View source for Magnesium carbonate

{{Use dmy dates|date=April 2021}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 462096540
| Name = Magnesium carbonate
| ImageFile=Magnesium carbonate.svg
| ImageSize=120px
| ImageClass = skin-invert
| ImageFile1 = Magnesite-xtal-packing-a-3D-bs-17.png
| ImageFile2=Uhličitan hořečnatý.PNG
| OtherNames = [[Magnesite]]<br/>Barringtonite (dihydrate)<br/>Nesequehonite (trihydrate)<br/>[[Lansfordite]] (pentahydrate)
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10563
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1200736
| InChI = 1/CH2O3.Mg/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
| InChIKey = ZLNQQNXFFQJAID-NUQVWONBAU
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 31793
| SMILES = [Mg+2].[O-]C([O-])=O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/CH2O3.Mg/c2-1(3)4;/h(H2,2,3,4);/q;+2/p-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = ZLNQQNXFFQJAID-UHFFFAOYSA-L
| CASNo = 546-93-0
| CASNo_Comment = (anhydrous)
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo2 = 17968-26-2
| CASNo2_Comment = (monohydrate)
| CASNo3_Ref = {{cascite|changed|??}}
| CASNo3 = 5145-48-2
| CASNo3_Comment = (dihydrate)
| CASNo4_Ref = {{cascite|changed|??}}
| CASNo4 = 14457-83-1
| CASNo4_Comment = (trihydrate)
| CASNo5_Ref = {{cascite|changed|??}}
| CASNo5 = 61042-72-6
| CASNo5_Comment = (pentahydrate)
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 0IHC698356
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = 0E53J927NA
| UNII1_Comment = (monohydrate)

| PubChem = 11029
| RTECS = OM2470000
  }}
|Section2={{Chembox Properties
| MolarMass = 84.3139 g/mol (anhydrous)
| Formula = {{chem2|MgCO3}}
| Appearance = Colourless crystals or white solid<br /> [[Hygroscopic]]
| Odor = Odorless
| Density = 2.958 g/cm<sup>3</sup> (anhydrous) <br /> 2.825 g/cm<sup>3</sup> (dihydrate) <br /> 1.837 g/cm<sup>3</sup> (trihydrate) <br /> 1.73 g/cm<sup>3</sup> (pentahydrate)
| Solubility = Anhydrous:<br /> 0.0139 g/100{{nnbsp}}ml (25 °C)<br /> 0.0063 g/100{{nnbsp}}ml (100 °C)<ref name=chemister />
| SolubilityProduct = 10<sup>−7.8</sup><ref>{{cite journal |first1= Pascale |last1= Bénézeth |first2= Giuseppe D. |last2= Saldi |first3= Jean-Louis |last3= Dandurand |first4= Jacques |last4= Schott |title= Experimental determination of the solubility product of magnesite at 50 to 200&nbsp;°C |journal= Chemical Geology |volume= 286 |issue=1–2 |year= 2011 |pages= 21–31 |doi= 10.1016/j.chemgeo.2011.04.016 |bibcode= 2011ChGeo.286...21B }}</ref>
| SolubleOther = Soluble in acid, aqueous [[carbon dioxide|{{chem2|CO2}}]] <br /> Insoluble in [[acetone]], [[ammonia]]
| MeltingPtC = 350
| MeltingPt_notes = <br /> decomposes (anhydrous)<br /> {{convert|165|C|F K}}<br /> (trihydrate)
| RefractIndex = 1.717 (anhydrous)<br /> 1.458 (dihydrate)<br /> 1.412 (trihydrate) 
| MagSus = −32.4·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
|Section3={{Chembox Structure
| Coordination = 
| CrystalStruct = [[Hexagonal crystal family#Trigonal crystal system|Trigonal]]
| SpaceGroup = [[List of space groups#List of trigonal|R{{overline|3}}c, No. 167]]<ref name="Ross" />
}}
|Section5={{Chembox Thermochemistry
| DeltaHf = −1113 kJ/mol<ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A22}}</ref>
| Entropy = 65.7 J/mol·K<ref name=chemister>{{Cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=634|title=Magnesium carbonate}}</ref><ref name=b1/>
| DeltaGf = −1029.3 kJ/mol<ref name=chemister />
| HeatCapacity = 75.6 J/mol·K<ref name=chemister />
 }}
|Section6={{Chembox Pharmacology
| ATCCode_prefix = A02
| ATCCode_suffix = AA01
| ATC_Supplemental = {{ATC|A06|AD01}}
}}
|Section7={{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0969.htm ICSC 0969]
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S = 
| FlashPt = Non-flammable
| PEL = {{ubl
 | TWA 15 mg/m<sup>3</sup> (total)
 | TWA 5 mg/m<sup>3</sup> (resp)<ref>{{PGCH|0373}}</ref>
 }}
  }}
|Section8={{Chembox Related
| OtherAnions = [[Magnesium bicarbonate]]
| OtherCations = [[Beryllium carbonate]]<br/>[[Calcium carbonate]]<br/>[[Strontium carbonate]]<br/>[[Barium carbonate]]<br/>[[Radium carbonate]]
| OtherCompounds = [[Artinite]]<br/>[[Hydromagnesite]]<br/>[[Dypingite]]
  }}
}}

