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Revision as of 12:11, 15 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 476786940 of page Magnesium_hydroxide for the Chem/Drugbox validation project (updated: 'ChEMBL').		Latest revision as of 11:40, 11 September 2024 edit Oblivy (talk | contribs)Extended confirmed users4,125 editsm Reverted 1 edit by Ayolpl (talk) to last revision by Citation botTags: Twinkle Undo
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			{{Short description|Inorganic compound of formula Mg(OH)2}}
	{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
	{{chembox		{{Chembox
	| Verifiedfields = changed		| Verifiedfields = changed
			| Watchedfields = changed
	| verifiedrevid = 458266305
			| verifiedrevid = 476992492
	| ImageFile = Hydroxid hořečnatý.PNG
			| ImageFile = Hydroxid hořečnatý.PNG
	| ImageSize =
			| ImageSize = 250px
	| ImageName = Magnesium hydroxide
			| ImageName = Magnesium hydroxide
	| ImageFile1 = Brucitestructure.png
			| ImageFile1 = Mg(OH)2Xray.jpg
	| ImageSize1 =
			| ImageSize1 = 250px
	| ImageName1 = Magnesium hydroxide
	| IUPACName = Magnesium hydroxide		| ImageName1 = Magnesium hydroxide
			| IUPACName = Magnesium hydroxide
	| OtherNames = Milk of magnesia
			| OtherNames = {{Unbulleted list|Magnesium dihydroxide|Milk of magnesia}}
	| Section1 = {{Chembox Identifiers
			| pronounce =
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}= {{chemspidercite|changed|chemspider}}= {{chemspidercite|changed|chemspider}}= {{chemspidercite|correct|chemspider}}
			| Section1 = {{Chembox Identifiers
			| CASNo = 1309-42-8
			| CASNo_Ref = {{cascite|correct|CAS}}
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 14107		| ChemSpiderID = 14107
	| ChEMBL_Ref = {{ebicite|changed|EBI}}= {{ebicite|correct|EBI}}= {{ebicite|correct|EBI}}= {{ebicite|changed|EBI}}		| ChEBI_Ref = {{ebicite|correct|EBI}}
			| ChEBI = 6637
	| ChEMBL = <!-- blanked - oldvalue: 1200718 -->
			| ChEMBL_Ref = {{ebicite|correct|EBI}}
	| UNII_Ref = {{fdacite|correct|FDA}}= {{fdacite|changed|FDA}}= {{fdacite|changed|FDA}}= {{fdacite|correct|FDA}}
			| ChEMBL = 1200718
			| DrugBank = DB09104
			| EINECS = 215-170-3
			| Gmelin = 485572
			| KEGG = C07876
			| PubChem = 14791
			| RTECS = OM3570000
			| UNII_Ref = {{fdacite|correct|FDA}}
	| UNII = NBZ3QY004S		| UNII = NBZ3QY004S
	| InChI = 1/Mg.2H2O/h;2*1H2/q+2;;/p-2		| InChI = 1/Mg.2H2O/h;2*1H2/q+2;;/p-2
	| InChIKey = VTHJTEIRLNZDEV-NUQVWONBAW		| InChIKey = VTHJTEIRLNZDEV-NUQVWONBAW
	| ChEBI_Ref = {{ebicite|correct|EBI}}= {{ebicite|changed|EBI}}= {{ebicite|changed|EBI}}= {{ebicite|correct|EBI}}
	| ChEBI = 6637
	| SMILES = ..		| SMILES = ..
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}= {{stdinchicite|changed|chemspider}}= {{stdinchicite|changed|chemspider}}= {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI = 1S/Mg.2H2O/h;2*1H2/q+2;;/p-2		| StdInChI = 1S/Mg.2H2O/h;2*1H2/q+2;;/p-2
	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}= {{stdinchicite|changed|chemspider}}= {{stdinchicite|changed|chemspider}}= {{stdinchicite|correct|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChIKey = VTHJTEIRLNZDEV-UHFFFAOYSA-L		| StdInChIKey = VTHJTEIRLNZDEV-UHFFFAOYSA-L
			}}
	| CASNo = 1309-42-8
			| Section2 = {{Chembox Properties
	| CASNo_Ref = {{cascite|correct|CAS}}= {{cascite|changed|??}}= {{cascite|changed|??}}= {{cascite|correct|CAS}}
	| PubChem = 14791
	| RTECS = OM3570000
	| ATCCode_prefix = A02
	| ATCCode_suffix = AA04
	| ATC_Supplemental = {{ATC|G04|BX01}}
	}}
	| Section2 = {{Chembox Properties
	| Formula = Mg(OH)<sub>2</sub>		| Formula = Mg(OH)<sub>2</sub>
	| MolarMass = 58.3197 g/mol		| MolarMass = 58.3197 g/mol
	| Appearance = White solid		| Appearance = White solid
			| Odor = Odorless
	| Density = 2.3446 g/cm<sup>3</sup>
			| Density = 2.3446{{nbsp}}g/cm<sup>3</sup>
	| MeltingPt = 350 °C (decomp.)
