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{{About|the metallic element|the place|Calcium, New York}}
{{pp-semi-vandalism|small=yes|}}{{Pp-move-indef}}
{{Infobox calcium}}
'''Calcium''' ({{IPAc-en|icon|ˈ|k|æ|l|s|i|əm}} {{respell|KAL|see-əm}}) is the [[chemical element]] with the symbol '''Ca''' and [[atomic number]] 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray [[alkaline earth metal]], and is the fifth most abundant element by mass in the [[Earth]]'s [[Crust (geology)|crust]]. Calcium is also the fifth most abundant dissolved ion in [[seawater]] by both molarity and mass, after [[sodium]], [[chloride]], [[magnesium]], and [[sulfate]].<ref>{{cite book|title=Handbook of method for the analysis of the various parameters of the carbon dioxide system in sea water, version 2|author= Dickson, A. G. and Goyet, C. |publisher =ORNL/CDIAC-74|year=1994|url=http://cdiac.esd.ornl.gov/ftp/cdiac74/chapter5.pdf| chapter=5}}</ref>

Calcium is essential for living [[organism]]s, particularly in [[Cell (biology)|cell]] [[physiology]], where movement of the calcium ion Ca<sup>2+</sup> into and out of the [[cytoplasm]] functions as a signal for many cellular processes. As a major material used in mineralization of bones and shells, calcium is the most abundant [[metal]] by mass in many [[animal]]s.

==Notable characteristics==
[[File:FlammenfärbungCa.png|thumb|upright|left|[[Flame test]]. Brick red color originates from calcium.]]
Chemically calcium is reactive and soft for a metal (though harder than lead, it can be cut with a knife with difficulty). It is a silvery metallic element that must be extracted by [[electrolysis]] from a fused salt like [[calcium chloride]].<ref name="pauling">{{cite book|author=Pauling, Linus|title= General Chemistry|page= 627|year= 1970|publisher=Dover Publications|isbn=0716701499}}</ref> Once produced, it rapidly forms a gray-white [[oxide]] and [[nitride]] coating when exposed to air. In bulk-form (typically as chips or "turnings") the metal is somewhat difficult to ignite, more so even than magnesium chips; but when lit, the metal burns in air with a brilliant high-intensity red light. Calcium metal reacts with [[water]], evolving hydrogen gas at a rate rapid enough to be noticeable, but not fast enough at room temperature to generate much heat. In powdered form, however, the reaction with water is extremely rapid, as the increased surface area of the powder accelerates the reaction with the water. Part of the slowness of the calcium-water reaction results from the metal being partly protected by insoluble white [[calcium hydroxide]]. In water solutions of acids, where this salt is soluble, calcium reacts vigorously.

Calcium, with a density of 1.55 g/cm<sup>3</sup>, is the lightest of the alkali earth metals; magnesium ([[specific gravity]] 1.74) and beryllium (1.84) are more dense, although lighter in atomic mass. From strontium onward, the alkali earth metals become more dense with increasing atomic mass.

Calcium has a higher electrical resistivity than [[copper]] or [[aluminium]], yet weight-for-weight, due to its much lower density, it is a rather better conductor than either. However, its use in terrestrial applications is usually limited by its high reactivity with air.

Calcium salts are colorless from any contribution of the calcium, and ionic solutions of calcium (Ca<sup>2+</sup>) are colorless as well. Many calcium salts are not soluble in water. When in solution, the calcium ion to the human taste varies remarkably, being reported as mildly salty, sour, "mineral like" or even "soothing." It is apparent that many animals can taste, or develop a taste, for calcium, and use this sense to detect the mineral in [[salt lick]]s or other sources.<ref>{{cite journal|url=http://physrev.physiology.org/cgi/content/full/81/4/1567 |title=Calcium: Taste, Intake, and Appetite|author=Tordoff, M. G.|volume= 81|issue=4 |page=1567|journal=Physiological Reviews|pmid=11581497|year=2001}}</ref> In human nutrition, soluble calcium salts may be added to tart juices without much effect to the average palate.

Calcium is the fifth most abundant element by mass in the human body, where it is a common cellular ionic messenger with many functions, and serves also as a structural element in bone. It is the relatively high atomic-numbered calcium in the skeleton which causes bone to be radio-opaque. Of the human body's solid components after drying and burning of organics (as for example, after [[cremation]]), about a third of the total "mineral" mass remaining, is the approximately one kilogram of calcium which composes the average skeleton (the remainder being mostly phosphorus and oxygen).

===H and K lines===
Visible spectra of many stars, including the [[Sun]], exhibit strong [[Spectral line|absorption line]]s of singly ionized calcium. Prominent among these are the H-line at 3968.5&nbsp;[[Ångstrom|Å]] and the K line at 3933.7&nbsp;Å of singly ionized calcium, or Ca&nbsp;II. For the Sun and stars with low temperatures, the prominence of the H and K lines can be an indication of strong magnetic activity in the [[chromosphere]]. Measurement of periodic variations of these active regions can also be used to deduce the rotation periods of these stars.<ref>{{cite web
|author=Staff
|year=1995
|url =http://www.mtwilson.edu/hk/
|title =H-K Project
|publisher =Mount Wilson Observatory
|accessdate = 2006-08-10}}</ref>

==Compounds==
Calcium, combined with [[phosphate]] to form [[hydroxylapatite]], is the mineral portion of human and animal bones and teeth. The mineral portion of some [[coral]]s can also be transformed into hydroxylapatite.

[[Calcium hydroxide]] (slaked lime) is used in many chemical refinery processes and is made by heating [[limestone]] at high temperature (above 825 °C) and then carefully adding water to it. When lime is mixed with sand, it hardens into a [[Mortar (masonry)|mortar]] and is turned into [[plaster]] by [[carbon dioxide]] uptake. Mixed with other compounds, lime forms an important part of [[Portland cement]].

[[Calcium carbonate]] (CaCO<sub>3</sub>) is one of the common compounds of calcium. It is heated to form quicklime (CaO), which is then added to water (H<sub>2</sub>O). This forms another material known as slaked lime (Ca(OH)<sub>2</sub>), which is an inexpensive base material used throughout the chemical industry. Chalk, marble, and limestone are all forms of calcium carbonate.