{{Expand German|topic=sci|date=December 2018}}

'''Magnesium carbonate''', {{chem2|[[Magnesium|Mg]][[Carbonate|CO3]]}} (archaic name [[magnesia alba]]), is an inorganic salt that is a colourless or white solid. Several [[hydrate]]d and [[Base (chemistry)|basic]] forms of magnesium carbonate also exist as [[mineral]]s.

==Forms==
The most common magnesium carbonate forms are the [[anhydrous]] salt called [[magnesite]] ({{chem2|MgCO3}}), and the di, tri, and pentahydrates known as barringtonite ({{chem2|MgCO3*2H2O}}), nesquehonite ({{chem2|MgCO3*3H2O}}), and lansfordite ({{chem2|MgCO3*5H2O}}), respectively.<ref name = ullmann/> Some basic forms such as [[artinite]] ({{chem2|Mg2CO3(OH)2*3H2O}}), [[hydromagnesite]] ({{chem2|Mg5(CO3)4(OH)2*4H2O}}), and [[dypingite]] ({{chem2|Mg5(CO3)4(OH)2*5H2O}}) also occur as [[minerals]]. All of those minerals are colourless or white.

Magnesite consists of colourless or white [[trigonal]] [[crystals]]. The anhydrous salt is practically [[insoluble]] in [[water]], [[acetone]], and [[ammonia]]. All forms of magnesium carbonate react with [[acids]]. Magnesite crystallizes in the [[calcite]] structure wherein [[magnesium|{{chem2|Mg(2+)}}]] is [[Coordination geometry#Crystallography usage|surrounded by]] six [[oxygen]] atoms.<ref name="Ross">{{ cite journal | title = The equation of state and high-pressure behavior of magnesite | first1 = Nancy L. | last1 = Ross | journal = [[American Mineralogist|Am. Mineral.]] | year = 1997 | volume = 82 | issue = 7–8 | pages = 682–688 | doi = 10.2138/am-1997-7-805 | bibcode = 1997AmMin..82..682R | s2cid = 43668770 }}</ref>

{| class="wikitable" style="margin:1em auto; text-align:center;"
|+Crystal structure of magnesium carbonate
|-
! Carbonate coordination
! Magnesium coordination
! Unit cell
|-
| [[File:Carbonate-coordination-in-magnesite-3D-bs-17.png|125px]]
| [[File:Magnesium-coordination-in-magnesite-3D-bs-17.png|125px]]
| [[File:Magnesite-unit-cell-3D-bs-17.png|250px]]
|}

The dihydrate has a [[triclinic]] structure, while the trihydrate has a [[monoclinic]] structure.

References to "light" and "heavy" magnesium carbonates actually refer to the magnesium hydroxy carbonates [[hydromagnesite]] and [[dypingite]], respectively.<ref>{{cite journal|doi=10.1016/S0304-386X(01)00197-9|title=Preparation of a magnesium hydroxy carbonate from magnesium hydroxide | year=2001 | last1=Botha | first1=A. | last2=Strydom | first2=C.A. | journal=Hydrometallurgy | volume=62 | issue=3 | pages=175|bibcode=2001HydMe..62..175B }}</ref> The "light" form is precipitated from magnesium solutions using alkali carbonate at "normal temperatures" while the "heavy" may be produced from boiling concentrated solutions followed by precipitation to dryness, washing of the precipitate, and drying at 100 C.<ref>{{cite book|title=General and inorganic chemistry, 2nd ed. | year=1951 | author= J.R. Partington}}</ref>