	| BoilingPt =		| MeltingPtC = 350
			| MeltingPt_notes = decomposes
	| Solubility = 0.012 g/L
			| Solubility = {{ubl
	| SolubilityProduct = 1.5×10<sup>−11</sup>
			| 0.00064{{nbsp}}g/100{{nbsp}}mL (25{{nbsp}}°C)
	| RefractIndex = 1.559<ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, ISBN 0070494398</ref>}}
			| 0.004{{nbsp}}g/100{{nbsp}}mL (100{{nbsp}}°C)
	| Section3 = {{Chembox Structure
			}}
	| CrystalStruct = Hexagonal, ]<ref>{{cite journal|doi=10.1143/JPSJ.39.317|title=Magnetic Behaviours of a Random Magnet, NipMg(1-p)(OH2)|author=Toshiaki Enoki and Ikuji Tsujikawa |journal=J. Phys. Soc. Jpn. |volume=39|year=1975|pages=317–323|issue=2}}</ref>
			| SolubilityProduct = {{val|5.61e-12}}
			| RefractIndex = 1.559<ref>{{Cite book |last=Patnaik |first=Pradyot |url=https://www.worldcat.org/oclc/50252041 |title=Handbook of inorganic chemicals |date=2003 |publisher=McGraw-Hill |isbn=0-07-049439-8 |location=New York |oclc=50252041}}</ref>
			| MagSus = {{val|-22.1e-6|u=cm<sup>3</sup>/mol}}
			}}
			| Section3 = {{Chembox Structure
			| CrystalStruct = Hexagonal, ]<ref>{{cite journal|doi=10.1143/JPSJ.39.317|title=Magnetic Behaviours of a Random Magnet, Ni<sub>''p''</sub>Mg<sub>(1&minus;''p'')</sub>(OH)<sub>2</sub>|last1=Toshiaki Enoki |last2=Ikuji Tsujikawa |name-list-style=and |journal=J. Phys. Soc. Jpn. |volume=39|year=1975|pages=317–323|issue=2|bibcode=1975JPSJ...39..317E}}</ref>
	| SpaceGroup = P{{overline|3}}m1 No. 164		| SpaceGroup = P{{overline|3}}m1 No. 164
	| Coordination =		| Coordination =
	| LattConst_a = 0.312 nm		| LattConst_a = 0.312{{nbsp}}nm
	| LattConst_b =		| LattConst_b =
	| LattConst_c = 0.473 nm		| LattConst_c = 0.473{{nbsp}}nm
	| LattConst_alpha =		| LattConst_alpha =
	| LattConst_beta =		| LattConst_beta =
	| LattConst_gamma =		| LattConst_gamma =
	| MolShape =		| MolShape =
	| OrbitalHybridisation =		| OrbitalHybridisation =
	| Dipole =		| Dipole =
	}}
	| Section4 = {{Chembox Thermochemistry
	| DeltaHf = −925&nbsp;kJ·mol<sup>−1</sup><ref name=b1>{{cite book| author = Zumdahl, Steven S.|title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 061894690X|page=A22}}</ref>
	| Entropy = 64&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
	}}		}}
	| Section7 = {{Chembox Hazards		| Section5 = {{Chembox Thermochemistry
			| DeltaHf = −924.7&nbsp;kJ·mol<sup>−1</sup><ref name="b1">{{Cite book |last=Zumdahl |first=Steven S. |title=Chemical Principles |publisher=Houghton Mifflin Company |year=2009 |isbn=978-0-618-94690-7 |edition=6th |page=A22}}</ref>
	| ExternalMSDS =
			| DeltaGf = −833.7{{nbsp}}kJ/mol
	| EUIndex = Not listed
			| Entropy = 64&nbsp;J·mol<sup>−1</sup>·K<sup>−1</sup><ref name=b1/>
	| MainHazards =
			| HeatCapacity = 77.03{{nbsp}}J/mol·K
			}}
			| Section6 = {{Chembox Pharmacology
			| ATCCode_prefix = A02
			| ATCCode_suffix = AA04
			| ATC_Supplemental = {{ATC|G04|BX01}}
			}}
			| Section7 = {{Chembox Hazards
			| ExternalSDS =
			| GHSPictograms = {{GHS07}}<ref name=sds>{{cite web |title=Magnesium Hydroxide |url=https://www.americanelements.com/magnesium-hydroxide-1309-42-8 |publisher=] |access-date=May 9, 2019}}</ref>