When water percolates through [[limestone]] or other soluble [[carbonate]] rocks, it partially dissolves the rock and causes cave formation and characteristic [[stalactite]]s and [[stalagmite]]s and also forms [[hard water]]. Other important calcium compounds are [[calcium nitrate]], [[calcium sulfide]], [[calcium chloride]], [[calcium carbide]], [[calcium cyanamide]] and [[calcium hypochlorite]].

A few calcium compounds in the oxidation state +1 have also been investigated recently.<ref name="West"/>

==Nucleosynthesis==
Stable Calcium is created in extremely large, extremely hot (over 2.5 billion kelvin) stars. It requires one atom of argon and one atom of helium.{{Citation needed|date=July 2010}}

==Isotopes==
{{Main|Isotopes of calcium}}
Calcium has four stable [[isotope]]s (<sup>40</sup>Ca and <sup>42</sup>Ca through <sup>44</sup>Ca), plus two more isotopes (<sup>46</sup>Ca and [[Calcium-48|<sup>48</sup>Ca]]) that have such long half-lives that for all practical purposes they can be considered stable. The 20% range in relative mass among naturally occurring calcium isotopes is greater than for any element except hydrogen and helium. Calcium also has a [[cosmogenic isotope]], [[radioactive]] <sup>41</sup>Ca, which has a [[half-life]] of 103,000 years. Unlike [[cosmogenic isotope]]s that are produced in the [[Earth's atmosphere|atmosphere]], <sup>41</sup>Ca is produced by [[neutron]] activation of <sup>40</sup>Ca. Most of its production is in the upper metre or so of the soil column, where the cosmogenic neutron flux is still sufficiently strong. <sup>41</sup>Ca has received much attention in stellar studies because it decays to <sup>41</sup>K, a critical indicator of solar-system anomalies.

97% of naturally occurring calcium is in the form of <sup>40</sup>Ca. <sup>40</sup>Ca is one of the daughter products of <sup>40</sup>K decay, along with <sup>40</sup>Ar. While [[K-Ar dating]] has been used extensively in the [[geology|geological]] sciences, the prevalence of <sup>40</sup>Ca in nature has impeded its use in dating. Techniques using [[mass spectrometry]] and a double spike isotope dilution have been used for [[Potassium|K]]-Ca age dating.

The most abundant isotope, <sup>40</sup>Ca, has a nucleus of 20 [[proton]]s and 20 [[neutron]]s. This is the heaviest stable isotope of any element which has equal numbers of protons and neutrons. In supernova explosions, calcium is formed from the reaction of carbon with various numbers of alpha particles (helium nuclei), until the most common calcium isotope (containing 10 helium nuclei) has been synthesized.{{Citation needed|date=April 2008}}

===Isotope fractionation===
As with the isotopes of other elements, a variety of processes fractionate, or alter the relative abundance of, calcium isotopes.<ref>{{cite journal|last1=Russell|first1=WA|last2=Papanastassiou|first2=DA|last3=Tombrello|first3=TA|title=Ca isotope fractionation on the earth and other solar system materials|journal=Geochim Cosmochim Acta|year=1978|volume=42|pages=1075–90|doi=10.1016/0016-7037(78)90105-9}}</ref> The best studied of these processes is the mass dependent [[fractionation]] of calcium isotopes that accompanies the precipitation of calcium minerals, such as [[calcite]], [[aragonite]] and [[apatite]], from solution. Isotopically light calcium is preferentially incorporated into minerals, leaving the solution from which the mineral precipitated enriched in isotopically heavy calcium. At room temperature the magnitude of this fractionation is roughly 0.25‰ (0.025%) per atomic mass unit (AMU). Mass-dependant differences in calcium isotope composition conventionally are expressed the ratio of two isotopes (usually <sup>44</sup>Ca/<sup>40</sup>Ca) in a sample compared to the same ratio in a standard reference material. <sup>44</sup>Ca/<sup>40</sup>Ca varies by about 1% among common earth materials.<ref>{{cite journal|last1=Skulan|first1=J|last2=DePaolo|first2=DJ|title=Calcium isotope fractionation between soft and mineralized tissues as a monitor of calcium use in vertebrates|journal=Proc Natl Acad Sci USA|year=1999|volume=96|pages=13709–13|doi=10.1073/pnas.96.24.13709|pmid=10570137|issue=24|pmc=24129}}</ref>

Calcium isotope fractionation during mineral formation has led to several applications of calcium isotopes. In particular, the 1997 observation by Skulan and DePaolo<ref>{{cite journal|last1=Skulan|first1=J|title=Biological control of calcium isotopic abundances in the global calcium cycle|pmid=17463176|journal=Geochim. Et Cosmochim. Acta|year=1997|volume=61|pages=2505–2510|last2=DePaolo|first2=D |issue=12|doi=10.1016/S0016-7037(97)00047-1|last3=Anbar|first3=AD|last4=Puzas|first4=JE|last5=Shackelford|first5=L|last6=Leblanc|first6=A|last7=Smith|first7=SM}}</ref> that calcium minerals are isotopically lighter than the solutions from which the minerals precipitate is the basis of analogous applications in medicine and in paleooceanography. In animals with skeletons mineralized with calcium the calcium isotopic composition of soft tissues reflects the relative rate of formation and dissolution of skeletal mineral. In humans changes in the calcium isotopic composition of urine have been shown to be related to changes in bone mineral balance. When the rate of bone formation exceeds the rate of bone resorption, soft tissue <sup>44</sup>Ca/<sup>40</sup>Ca rises. Soft tissue <sup>44</sup>Ca/<sup>40</sup>Ca falls when bone resorption exceeds bone formation. Because of this relationship, calcium isotopic measurements of urine or blood may be useful in the early detection of metabolic bone diseases like [[osteoporosis]].<ref>{{cite journal|last1=Skulan|first1=J|title=Natural calcium isotopic composition of urine as a marker of bone mineral balance|pmid=17463176|journal=Clinical Chemistry|year=2007|volume=653|pages=1155–1158|last2=Bullen|first2=T|last3=Anbar|first3=AD|last4=Puzas|first4=JE|last5=Shackelford|first5=L|last6=Leblanc|first6=A|last7=Smith|first7=SM|issue=6|doi=10.1373/clinchem.2006.080143}}</ref>

