms easily as the major product, while aragonite appears only as a minor product. At high saturation, vaterite is typically the first phase precipitated, which is followed by a transformation of the vaterite to calcite. This behavior seems to follow Ostwald's rule , in which

2842-555: The name Lias: the first reason is it was taken by a geologist from an English quarryman 's dialect pronunciation of the word "layers"; secondly, sloops from north Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias and Carboniferous limestone from South Wales was used throughout North Devon/North Cornwall as it contains calcium carbonate to 'sweeten' (i.e.neutralise)

2900-403: The partial pressure of CO 2 in the kiln can be as high as 20 kPa. The table shows that this partial pressure is not achieved until the temperature is nearly 800 °C. For the outgassing of CO 2 from calcium carbonate to happen at an economically useful rate, the equilibrium pressure must significantly exceed the ambient pressure of CO 2 . And for it to happen rapidly,

2958-440: The past presence of liquid water. Carbonate is found frequently in geologic settings and constitutes an enormous carbon reservoir . Calcium carbonate occurs as aragonite , calcite and dolomite as significant constituents of the calcium cycle . The carbonate minerals form the rock types: limestone , chalk , marble , travertine , tufa , and others. In warm, clear tropical waters corals are more abundant than towards

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3016-446: The plastic industry as a filler. When it is incorporated in a plastic material, it can improve the hardness, stiffness, dimensional stability and processability of the material. Calcination of limestone using charcoal fires to produce quicklime has been practiced since antiquity by cultures all over the world. The temperature at which limestone yields calcium oxide is usually given as 825 °C, but stating an absolute threshold

3074-492: The poles where the waters are cold. Calcium carbonate contributors, including plankton (such as coccoliths and planktic foraminifera ), coralline algae , sponges , brachiopods , echinoderms , bryozoa and mollusks , are typically found in shallow water environments where sunlight and filterable food are more abundant. Cold-water carbonates do exist at higher latitudes but have a very slow growth rate. The calcification processes are changed by ocean acidification . Where

3132-657: The regimen stopped, but it was fatal in some patients with protracted vomiting. Milk-alkali syndrome declined in men after effective treatments for peptic ulcer disease arose. Since the 1990s it has been most frequently reported in women taking calcium supplements above the recommended range of 1.2 to 1.5 grams daily, for prevention and treatment of osteoporosis, and is exacerbated by dehydration . Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake. Excessive calcium intake can lead to hypercalcemia, complications of which include vomiting, abdominal pain and altered mental status. As

3190-555: The relatively low hardness level of 3 on the Mohs scale , and will therefore not scratch glass and most other ceramics , enamel , bronze , iron , and steel , and have a moderate effect on softer metals like aluminium and copper . A paste made from calcium carbonate and deionized water can be used to clean tarnish on silver . Calcium carbonate is widely used medicinally as an inexpensive dietary calcium supplement for gastric antacid (such as Tums and Eno ). It may be used as

3248-612: The remarkable layers of these cliffs, situated on the Bristol Channel are a rhythmic decimetre scale repetition of limestone and mudstone formed as a late Triassic desert was inundated by the sea. During this period, ammonoids , which had almost died out at the end-of-Triassic extinction, radiated out into a huge diversity of new forms with complex suture patterns (the ammonites proper). Ammonites evolved so rapidly, and their shells are so often preserved, that they serve as important zone fossils . There were several distinct waves of ammonite evolution in Europe alone. The Early Jurassic

3306-502: The various polymorphs (calcite, aragonite) have different compensation depths based on their stability. Calcium carbonate can preserve fossils through permineralization . Most of the vertebrate fossils of the Two Medicine Formation —a geologic formation known for its duck-billed dinosaur eggs—are preserved by CaCO 3 permineralization. This type of preservation conserves high levels of detail, even down to

3364-476: Was an important time in the evolution of the marine reptiles. The Hettangian saw the already existing Rhaetian ichthyosaurs and plesiosaurs continuing to flourish, while at the same time a number of new types of these marine reptiles appeared, such as Ichthyosaurus and Temnodontosaurus among the ichthyosaurs, and Eurycleidus , Macroplata , and Rhomaleosaurus among the plesiosaurs (all Rhomaleosauridae , although as currently defined this group

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