			| GHSSignalWord = Warning<ref name=sds/>
			| HPhrases = {{H-phrases|315|319|335}}<ref name=sds/>
			| PPhrases = {{P-phrases|261|280|305+351+338|304+340|405|501}}<ref name=sds/>
			| MainHazards =
	| NFPA-H = 1		| NFPA-H = 1
	| NFPA-F = 0		| NFPA-F = 0
	| NFPA-R = 0		| NFPA-R = 0
	| NFPA-O =		| NFPA-S =
	| FlashPt = Non-flammable		| FlashPt = Non-flammable
	| Autoignition =		| AutoignitionPt =
			| LD50 = 8500{{nbsp}}mg/kg (rat, oral)
	}}
			}}
	| Section8 = {{Chembox Related
			| Section8 = {{Chembox Related
	| OtherAnions = ]		| OtherAnions = ]
	| OtherCations = ]<br/>]<br/>]<br/>]		| OtherCations = {{ubl
			| ]
			| ]
			| ]
			| ]
	}}		}}
			}}
	}}		}}
			'''Magnesium hydroxide''' is an ] with the chemical formula Mg(OH)<sub>2</sub>. It occurs in nature as the mineral ]. It is a white solid with low solubility in water ({{nowrap|] {{=}} {{val|5.61e-12}}}}).<ref>{{cite book|title=Handbook of Chemistry and Physics|date=12 March 1996|publisher=CRC Press|isbn=0849305969|edition=76th}}</ref> Magnesium hydroxide is a common component of ]s, such as '''milk of magnesia'''.
			==Preparation==
			Treating the solution of different soluble magnesium salts with ] water induces the ] of the solid hydroxide Mg(OH)<sub>2</sub>:
			:Mg<sup>2+</sup> + 2&nbsp;OH<sup>−</sup> → Mg(OH)<sub>2</sub>
			As {{chem|Mg|2+}} is the second most abundant cation present in ] after {{chem|Na|+}}, it can be economically extracted directly from seawater by ] as described here above. On an industrial scale, Mg(OH)<sub>2</sub> is produced by treating seawater with ] (Ca(OH)<sub>2</sub>). A volume of {{cvt|600|m3|USgal}} of seawater gives about {{convert|1|t|lb}} of Mg(OH)<sub>2</sub>. Ca(OH)<sub>2</sub> {{nowrap|(] {{=}} {{val|5.02e-6}}}})<ref name="CRC">{{cite book |first=John |last=Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=5-188<!-- hyphen not range -->|edition=99th |language=English}}</ref> is far more soluble than Mg(OH)<sub>2</sub> {{nowrap|(] {{=}} {{val|5.61e-12}}}}) and drastically increases the ] value of seawater from 8.2 to 12.5. The less soluble {{chem|Mg|(OH)|2}} precipitates because of the ] due to the {{chem|OH|-}} added by the dissolution of {{chem|Ca|(OH)|2}}:<ref name="ullmann">{{Ullmann|title=Magnesium Compounds|doi=10.1002/14356007.a15_595.pub2|last1=Seeger|first1=Margarete|last2=Otto|first2=Walter|last3=Flick|first3=Wilhelm|last4=Bickelhaupt|first4=Friedrich|last5=Akkerman|first5=Otto S.}}</ref>
			:{{chem2|Mg(2+) + Ca(OH)2 -> Mg(OH)2 + Ca(2+)}}
			For seawater brines, precipitating agents other than {{chem2|Ca(OH)2}} can be utilized, each with their own nuances:
			* Use of {{chem2|Ca(OH)2}} can yield {{chem2|CaSO4}} or {{chem2|CaCO3}}, which reduces the final purity of {{chem2|Mg(OH)2}}.
			* {{chem2|NH4OH}}, can produce explosive nitrogen trichloride when the brine is used for chlorine production.
			* {{chem2|NaOH}} as the precipitating agent has longer settling times and is difficult to filter.