A similar system exists in the ocean, where seawater <sup>44</sup>Ca/<sup>40</sup>Ca tends to rise when the rate of removal of Ca<sup>2+</sup> from seawater by mineral precipitation exceeds the input of new calcium into the ocean, and fall when calcium input exceeds mineral precipitation. It follows that rising <sup>44</sup>Ca/<sup>40</sup>Ca corresponds to falling seawater Ca<sup>2+</sup> concentration, and falling <sup>44</sup>Ca/<sup>40</sup>Ca corresponds to rising seawater Ca<sup>2+</sup> concentration. In 1997 Skulan and DePaolo presented the first evidence of change in seawater <sup>44</sup>Ca/<sup>40</sup>Ca over geologic time, along with a theoretical explanation of these changes. More recent papers have confirmed this observation, demonstrating that seawater Ca<sup>2+</sup> concentration is not constant, and that the ocean probably never is in “steady state” with respect to its calcium input and output.<ref>{{cite journal|last1=Fantle|first1=M|last2=DePaolo|first2=D|title=Ca isotopes in carbonate sediment and pore fluid from ODP Site 807A: The Ca2+(aq)–calcite equilibrium fractionation factor and calcite recrystallization rates in Pleistocene sediments|journal=Geochim Cosmochim Acta|year=2007|volume=71|pages=2524–2546|doi=10.1016/j.gca.2007.03.006}}</ref><ref>{{cite journal|last1=Griffith|first1=Elizabeth M.|title=A Dynamic marine calcium cycle during the past 28 million years|pmid=17463176|journal=Science|year=2008|volume=322|pages=1671–1674|last2= Paytan |first2= Adina |last3= Caldeira |first3= Ken|last4= Bullen |first4= Thomas last5= Thomas |first5= Ellen |issue=12|doi=10.1126/science.1163614|last5=Shackelford|last6=Leblanc|first6=A|last7=Smith|first7=SM}}</ref> This has important climatological implications, as the marine calcium cycle is closely tied to the [[carbon cycle]] (see below).

==Geochemical cycling==
Calcium provides an important link between [[tectonics]], [[climate]] and the [[carbon cycle]]. In the simplest terms, uplift of mountains exposes Ca-bearing rocks to chemical weathering and releases Ca<sup>2+</sup> into surface water. This Ca<sup>2+</sup> eventually is transported to the ocean where it reacts with dissolved CO<sub>2</sub> to form [[limestone]]. Some of this limestone settles to the sea floor where it is incorporated into new rocks. Dissolved CO<sub>2</sub>, along with [[carbonate]] and [[bicarbonate]] ions, are referred to as [[Total inorganic carbon|dissolved inorganic carbon]] (DIC).

[[Image:Pamukkale Hierapolis Travertine pools.JPG|thumb| right| Travertine terraces [[Pamukkale]], Turkey]]

The actual reaction is more complicated and involves the bicarbonate ion (HCO<sub>3</sub><sup>-</sup>) that forms when CO<sub>2</sub> reacts with water at seawater [[pH]]:

: {{chem|Ca|2+}} + 2{{chem|HCO|3|-}} → {{chem|CaCO|3}} (limestone) + {{chem|CO|2}} + {{chem|H|2|O}}

Note that at ocean pH most of the CO<sub>2</sub> produced in this reaction is immediately converted back into HCO3<sup>&minus;</sup>. The reaction results in a net transport of one molecule of CO<sub>2</sub> from the ocean/atmosphere into the [[lithosphere]].<ref>{{cite web
|author= Zeebe
|year=2006
|url = http://www.eoearth.org/article/Marine_carbonate_chemistry
|title = Marine carbonate chemistry
|publisher = National Council for Science and the Environment
|accessdate = 2010-03-13}}</ref>

The result is that each Ca<sup>2+</sup> ion released by chemical weathering ultimately removes one CO<sub>2</sub> molecule from the surficial system (atmosphere, ocean, soils and living organisms), storing it in carbonate rocks where it is likely to stay for hundreds of millions of years. The weathering of calcium from rocks thus scrubs CO<sub>2</sub> from the ocean and atmosphere, exerting a strong long-term effect on climate.<ref>{{cite journal|last1=Berner|first1=Robert|title= The long-term carbon cycle, fossil fuels and atmospheric composition |journal=Nature|year=2003|volume=426|pages= 323–326|doi=10.1038/nature02131|pmid=14628061|issue=6964}}</ref>
Analogous cycles involving magnesium, and to a much smaller extent strontium and barium, have the same effect.

As the weathering of limestone (CaCO<sub>3</sub>) liberates equimolar amounts of Ca<sup>2+</sup> and CO<sub>2</sub>, it has no net effect on the CO<sub>2</sub> content of the atmosphere and ocean. The weathering of [[silicate]] rocks like [[granite]], on the other hand, is a net CO2 sink because it produces abundant Ca<sup>2+</sup> very little CO<sub>2</sub>.

==History==
Calcium ([[Latin]] word {{lang|la|''calcis''}} meaning "lime") was known as early as the first century when the [[Ancient Rome|Ancient Romans]] prepared lime as [[calcium oxide]]. Literature dating back to 975 AD notes that [[plaster of paris]] (calcium sulfate), is useful for setting broken bones. It was not isolated until 1808 in [[England]] when [[Humphry Davy|Sir Humphry Davy]] [[Electrolysis|electrolyzed]] a mixture of lime and [[mercuric oxide]].<ref>Davy, H. (1808) "[http://books.google.com/books?id=gpwEAAAAYAAJ&pg=102#v=onepage&q&f=false Electro-chemical researches on the decomposition of  the earths; with observations on the metals obtained from the alkaline earths, and on the amalgam procured from ammonia]," ''Philosophical Transactions of the Royal Society of London'', vol. 98, pages 333-370.</ref> Davy was trying to isolate calcium; when he heard that Swedish chemist [[Jöns Jakob Berzelius]] and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself. He worked with electrolysis throughout his life and also discovered/isolated [[sodium]], [[potassium]], [[magnesium]], [[boron]] and [[barium]]. Calcium metal was not available in large scale until the beginning of the 20th century.

==Occurrence==

{{see also cat|Calcium minerals}}
Calcium is not naturally found in its elemental state. Calcium occurs most commonly in [[sedimentary rocks]] in the minerals [[calcite]], [[dolomite]] and [[gypsum]]. It also occurs in [[igneous rocks|igneous]] and [[metamorphic rocks]] chiefly in the [[silicate minerals]]: [[plagioclase]], [[amphibole]]s, [[pyroxene]]s and [[garnet]]s

==Applications==
Calcium is used<ref>{{RubberBible86th}}</ref>
*as a [[reducing agent]] in the extraction of other metals, such as [[uranium]], [[zirconium]], and [[thorium]].
*as a deoxidizer, desulfurizer, or decarbonizer for various [[Iron|ferrous]] and nonferrous [[alloy]]s.
*as an alloying agent used in the production of [[aluminium]], [[beryllium]], [[copper]], [[lead]], and [[magnesium]] alloys.
*in the making of [[cement]]s and [[Mortar (masonry)|mortars]] to be used in [[construction]].
*in the making of [[cheese]], where calcium [[ions]] influence the activity of [[rennin]] in bringing about the [[coagulation]] of milk.