==Preparation==

Magnesium carbonate is ordinarily obtained by mining the mineral [[magnesite]]. Seventy percent of the world's supply is mined and prepared in China.<ref name=Alf>{{cite web |title=The Hidden Environmental Cost of Climbing Chalk |url=https://www.climbing.com/gear/the-hidden-environmental-cost-of-climbing-chalk/ |last=Allf |first=Bradley |date=2018-05-21 |website=[[Climbing Magazine]] |publisher=Cruz Bay Publishing |access-date=2018-05-22 |quote=In fact, China produces 70 percent of the world’s magnesite. Most of that production—both mining and processing—is concentrated in a small corner of Liaoning, a hilly industrial province in northeast China between Beijing and North Korea.}}</ref>

Magnesium carbonate can be prepared in laboratory by reaction between any soluble magnesium salt and [[sodium bicarbonate]]:
:{{awrap|MgCl<sub>2</sub>(aq)&nbsp;+ 2&nbsp;NaHCO<sub>3</sub>(aq)&nbsp;→}} {{awrap|MgCO<sub>3</sub>(s)&nbsp;+ 2&nbsp;NaCl(aq)&nbsp;+ H<sub>2</sub>O(l)&nbsp;+ CO<sub>2</sub>(g)}}

If magnesium chloride (or sulfate) is treated with aqueous sodium carbonate, a precipitate of basic magnesium carbonate – a [[hydrate]]d complex of magnesium carbonate and [[magnesium hydroxide]] – rather than magnesium carbonate itself is formed:
:{{awrap|5 MgCl<sub>2</sub>(aq)&nbsp;+ 5&nbsp;Na<sub>2</sub>CO<sub>3</sub>(aq)&nbsp;+ 5&nbsp;H<sub>2</sub>O(l)&nbsp;→}} {{awrap|Mg<sub>4</sub>(CO<sub>3</sub>)<sub>3</sub>(OH)<sub>2</sub>·3H<sub>2</sub>O(s)&nbsp;+ Mg(HCO<sub>3</sub>)<sub>2</sub>(aq)&nbsp;+ 10&nbsp;NaCl(aq)}}

High purity industrial routes include a path through [[magnesium bicarbonate]], which can be formed by combining a [[slurry]] of magnesium hydroxide and [[carbon dioxide]] at high pressure and moderate temperature.<ref name = ullmann>{{Ullmann | title = Magnesium Compounds | author1 = Margarete Seeger | author2 = Walter Otto | author3 = Wilhelm Flick | author4 = Friedrich Bickelhaupt | author5 = Otto S. Akkerman | doi = 10.1002/14356007.a15_595.pub2}}</ref> The bicarbonate is then vacuum dried, causing it to lose carbon dioxide and a molecule of water:
:{{chem2|Mg(OH)2 + 2 CO2 → Mg(HCO3)2}}
:{{chem2|Mg(HCO3)2 → MgCO3 + CO2 + H2O}}

==Chemical properties==

===With acids===
Like many common group 2 metal carbonates, magnesium carbonate reacts with aqueous acids to release [[carbon dioxide]] and [[water]]:
:{{chem2|MgCO3 + 2 HCl → MgCl2 + CO2 + H2O}}
:{{chem2|MgCO3 + H2SO4 → MgSO4 + CO2 + H2O}}

===Decomposition===
At high temperatures MgCO<sub>3</sub> decomposes to [[magnesium oxide]] and [[carbon dioxide]]. This process is important in the production of magnesium oxide.<ref name = ullmann/> This process is called [[calcining]]:
:{{chem2|MgCO3 → MgO + CO2}} (ΔH = +118 kJ/mol)

The decomposition temperature is given as 350&nbsp;°C (662&nbsp;°F).<ref>{{cite web|url=http://avogadro.chem.iastate.edu/MSDS/MgCO3_anhydrous.htm|title=IAState MSDS|access-date=4 May 2013|archive-date=25 April 2016|archive-url=https://web.archive.org/web/20160425225832/http://avogadro.chem.iastate.edu/MSDS/MgCO3_anhydrous.htm|url-status=dead}}</ref><ref>{{cite book |author= Weast, Robert C.|title=CRC Handbook of Chemistry and Physics |url= https://archive.org/details/crchandbookofche00clev|url-access= registration|edition=59th |year=1978 |publisher=CRC Press |location=West Palm Beach, FL |id={{Listed Invalid ISBN|0-8493-0549-8}}|page=B-133 |display-authors=etal}}</ref>
However, calcination to the oxide is generally not considered complete below 900&nbsp;°C due to interfering readsorption of liberated carbon dioxide.