			It has been demonstrated that sodium hydroxide, {{chem2|NaOH}}, is the better precipitating agent compared to {{chem2|Ca(OH)2}} and {{chem2|NH4OH}} due to higher recovery and purity rates, and the settling and filtration time can be improved at low temperatures and higher concentration of precipitates. Methods involving the use of precipitating agents are typically batch processes.<ref>{{cite journal |last1=Fontana |first1=Danilo |last2=Forte |first2=Federica |last3=Pietrantonio |first3=Massimiliana |last4=Pucciarmati |first4=Stefano |last5=Marcoaldi |first5=Caterina |title=Magnesium recovery from seawater desalination brines: a technical review |journal=Environment, Development and Sustainability |date=2023-12-01 |volume=25 |issue=12 |pages=13733–13754 |doi=10.1007/s10668-022-02663-2 |ref=fontana2023|doi-access=free |bibcode=2023EDSus..2513733F }}</ref>
			It is also possible to obtain {{chem2|Mg(OH)2}} from seawater using electrolysis chambers separated with a cation exchange membrane. This process is continuous, lower-cost, and produces oxygen gas, hydrogen gas, sulfuric acid (if {{chem2|Na2SO4}} is used; {{chem2|NaCl}} can alternatively be used to yield {{chem2|HCl}}), and {{chem2|Mg(OH)2}} of 98% or higher purity. It is crucial to deaerate the seawater to mitigate co-precipitation of calcium precipitates.<ref name="sano2018">{{cite journal |last1=Sano |first1=Yoshihiko |last2=Hao |first2=YiJia |last3=Kuwahara |first3=Fujio |title=Development of an electrolysis based system to continuously recover magnesium from seawater |journal=Heliyon |date=2018-11-01 |volume=4 |issue=11 |pages=e00923 |doi=10.1016/j.heliyon.2018.e00923 |doi-access=free |pmid=30839823 |pmc=6249789 |bibcode=2018Heliy...400923S }}</ref>
			==Uses==
			===Precursor to MgO===
			Most Mg(OH)<sub>2</sub> that is produced industrially, as well as the small amount that is mined, is converted to fused ] (MgO). Magnesia is valuable because it is both a poor electrical conductor and an excellent thermal conductor.<ref name=ullmann/>
			===Medical===
			Only a small amount of the magnesium from magnesium hydroxide is usually absorbed by the intestine (unless one is deficient in magnesium). However, magnesium is mainly excreted by the kidneys; so long-term, daily consumption of milk of magnesia by someone suffering from kidney failure could lead in theory to ]. Unabsorbed magnesium is excreted in feces; absorbed magnesium is rapidly excreted in urine.<ref>{{Cite web |title=magnesium hydroxide |url=https://www.glowm.com/resources/glowm/cd/pages/drugs/m001.html |archive-url=https://web.archive.org/web/20180114020205/https://www.glowm.com/resources/glowm/cd/pages/drugs/m001.html |archive-date=14 January 2018 |access-date=2023-03-14 |publisher=] |language=en}}</ref>
			], ]]]
			====Applications====
			=====Antacid=====
			As an antacid, magnesium hydroxide is dosed at approximately 0.5–1.5{{nbsp}}g in adults and works by simple ], in which the ] ]s from the Mg(OH)<sub>2</sub> combine with ]ic H<sup>+</sup> ]s (or ] ions) produced in the form of hydrochloric acid by ]s in the ], to produce water.