{{Unreferenced|date=April 2010}}
===Calcium compounds===
*[[Calcium carbonate]] (CaCO<sub>3</sub>) is used in manufacturing [[cement]] and mortar, [[agricultural lime|lime]], [[limestone]] (usually used in the steel industry) and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in [[toothpastes]], for example.
*[[Calcium hydroxide]] solution (Ca(OH)<sub>2</sub>) (also known as [[limewater]]) is used to detect the presence of carbon dioxide by being bubbled through a solution. It turns cloudy where CO<sub>2</sub> is present.
*[[Calcium arsenate]] (Ca<sub>3</sub>(AsO<sub>4</sub>)<sub>2</sub>) is used in [[insecticide]]s.
*[[Calcium carbide]] (CaC<sub>2</sub>) is used to make [[acetylene]] gas (for use in acetylene [[torch]]es for [[welding]]) and in the manufacturing of [[plastic]]s.
*[[Calcium chloride]] (CaCl<sub>2</sub>) is used in [[ice]] removal and [[dust]] control on dirt roads, in conditioner for [[concrete]], as an additive in canned [[tomato]]es, and to provide body for [[automobile]] [[tire]]s.
*[[Cyclamate|Calcium cyclamate]] (Ca(C<sub>6</sub>H<sub>11</sub>NHSO<sub>3</sub>)<sub>2</sub>) was used as a sweetening agent but is no longer permitted for use because of suspected cancer-causing properties.
*[[Calcium gluconate]] (Ca(C<sub>6</sub>H<sub>11</sub>O<sub>7</sub>)<sub>2</sub>) is used as a [[food additive]] and in [[vitamin]] pills.
*[[Calcium hypochlorite]] (Ca(OCl)<sub>2</sub>) is used as a [[swimming pool]] [[disinfectant]], as a [[bleach]]ing agent, as an ingredient in [[deodorant]], and in [[algaecide]] and [[fungicide]].
*[[Calcium permanganate]] (Ca(MnO<sub>4</sub>)<sub>2</sub>) is used in liquid rocket propellant, [[textile]] production, as a water sterilizing agent and in dental procedures.
*[[Calcium phosphate]] (Ca<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>) is used as a supplement for [[animal]] feed, [[fertilizer]], in commercial production for [[dough]] and [[yeast]] products, in the manufacture of [[glass]], and in dental products.
*[[Calcium phosphide]] (Ca<sub>3</sub>P<sub>2</sub>) is used in [[fireworks]], [[rodenticide]], [[torpedo]]es and [[flare (pyrotechnic)|flare]]s.
*[[Calcium stearate]] (Ca(C<sub>18</sub>H<sub>35</sub>O<sub>2</sub>)<sub>2</sub>) is used in the manufacture of [[wax]] [[crayon]]s, [[cement]]s, certain kinds of [[plastic]]s and [[cosmetics]], as a [[food additive]], in the production of water resistant materials and in the production of [[paint]]s.
*[[Calcium sulfate]] (CaSO<sub>4</sub>·2H<sub>2</sub>O) is used as common blackboard chalk, as well as, in its hemihydrate form better known as Plaster of Paris.
*[[Calcium tungstate]] (CaWO<sub>4</sub>) is used in luminous [[paint]]s, [[fluorescent light]]s and in [[X-ray]] studies.
*[[Hydroxylapatite]] (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH), but is usually written Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub>) makes up seventy percent of [[bone]]. Also carbonated-calcium deficient hydroxylapatite is the main mineral of which [[dental enamel]] and [[dentin]] are comprised.

==Nutrition==
{{Main|Calcium in biology|Calcium metabolism}}

{| class="wikitable" align="right"
|+ Recommended adequate intake by the IOM for calcium:<ref name="DietaryFactSheet">{{cite web|url=http://ods.od.nih.gov/factsheets/calcium.asp |title=Dietary Supplement Fact Sheet: Calcium}}</ref>
|-
! Age
! Calcium (mg/day)
|-
| 0–6 months
| 210
|-
| 7–12 months
| 270
|-
|1–3 years
|500
|-
|4–8 years
|800
|-
|9–18 years
|1300
|-
|19–50 years
|1000
|-
|51+ years
|1200
|}

Calcium is an important component of a [[healthy diet]] and a [[Dietary mineral|mineral]] necessary for life. The [[National Osteoporosis Foundation]] says, "Calcium plays an important role in building stronger, denser bones early in life and keeping bones strong and healthy later in life." Approximately ninety-nine percent of the body's calcium is stored in the bones and teeth.<ref>{{cite web|url=http://www.nof.org/prevention/calcium2.htm |title=Osteoporosis Prevention - Calcium Recommendations}}</ref> The rest of the calcium in the body has other important uses, such as some [[exocytosis]], especially [[chemical synapse#Neurotransmitter release|neurotransmitter release]], and [[muscle contraction]]. In the [[electrical conduction system of the heart]], calcium replaces sodium as the mineral that depolarizes the cell, proliferating the action potential. In cardiac muscle, sodium influx commences an action potential, but during potassium efflux, the cardiac myocyte experiences calcium influx, prolonging the action potential and creating a plateau phase of dynamic equilibrium. Long-term calcium deficiency can lead to rickets and poor blood clotting and in case of a menopausal woman, it can lead to [[osteoporosis]], in which the bone deteriorates and there is an increased risk of fractures. While a lifelong deficit can affect bone and tooth formation, over-retention can cause hypercalcemia (elevated levels of calcium in the blood), impaired kidney function and decreased absorption of other minerals.<ref name="committee">{{cite book|author=Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine |title=Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and fluoride|location= Washington DC|publisher= The National Academies Press|year= 1997|isbn=0309064031}}</ref> High calcium intakes or high calcium absorption were previously thought to contribute to the development of kidney stones. However, a high calcium intake has been associated with a lower risk for kidney stones in more recent research.<ref name="curhan">{{cite journal|pmid=8441427|year=1993|author=Curhan, Gc; Willett, Wc; Rimm, Eb; Stampfer, Mj|title=A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones.|volume=328|issue=12|pages=833–8|journal=The New England journal of medicine|doi=10.1056/NEJM199303253281203}}</ref><ref>{{cite journal |author=Bihl G, Meyers A. |title=Recurrent renal stone disease-advances in pathogenesis and clinical management |journal=Lancet |volume=358 |issue=9282 |pages=651–656 |year=2001 |pmid=11530173 |doi= 10.1016/S0140-6736(01)05782-8}}</ref><ref>{{cite journal |author=Hall WD, Pettinger M, Oberman A |title=Risk factors for kidney stones in older women in the Southern United States |journal=Am J Med Sci |volume=322 |issue=1 |pages=12–18 |year=2001 |pmid=11465241 |doi= 10.1097/00000441-200107000-00003}}</ref> [[Vitamin D]] is needed to absorb calcium.