The hydrates of the salts lose water at different temperatures during decomposition.<ref name=Open>{{cite web|url=http://core.kmi.open.ac.uk/download/pdf/10883918.pdf|title=Conventional and Controlled Rate Thermal analysis of nesquehonite Mg(HCO<sub>3</sub>)(OH)·2(H<sub>2</sub>O)}}</ref> For example, in the trihydrate {{chem2|MgCO3*3H2O}}, which molecular formula may be written as {{chem2|Mg(HCO3)(OH)*2H2O}}, the dehydration steps occur at 157&nbsp;°C and 179&nbsp;°C as follows:<ref name=Open />

:{{chem2|Mg(HCO3)(OH)*2(H2O) → Mg(HCO3)(OH)*(H2O) + H2O}} at 157 °C
:{{chem2|Mg(HCO3)(OH)*(H2O) → Mg(HCO3)(OH) + H2O}} at 179 °C

==Uses==
The primary use of magnesium carbonate is the production of [[magnesium oxide]] by [[calcining]]. Magnesite and [[Dolomite (mineral)|dolomite]] minerals are used to produce [[refractory brick]]s.<ref name = ullmann/> {{chem2|MgCO3}} is also used in [[flooring]], [[fireproofing]], [[Fire extinguisher#Types of extinguishing agents|fire extinguishing compositions]], [[cosmetics]], [[dusting powder]], and [[toothpaste]]. Other applications are as [[Filler (materials)|filler material]], smoke suppressant in plastics, a reinforcing agent in [[neoprene]] rubber, a [[Desiccant|drying agent]], and colour retention in foods.

Because of its low solubility in water and [[hygroscopy|hygroscopic]] properties, {{chem2|MgCO3}} was first added to [[table salt]] ({{chem2|NaCl}}) in 1911 to make it flow more freely. The [[Morton Salt]] company adopted the slogan "When it rains it pours", highlighting that its salt, which contained {{chem2|MgCO3}}, would not stick together in humid weather.<ref>{{cite web |title=Her Debut - Morton Salt |url=http://www.mortonsalt.com/heritage-era/her-first-appearance/ |access-date = 2017-12-27 }}</ref> 

[[File:Hojer jan 0429.JPG|thumb|Climber [[Jan Hojer]] blows surplus ''chalk'' from his hand. Boulder World Cup 2015]]
Powdered magnesium carbonate, known as ''climbing chalk'' or ''gym chalk'' is also used as a drying agent on athletes' hands in [[rock climbing]], [[gymnastics]], powerlifting, [[Olympic weightlifting|weightlifting]] and other sports in which a firm grip is necessary.<ref name=Alf />  A variant is [[liquid chalk]] and another is [[mesoporous magnesium carbonate]].