			=====Laxative=====
			As a laxative, magnesium hydroxide is dosed at {{convert|5|–|10|g}}, and works in a number of ways. First, Mg<sup>2+</sup> is poorly absorbed from the intestinal tract, so it draws water from the surrounding tissue by ]. Not only does this increase in water content soften the feces, it also increases the volume of feces in the intestine (intraluminal volume) which naturally stimulates intestinal ]. Furthermore, Mg<sup>2+</sup> ions cause the release of ] (CCK), which results in intraluminal accumulation of water and electrolytes, and increased intestinal motility. Some sources claim that the hydroxide ions themselves do not play a significant role in the laxative effects of milk of magnesia, as alkaline solutions (i.e., solutions of hydroxide ions) are not strongly laxative, and non-alkaline Mg<sup>2+</sup> solutions, like ], are equally strong laxatives, ] for mole.<ref>{{Cite journal |last1=Tedesco |first1=Frances J. |last2=DiPiro |first2=Joseph T. |year=1985 |title=Laxative use in constipation |journal=] |volume=80 |issue=4 |pages=303–309 |pmid=2984923}}</ref>
			====History of milk of magnesia====
			On May 4, 1818, American inventor Koen Burrows received a patent (No. X2952) for magnesium hydroxide.<ref>{{US patent|X2952|Patent USX2952 - Magnesia, medicated, liquid - Google Patents}}</ref> In 1829, ] used a "condensed solution of fluid magnesia" preparation of his own design<ref>]. ''A World Elsewhere'' (1993), p. 2.</ref> to treat the ], the ], for stomach pain. This was so successful (advertised in Australia and approved by the Royal College of Surgeons in 1838)<ref>{{Cite news |url=https://news.google.com/newspapers?nid=1301&dat=18461007&id=ERkRAAAAIBAJ&pg=6490,1153513 |title=Sir James Murray's condensed solution of fluid magnesia |work=] |date=October 7, 1846 |volume=21 |issue=2928 |page=1, column 4}}</ref> that he was appointed resident physician to Anglesey and two subsequent Lords Lieutenant, and knighted. His fluid magnesia product was patented two years after his death, in 1873.<ref> {{webarchive|url=https://web.archive.org/web/20110605061937/http://www.ulsterhistory.co.uk/jamesmurray.htm |date=2011-06-05 }}, 24 February 2005</ref>
			The term ''milk of magnesia'' was first used by ] in 1872 for a ] of magnesium hydroxide formulated at about 8].<ref> {{Webarchive|url=https://web.archive.org/web/20170622220811/https://www.phillipsdigestive.com/frequently-asked-question/#quest19 |date=2017-06-22 }} FAQ, phillipsrelief.com, accessed 4 July 2016</ref> It was sold under the brand name ''Phillips' Milk of Magnesia'' for medicinal usage.
			] registrations show that the terms "Milk of Magnesia"<ref></ref> and "Phillips' Milk of Magnesia"<ref></ref> have both been assigned to ] since 1995. In the UK, the non-brand (generic) name of "Milk of Magnesia" and "Phillips' Milk of Magnesia" is "Cream of Magnesia" (Magnesium Hydroxide Mixture, ]).
			===As food additive===
			It is added directly to human food, and is affirmed as ] by the ].<ref>{{cite web |title=Compound Summary for CID 14791 - Magnesium Hydroxide |url=https://pubchem.ncbi.nlm.nih.gov/compound/14791 |publisher=PubChem}}</ref> It is known as ] '''E528'''.
			Magnesium hydroxide is marketed for medical use as chewable tablets, as capsules, powder, and as liquid ], sometimes flavored. These products are sold as ]s to neutralize stomach ] and relieve ] and ]. It also is a laxative to alleviate ]. As a laxative, the ] force of the magnesia acts to draw fluids from the body. High doses can lead to ], and can deplete the body's supply of ], sometimes leading to ].<ref></ref>
			Some magnesium hydroxide products sold for antacid use (such as ]) are formulated to minimize unwanted laxative effects through the inclusion of ], which inhibits the contractions of ] cells in the gastrointestinal tract,<ref name="Washington1991">{{cite book|last1=Washington|first1=Neena|title=Antacids and Anti Reflux Agents|date=2 August 1991|publisher=CRC Press|location=Boca Raton, FL|isbn=0-8493-5444-7|page=10}}</ref> thereby counterbalancing the contractions induced by the osmotic effects of the magnesium hydroxide.
			===Other niche uses===
			Magnesium hydroxide is also a component of ].<ref></ref>
			====Waste water treatment====
			Magnesium hydroxide powder is used industrially to neutralize acidic wastewaters.<ref>Aileen Gibson and Michael Maniocha. , August 12, 2004</ref> It is also a component of the ] method of building ]s. The main advantage of {{chem|Mg|(OH)|2}} over {{chem|Ca|(OH)|2}}, is to impose a lower pH better compatible with that of seawater and sea life: pH 10.5 for {{chem|Mg|(OH)|2}} in place of pH 12.5 with {{chem|Ca|(OH)|2}}.