[[Dairy product]]s, such as milk and cheese, are a well-known source of calcium. Some individuals are allergic to dairy products and even more people, particularly those of non Indo-European descent, are [[Lactose intolerance|lactose-intolerant]], leaving them unable to consume non-fermented dairy products in quantities larger than about half a liter per serving. Others, such as [[vegans]], avoid dairy products for ethical and health reasons. Fortunately, many good sources of calcium exist. These include [[seaweeds]] such as [[kelp]], [[wakame]] and [[hijiki]]; nuts and seeds (like [[almond]]s and [[sesame]]); blackstrap [[molasses]]; [[beans]]; [[orange (fruit)|oranges]]; [[figs]]; [[quinoa]]; [[amaranth]]; [[collard greens]]; [[okra]]; [[rutabaga]]; [[broccoli]]; [[dandelion]] leaves; [[kale]]; and fortified products such as orange juice and [[soy milk]]. Research has found an association between diets high in animal protein and increased urinary calcium loss from the bones.<ref>{{cite journal|pmid=1739864|year=1992|last1=Abelow|first1=BJ|last2=Holford|first2=TR|last3=Insogna|first3=KL|title=Cross-cultural association between dietary animal protein and hip fracture: a hypothesis|volume=50|issue=1|pages=14–8|journal=Calcified tissue international|doi=10.1007/BF00297291}}</ref><ref>{{cite journal|pmid=7205408|year=1981|last1=Hegsted|first1=M|last2=Schuette|first2=SA|last3=Zemel|first3=MB|last4=Linkswiler|first4=HM|title=Urinary calcium and calcium balance in young men as affected by level of protein and phosphorus intake|volume=111|issue=3|pages=553–62|journal=The Journal of nutrition}}</ref><ref>{{cite journal|url=http://jn.nutrition.org/cgi/reprint/120/1/134.pdf|author=Kerstetter JE and Allen LH|title=Dietary protein increases urinary calcium|journal=Journal of Nutrition|volume= 120|year=1990|pages=134|pmid=2406396|issue=1}}</ref> A diet high in fruit, vegetables and cereals was demonstrated to result in greater femoral bone mineral density in older men, in comparison to a range of other diets. Diets high in candy were found to result in lower bone density in both men and women.<ref>{{cite journal|pmid=12081842|year=2002|last1=Tucker|first1=KL|last2=Chen|first2=H|last3=Hannan|first3=MT|last4=Cupples|first4=LA|last5=Wilson|first5=PW|last6=Felson|first6=D|last7=Kiel|first7=DP|title=Bone mineral density and dietary patterns in older adults: the Framingham Osteoporosis Study|volume=76|issue=1|pages=245–52|journal=The American journal of clinical nutrition}}</ref>. An overlooked source of calcium is eggshell, which can be ground into a powder and mixed into food or a glass of water.<ref>{{cite journal |author=Schaafsma, Anne and Beelen, Gerard M|title=Eggshell powder, a comparable or better source of calcium than purified calcium carbonate: piglet studies|journal=Journal of the Science of Food and Agriculture |volume=79 |issue=12 |pages=1596–1600 |year=1999 |doi=10.1002/(SICI)1097-0010(199909)79:12<1596::AID-JSFA406>3.0.CO;2-A }}</ref><ref name="pmid12064336">{{cite journal |author=Schaafsma A, van Doormaal JJ, Muskiet FA, Hofstede GJ, Pakan I, van der Veer E |title=Positive effects of a chicken eggshell powder-enriched vitamin-mineral supplement on femoral neck bone mineral density in healthy late post-menopausal Dutch women |journal=Br. J. Nutr. |volume=87 |issue=3 |pages=267–75 |year=2002 |pmid=12064336 |doi=10.1079/BJNBJN2001515}}</ref><ref name="pmid15018022">{{cite journal |author=Rovenský J, Stancíková M, Masaryk P, Svík K, Istok R |title=Eggshell calcium in the prevention and treatment of osteoporosis |journal=Int J Clin Pharmacol Res |volume=23 |issue=2-3 |pages=83–92 |year=2003 |pmid=15018022}}</ref> Cultivated vegetables generally have less calcium than wild plants.<ref>{{cite web|url=http://www.beyondveg.com/nieft-k/instincto-guide/instincto-guide1e.shtml |title=Original Wild Foods vs. Available Foods Today for Instinctos}}</ref>

The calcium content of most foods can be found in the USDA National Nutrient Database.<ref>{{cite web|url=http://www.nal.usda.gov/fnic/foodcomp/search |title=USDA National Nutrient Database}}</ref>

===Dietary calcium supplements===
[[Image:500 mg calcium supplements with vitamin D.jpg|thumb|500 milligram calcium supplements made from [[calcium carbonate]]]]
Calcium supplements are used to prevent and to treat calcium deficiencies. Most experts recommend that supplements be taken with food and that no more than 600&nbsp;mg should be taken at a time because the percent of calcium absorbed decreases as the amount of calcium in the supplement increases.<ref name="DietaryFactSheet"/> It is recommended to spread doses throughout the day. Recommended daily calcium intake for adults ranges from 1000 to 1500&nbsp;mg. It is recommended to take supplements with food to aid in absorption.