Recent developments in sports chalk manufacturing have explored the differences between naturally mined and laboratory-synthesized forms of magnesium carbonate. Laboratory-produced MgCO<sub>3</sub> is created through controlled precipitation of purified magnesium salts and carbonate compounds, producing higher-purity material with fewer mineral impurities than mined magnesite.<ref name="USDA2023">{{cite report
 |title=Technical Evaluation Report: Magnesium Carbonate and Magnesium Carbonate Hydroxide Handling/Processing
 |publisher=U.S. Department of Agriculture – Agricultural Marketing Service
 |date=December 2023
 |url=https://www.ams.usda.gov/sites/default/files/media/2023TechnicalReportMagnesiumCarbonate_andMagnesiumCarbonateHydroxideHandling.pdf
 |access-date=7 November 2025
 |quote=The report notes that magnesium carbonate can be produced synthetically under controlled laboratory conditions to achieve high-purity grades used in food and pharmaceutical products.}}</ref><ref name="ClimbingMag2024">{{cite news
 |last=Allf
 |first=Bradley
 |title=The Hidden Environmental Cost of Climbing Chalk
 |url=https://www.climbing.com/gear/the-hidden-environmental-cost-of-climbing-chalk/
 |work=Climbing Magazine
 |publisher=Cruz Bay Publishing
 |date=21 May 2018
 |access-date=7 November 2025
 |quote=Most climbing chalks consist of magnesium carbonate (MgCO<sub>3</sub>), often derived from mined magnesite deposits in China.}}</ref> Manufacturers of specialty grip chalks have reported that such refined magnesium carbonate reduces skin irritation and provides a more consistent moisture-absorption profile during athletic use.<ref name="GymBlow2025">{{cite web
 |title=The Cold, Dusty Truth About CaCO<sub>3</sub> vs. MgCO<sub>3</sub>
 |website=Gym Blow Blog
 |publisher=Gym Blow
 |date=13 April 2025
 |url=https://www.gymblow.com/blogs/news/lab-grade-chalk-gym-blow
 |access-date=7 November 2025
 |quote=Gym Blow describes its lab-synthesized magnesium carbonate as being produced from purified magnesium salts and carbonate compounds to remove impurities and improve consistency.}}</ref>

As a [[food additive]], magnesium carbonate is known as E504. Its only known side effect is that it may work as a laxative in high concentrations.<ref>{{cite web|title=Food-Info.net : E-numbers : E504: Magnesium carbonates|url=http://www.food-info.net/uk/e/e504.htm}} 080419 food-info.net</ref>

Magnesium carbonate is used in [[taxidermy]] for whitening skulls. It can be mixed with [[hydrogen peroxide]] to create a paste, which is spread on the skull to give it a white finish.

Magnesium carbonate is used as a matte white coating for [[projection screen]]s.<ref>{{Cite book|title = Certified Technology Specialist-Installation|last = Noronha|first = Shonan|publisher = McGraw Hill Education|year = 2015|isbn = 978-0071835657|pages = 256}}</ref>

===Medical use===
It is a [[laxative]] to loosen the [[bowels]].

In addition, high purity magnesium carbonate is used as an [[antacid]] and as an additive in [[table salt]] to keep it free flowing. Magnesium carbonate can do this because it does not dissolve in water, only in acid, where it will [[Effervescence|effervesce]] (bubble).<ref>{{Cite web|url=https://sciencing.com/magnesium-carbonate-5626269.html|title=What Is Magnesium Carbonate?|website=Sciencing|date=24 April 2017 |language=en|access-date=2018-04-15}}</ref>

== Compendial status ==
* [[British Pharmacopoeia]]<ref name=ib29>{{cite web
 |last=British Pharmacopoeia Commission Secretariat 
 |title=Index, BP 2009 
 |year=2009 
 |url=http://www.pharmacopoeia.co.uk/pdf/2009_index.pdf 
 |access-date=31 January 2010 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20090411071437/http://www.pharmacopoeia.co.uk/pdf/2009_index.pdf 
 |archive-date=11 April 2009 
}}</ref>
* [[Japanese Pharmacopoeia]]<ref name=jp15>{{cite web
 |title=Japanese Pharmacopoeia, Fifteenth Edition 
 |year=2006 
 |url=http://jpdb.nihs.go.jp/jp15e/JP15.pdf 
 |access-date=31 January 2010 
 |url-status=dead 
 |archive-url=https://web.archive.org/web/20110722105441/http://jpdb.nihs.go.jp/jp15e/JP15.pdf 
 |archive-date=22 July 2011 
}}</ref>

== See also ==
* [[Calcium acetate/magnesium carbonate]]
* [[Upsalite]], a reported amorphous form of magnesium carbonate

== Notes and references ==
{{reflist}}

==External links==
{{commons category|Magnesium carbonate}}
*[http://www.inchem.org/documents/icsc/icsc/eics0969.htm International Chemical Safety Card 0969]
*[http://webbook.nist.gov/chemistry/ NIST Standard Reference Database]

{{Carbonates}}
{{Magnesium compounds}}
{{Antacids}}
{{Laxatives}}
{{Authority control}}

{{DEFAULTSORT:Magnesium Carbonate}}
[[Category:Magnesium compounds]]
[[Category:Carbonates]]
[[Category:Antacids]]