			====Fire retardant====
			Natural magnesium hydroxide (]) is used commercially as a fire retardant. Most industrially used magnesium hydroxide is produced synthetically.<ref>{{cite book|last=Rothon|first=RN|title=Particulate Filled Polymer Composites|year=2003|publisher=Rapra Technology|location=Shrewsbury, UK|pages=53–100}}</ref> Like aluminum hydroxide, solid magnesium hydroxide has smoke suppressing and ] properties. This property is attributable to the ] it undergoes at {{cvt|332|C}}:
			:Mg(OH)<sub>2</sub> → MgO + H<sub>2</sub>O
			The heat absorbed by the reaction retards the fire by delaying ignition of the associated substance. The water released dilutes combustible gases. Common uses of magnesium hydroxide as a flame retardant include additives to cable insulation, insulation plastics, roofing, and various flame retardant coatings.<ref name="Rev1">{{cite journal |last1=Hollingbery |first1=LA |last2=Hull |first2=TR |year=2010 |title=The Thermal Decomposition of Huntite and Hydromagnesite - A Review |url=http://clok.uclan.ac.uk/1139 |journal=Thermochimica Acta |volume=509 |issue=1–2 |pages=1–11 |doi=10.1016/j.tca.2010.06.012}}</ref><ref name="Rev2">{{cite journal |last1=Hollingbery |first1=LA |last2=Hull |first2=TR |year=2010 |title=The Fire Retardant Behaviour of Huntite and Hydromagnesite - A Review |url=http://clok.uclan.ac.uk/1432 |journal=Polymer Degradation and Stability |volume=95 |issue=12 |pages=2213–2225 |doi=10.1016/j.polymdegradstab.2010.08.019}}</ref><ref name="Fire1">{{cite journal |last1=Hollingbery |first1=LA |last2=Hull |first2=TR |year=2012 |title=The Fire Retardant Effects of Huntite in Natural Mixtures with Hydromagnesite |url=http://clok.uclan.ac.uk/3420/ |journal=Polymer Degradation and Stability |volume=97 |issue=4 |pages=504–512 |doi=10.1016/j.polymdegradstab.2012.01.024}}</ref><ref name="Therm1">{{cite journal |last1=Hollingbery |first1=LA |last2=Hull |first2=TR |year=2012 |title=The Thermal Decomposition of Natural Mixtures of Huntite and Hydromagnesite |url=http://clok.uclan.ac.uk/3414 |journal=Thermochimica Acta |volume=528 |pages=45–52 |doi=10.1016/j.tca.2011.11.002|bibcode=2012TcAc..528...45H }}</ref><ref name="Fire2">{{cite journal |last1=Hull |first1=TR |last2=Witkowski |first2=A |last3=Hollingbery |first3=LA |year=2011 |title=Fire Retardant Action of Mineral Fillers |url=http://clok.uclan.ac.uk/2963 |journal=Polymer Degradation and Stability |volume=96 |issue=8 |pages=1462–1469 |doi=10.1016/j.polymdegradstab.2011.05.006 |s2cid=96208830}}</ref>
			==Mineralogy==
			] crystals (mineral form of Mg(OH)<sub>2</sub>) from the Sverdlovsk Region, Urals, Russia (size: {{cvt|10.5|×|7.8|×|7.4|cm|disp=or}})]]
			], the mineral form of Mg(OH)<sub>2</sub> commonly found in nature also occurs in the 1:2:1 ]s amongst others, in ], in which it occupies the interlayer position normally filled by monovalent and divalent ]s such as Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup> and Ca<sup>2+</sup>. As a consequence, chlorite interlayers are cemented by brucite and cannot swell nor shrink.
			Brucite, in which some of the Mg<sup>2+</sup> cations have been substituted by Al<sup>3+</sup> cations, becomes positively charged and constitutes the main basis of ] (LDH). LDH minerals as ] are powerful anion sorbents but are relatively rare in nature.
			Brucite may also crystallize in ] and ] in contact with ]. Indeed, the Mg<sup>2+</sup> cation is the second-most-abundant cation in seawater, just behind Na<sup>+</sup> and before Ca<sup>2+</sup>. Because brucite is a swelling mineral, it causes a local volumetric expansion responsible for tensile stress in concrete. This leads to the formation of cracks and fissures in concrete, accelerating its degradation in seawater.
			For the same reason, ] cannot be used as ] for making concrete. The reaction of ] with the free alkali ]s present in the cement porewater also leads to the formation of expansive brucite.
			:MgCO<sub>3</sub> + 2 NaOH → Mg(OH)<sub>2</sub> + Na<sub>2</sub>CO<sub>3</sub>
			This reaction, one of the two main ] (AAR) is also known as ].
			==See also==
			* ] – calcium hydroxyde: {{chem|Ca|(OH)|2}}
			==References==
			{{reflist|30em}}
			{{Magnesium compounds}}
			{{Hydroxides}}
			{{Urologicals}}
			{{Antacids}}
			{{Laxatives}}
			{{DEFAULTSORT:Magnesium Hydroxide}}
			]
			]
			]
			]
			]
			]