[[Vitamin D]] is added to some calcium supplements. Proper vitamin D status is important because vitamin D is converted to a hormone in the body which then induces the synthesis of intestinal proteins responsible for calcium absorption.<ref>{{cite book|author=Combs, G |title=The Vitamins| page=161|publisher= Academic Press|year= 2008|isbn=0121834905}}</ref>

*The absorption of calcium from most food and commonly used dietary supplements is very similar.<ref name="Weaver">{{cite book|author=Weaver, CM|chapter= Calcium|title= Present Knowledge in Nutrition, 9th Ed|volume =I| page= 377|publisher= ILSI Press|year= 2006}}</ref> This is contrary to what many calcium supplement manufacturers claim in their promotional materials.
*[[Milk]] is an excellent source of dietary calcium for those whose body tolerate it because it has a high concentration of calcium and the calcium in milk is excellently absorbed.<ref name="Weaver"/>
*[[Soymilk]] and other vegetable milks are usually sold with calcium added so that their calcium concentration is as high as in milk
*Also different kind of [[juice]]s boosted with calcium are widely available. 
*[[Calcium carbonate]] is the most common and least expensive calcium supplement. It should be taken with food. It depends on low pH levels for proper absorption in the intestine.<ref>{{cite book
|last = Remington
|first = Joseph
|title = Remington: The Science and Practice of Pharmacy
|publisher = Lippincott Williams & Wilkins
|year = 2005
|pages = 1338
|isbn = 0781746736}}</ref> Some studies suggests that the absorption of calcium from calcium carbonate is similar to the absorption of calcium from milk.<ref>{{cite journal|author=Zhao, Y|title=Calcium bioavailability of calcium carbonate fortified soy milk is equivalent to cow's milk in young women|journal= J. Nutr. |volume=135 |issue=10|page=2379|url=http://jn.nutrition.org/cgi/content/full/135/10/2379|pmid=16177199|year=2005|last2=Martin|first2=BR|last3=Weaver|first3=CM}}</ref><ref>{{cite journal|author=Martini, Ligia and Wood, Richard J|title=Relative bioavailability of calcium-rich dietary sources in the elderly|url=http://www.ajcn.org/cgi/content/abstract/76/6/1345|journal=American Journal of Clinical Nutrition|volume=76 |issue=6|pages=1345–1350|year=2002|pmid=12450902}}</ref> While most people digest calcium carbonate very well, some might develop gastrointestinal discomfort or gas. Taking magnesium with it can help to avoid constipation. Calcium carbonate is 40% elemental calcium. 1000&nbsp;mg will provide 400&nbsp;mg of calcium. However, supplement labels will usually indicate how much calcium is present in each serving, not how much calcium carbonate is present.
*[[Antacids]] frequently contain calcium carbonate, and are a commonly used, inexpensive calcium supplement
*[[Coral Calcium]] is a salt of calcium derived from fossilized coral reefs. Coral calcium is composed of calcium carbonate and trace minerals.
*[[Calcium citrate]] can be taken without food and is the supplement of choice for individuals with achlorhydria or who are taking histamine-2 blockers or proton-pump inhibitors.<ref name = "osgknm">{{cite journal|doi=10.1177/0115426507022003286|title=Calcium Supplementation in Clinical Practice: A Review of Forms, Doses, and Indications|year=2007|author=Straub, D. A.|journal=Nutrition in Clinical Practice|volume=22|pages=286|pmid=17507729|issue=3}}</ref> It is more easily digested and absorbed than calcium carbonate if taken on an empty stomach and less likely to cause constipation and gas than calcium carbonate. It also has a lower risk of contributing to the formation of kidney stones. Calcium citrate is about 21% elemental calcium. 1000&nbsp;mg will provide 210&nbsp;mg of calcium. It is more expensive than calcium carbonate and more of it must be taken to get the same amount of calcium.
*[[Calcium phosphate]] costs more than calcium carbonate, but less than calcium citrate. It is easily absorbed and is less likely to cause constipation and gas than either.
*[[Calcium lactate]] has similar absorption as calcium carbonate<ref>{{cite journal|doi=10.1021/jf020065g|title=Calcium Absorption from Three Salts and CaSO<sub>4</sub>-Fortified Bread in Premenopausal Women|year=2002|author=Martin, Berdine R.|journal=Journal of Agricultural and Food Chemistry|volume=50|pages=3874|pmid=12059174|last2=Weaver|first2=CM|last3=Heaney|first3=RP|last4=Packard|first4=PT|last5=Smith|first5=DL|issue=13}}</ref>, but is more expensive. Calcium lactate and calcium gluconate are less concentrated forms of calcium and are not practical oral supplements.<ref name = "osgknm"/>
*Calcium [[chelates]] are synthetic calcium compounds, with calcium bound to an organic molecule, such as malate, aspartate, or fumarate. These forms of calcium may be better absorbed on an empty stomach. However, in general they are absorbed similarly to calcium carbonate and other common calcium supplements when taken with food.<ref>{{cite journal|doi=10.1021/jf0200422|title=Absorption of Calcium Fumarate Salts Is Equivalent to Other Calcium Salts When Measured in the Rat Model|year=2002|author=Weaver, Connie M.|journal=Journal of Agricultural and Food Chemistry|volume=50|pages=4974|pmid=12166992|last2=Martin|first2=BR|last3=Costa|first3=NM|last4=Saleeb|first4=FZ|last5=Huth|first5=PJ|issue=17}}</ref> The 'chelate' mimics the action that natural food performs by keeping the calcium soluble in the intestine. Thus, on an empty stomach, in some individuals, chelates might theoretically be absorbed better.
*[[Hydroxylapatite#Supplement|Microcrystalline hydroxyapatite]] (MH) is marketed as a calcium supplement, and has in some randomized trials been found to be more effective than calcium carbonate.

In July 2006, a report citing research from [[Fred Hutchinson Cancer Research Center]] in Seattle, Washington claimed that women in their 50s gained 5 pounds less in a period of 10 years by taking more than 500&nbsp;mg of calcium supplements than those who did not. However, the doctor in charge of the study, Dr. Alejandro J. Gonzalez also noted it would be "going out on a limb" to suggest calcium supplements as a weight-limiting aid.<ref name="WeightSupplements">{{cite web|title=
Calcium May Help With Weight Loss|accessdate=2007-07-10|url=http://www.rxalternativemedicine.com/headlines_news.php#headline77|author=Harding, Anne}}</ref>

===Prevention of fractures due to osteoporosis===
Such studies often do not test calcium alone, but rather combinations of calcium and vitamin D. [[Randomized controlled trials]] found both positive<ref name="pmid9278463">{{cite journal |author=Dawson-Hughes B, Harris SS, Krall EA, Dallal GE |title=Effect of calcium and vitamin D supplementation on bone density in men and women 65 years of age or older |journal=N. Engl. J. Med. |volume=337 |issue=10 |pages=670–6 |year=1997 |pmid=9278463 |doi=10.1056/NEJM199709043371003}}</ref><ref name = "pmid16034903"/> and negative<ref name="pmid16481635">{{cite journal |author=Jackson RD, LaCroix AZ, Gass M |title=Calcium plus vitamin D supplementation and the risk of fractures |journal=N. Engl. J. Med. |volume=354 |issue=7 |pages=669–83 |year=2006 |pmid=16481635 |doi=10.1056/NEJMoa055218}}</ref><ref name="pmid15885294">{{cite journal |author=Grant AM, Avenell A, Campbell MK |title=Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (Randomised Evaluation of Calcium Or vitamin D, RECORD): a randomised placebo-controlled trial |journal=Lancet |volume=365 |issue=9471 |pages=1621–8 |year=2005 |pmid=15885294 |doi=10.1016/S0140-6736(05)63013-9}}</ref><ref name="pmid15860827">{{cite journal |author=Porthouse J, Cockayne S, King C |title=Randomised controlled trial of calcium and supplementation with cholecalciferol (vitamin D3) for prevention of fractures in primary care |journal=BMJ |volume=330 |issue=7498 |pages=1003 |year=2005 |pmid=15860827 |doi=10.1136/bmj.330.7498.1003 |pmc=557150}}</ref><ref name="pmid16636212">{{cite journal |author=Prince RL, Devine A, Dhaliwal SS, Dick IM |title=Effects of calcium supplementation on clinical fracture and bone structure: results of a 5-year, double-blind, placebo-controlled trial in elderly women |journal=Arch. Intern. Med. |volume=166 |issue=8 |pages=869–75 |year=2006 |pmid=16636212 |doi=10.1001/archinte.166.8.869}}</ref> effects. The different results may be explained by doses of calcium and underlying rates of calcium supplementation in the control groups.<ref name="pmid16813354">{{cite journal |author=Fletcher RH |title=Calcium plus vitamin D did not prevent hip fracture or colorectal cancer in postmenopausal women |journal=ACP J. Club |volume=145 |issue=1 |pages=4–5 |year=2006 |pmid=16813354|url=http://www.acpjc.org/Content/145/1/issue/ACPJC-2006-145-1-004.htm |format=subscription required}}</ref> However, it is clear that increasing the intake of calcium promotes deposition of calcium in the bones, where it is of more benefit in preventing the compression fractures resulting from the osteoporotic thinning of the [[dendritic]] web of the bodies of the vertebrae, than it is at preventing the more serious cortical bone fractures which happen at hip and wrist.{{Citation needed|date=January 2010}}

===Possible cancer prevention===
A [[meta-analysis]]<ref name="pmid16034903">{{cite journal |author=Weingarten MA, Zalmanovici A, Yaphe J |title=Dietary calcium supplementation for preventing colorectal cancer, adenomatous polyps and calcium metabolisism disorder. |journal=Cochrane database of systematic reviews (Online) |issue=3 |pages=CD003548 |year=2005 |pmid=16034903 |doi=10.1002/14651858.CD003548.pub3}}</ref> by the international [[Cochrane Collaboration]] of two [[randomized controlled trials]]<ref name="pmid9887161">{{cite journal |author=Baron JA, Beach M, Mandel JS |title=Calcium supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group |journal=N. Engl. J. Med. |volume=340 |issue=2 |pages=101–7 |year=1999 |pmid=9887161 |doi=10.1056/NEJM199901143400204}}</ref><ref name="pmid11073017">{{cite journal |author=Bonithon-Kopp C, Kronborg O, Giacosa A, Räth U, Faivre J |title=Calcium and fibre supplementation in prevention of colorectal adenoma recurrence: a randomised intervention trial. European Cancer Prevention Organisation Study Group |journal=Lancet |volume=356 |issue=9238 |pages=1300–6 |year=2000 |pmid=11073017 |doi=10.1016/S0140-6736(00)02813-0}}</ref> found that calcium "might contribute to a moderate degree to the prevention of adenomatous [[colonic polyps]]".

More recent studies were conflicting, and one which was positive for effect (Lappe, et al.) did control for a possible anti-carcinogenic effect of [[vitamin D]], which was found to be an independent positive influence from calcium-alone on cancer risk (see second study below) <ref>{{cite journal|pmid=17556697|year=2007|author=Lappe, Jm; Travers-Gustafson, D; Davies, Km; Recker, Rr; Heaney, Rp|title=Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial|volume=85|issue=6|pages=1586–91|journal=The American journal of clinical nutrition|format=Free full text}}</ref>.
*A [[randomized controlled trial]] found that 1000&nbsp;mg of elemental calcium and 400 IU of vitamin D<sub>3</sub> had no effect on colorectal cancer<ref name="pmid16481636">{{cite journal |author=Wactawski-Wende J, Kotchen JM, Anderson GL |title=Calcium plus vitamin D supplementation and the risk of colorectal cancer |journal=N. Engl. J. Med. |volume=354 |issue=7 |pages=684–96 |year=2006 |pmid=16481636 |doi=10.1056/NEJMoa055222}}</ref>
*A [[randomized controlled trial]] found that 1400–1500&nbsp;mg supplemental calcium and 1100 IU vitamin D<sub>3</sub> reduced aggregated cancers with a [[relative risk]] of 0.402.<ref name="pmid17556697">{{cite journal |author=Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP |title=Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial |journal=Am. J. Clin. Nutr. |volume=85 |issue=6 |pages=1586–91 |year=2007 |pmid=17556697}}</ref>
*An observational [[cohort study]] found that high calcium and vitamin D intake was associated with "lower risk of developing premenopausal breast cancer."<ref name="pmid17533208">{{cite journal |author=Lin J, [[JoAnn E. Manson|Manson JE]], Lee IM, Cook NR, Buring JE, Zhang SM |title=Intakes of calcium and vitamin d and breast cancer risk in women |journal=Arch. Intern. Med. |volume=167 |issue=10 |pages=1050–9 |year=2007 |pmid=17533208 |doi=10.1001/archinte.167.10.1050}}</ref>

===Hazards and Toxicity===
Compared to other metals, the calcium ion and most calcium compounds have low toxicity. This is not surprising given the very high natural abundance of calcium compounds in the environment and in organisms. Calcium poses few, if any, serious environmental problems. Acute calcium poisoning is rare, and difficult to achieve unless calcium compounds are administered intravenously. For example, the oral [[median lethal dose]] (LD<sup>50</sub>) for rats for [[calcium carbonate]] and [[calcium chloride]] are 6.45 <ref>{{Cite book |last= Lewis |first= R. J. |year= 1996 |title= Sax's Dangerous Properties of Industrial Materials|edition= 9|publisher= Van Nostrand Reinhold |location= New York, NY |page= 635 |isbn= 0471378585}}</ref> and 1.4&nbsp;g/kg,<ref>{{Cite book
 |title = ITII. Toxic and Hazardous Industrial Chemicals Safety Manual
 |publisher = The International Technical Information Institute
 |year =1988
 |location = Tokyo, Japan
 |page = 101}}</ref> respectively.

Calcium metal is hazardous because of its sometimes violent reactions with water and acids. Calcium metal is found in some drain cleaners, where it functions to generate heat and [[calcium hydroxide]] that [[Saponification|saponifies]] the fats and liquefies the proteins (e.g., hair) that block drains. When swallowed calcium metal has the same effect on the mouth, esophagus and stomach, and can be fatal.<ref>Rumack BH. POISINDEX. Information System Micromedex, Inc., Englewood, CO, 2010; CCIS Volume 143. Hall AH and Rumack BH (Eds)</ref>

Excessive consumption of calcium carbonate antacids/dietary supplements (such as Tums) over a period of weeks or months can cause [[milk-alkali syndrome]], with symptoms ranging from [[hypercalcemia]] to potentially fatal [[renal failure]]. What constitutes “excessive” consumption is not well known and probably varies a great deal from person to person. Persons who consume more than 10&nbsp;grams/day of CaCO<sub>3</sub> (=4 g Ca) are at risk of developing milk-alkali syndrome,<ref>{{cite journal |author=Beall DP, Henslee HB, Webb HR, Scofield RH |title=Milk-alkali syndrome: a historical review and description of the modern version of the syndrome |journal=Am. J. Med. Sci. |volume=331 |issue=5 |pages=233–42 |year=2006|pmid=16702792 |doi= 10.1097/00000441-200605000-00001|url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00000441-200605000-00001}}</ref> but the condition has been reported in at least one person consuming only 2.5&nbsp;grams/day of CaCO<sub>3</sub> (=1 g Ca), an amount usually considered moderate and safe.<ref>{{cite journal |author= Picolos MK and Orlander PR |title=Calcium carbonate toxicity: The updated milk-alkali syndrome; report of 3 cases and review of the literature|journal=Endocrine Practice |volume=4 |issue=11 |pages=272–80 |year=2005}}</ref>

==See also==
*[[Calcium metabolism]]
*[[Calcium in biology]]
*[[:Category:Calcium compounds|Calcium compounds]]
*[[Disorders of calcium metabolism]]

==References==
{{Reflist|2}}

==Further reading==
*Rebecca J. Donatelle. Health, The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.

==External links==
{{Commons|Calcium}}
{{Wiktionary|calcium}}
*[http://www.webelements.com/webelements/elements/text/Ca/index.html WebElements.com — Calcium]
*[http://www.nal.usda.gov/fnic/foodcomp/Data/SR17/wtrank/sr17a301.pdf USDA National Nutrient Database, Calcium content of selected foods]
*[http://www.eatwell.gov.uk/healthydiet/nutritionessentials/vitaminsandminerals/calcium/ UK Food Standards Agency: Calcium]
*[http://ods.od.nih.gov/factsheets/calcium.asp Nutrition fact sheet from the National Institutes of Health]

{{Clear}}
{{Compact periodic table}}
{{Calcium compounds}}

[[Category:Alkaline earth metals]]
[[Category:Calcium|*]]
[[Category:Chemical elements]]
[[Category:Dietary minerals]]
[[Category:Dietary supplements]]
[[Category:Reducing agents]]

[[af:Kalsium]]
[[ar:كالسيوم]]
[[ast:Calciu]]
[[az:Kalsium]]
[[bn:ক্যালসিয়াম]]
[[zh-min-nan:Ca (goân-sò͘)]]
[[bs:Kalcijum]]
[[bg:Калций]]
[[ca:Calci]]
[[cv:Кальци]]
[[cs:Vápník]]
[[co:Calciu]]
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[[dv:ކެލްސިއަމް]]
[[nv:Káálsiiyin]]
[[et:Kaltsium]]
[[el:Ασβέστιο]]
[[es:Calcio]]
[[eo:Kalcio]]
[[eu:Kaltzio]]
[[fa:کلسیم]]
[[fr:Calcium]]
[[frr:Kaltsium]]
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[[gl:Calcio]]
[[hak:Koi]]
[[xal:Калцион]]
[[ko:칼슘]]
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[[hy:Կալցիում]]
[[hi:कैल्शियम]]
[[hr:Kalcij]]
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[[is:Kalsín]]
[[it:Calcio (elemento)]]
[[he:סידן]]
[[kn:ಕ್ಯಾಲ್ಶಿಯಮ್]]
[[ka:კალციუმი]]
[[sw:Kalisi]]
[[ht:Kalsyòm]]
[[ku:Kalsiyûm]]
[[la:Calcium]]
[[lv:Kalcijs]]
[[lb:Kalzium]]
[[lt:Kalcis]]
[[lij:Cäso (metallo)]]
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[[hu:Kalcium]]
[[mk:Калциум]]
[[ml:കാൽ‌സ്യം]]
[[mi:Konupūmā]]
[[mr:कॅल्शियम]]
[[ms:Kalsium]]
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[[nah:Tenextepoztli]]
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[[ja:カルシウム]]
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[[nds:Calcium]]
[[pl:Wapń]]
[[pt:Cálcio]]
[[ro:Calciu]]
[[qu:Isku q'illay]]
[[ru:Кальций]]
[[sah:Калсиум]]
[[stq:Calcium]]
[[sq:Kalciumi]]
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[[sk:Vápnik]]
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[[sr:Калцијум]]
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[[tl:Kalsyo]]
[[ta:கல்சியம்]]
[[te:కాల్షియమ్]]
[[th:แคลเซียม]]
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[[Category:2Fix]]