{{Short description|Pentahydrated magnesium carbonate}} {{Infobox mineral | name = Lansfordite | boxwidth = | boxbgcolor = | image = Lansfordite.jpg | imagesize = | alt = Photo of magnesium crystals | caption = Lansfordite crystals in Switzerland | category = Carbonates | formula = {{Format molecular formula|MgCO3·5H2O}} | IMAsymbol = Lfd<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}</ref> | molweight = 174.39 | strunz = 5/D.01-30 | dana = 15.1.6.1 | system = Monoclinic | class = | symmetry = ''P2<sub>1</sub>/c'' (No. 14) | unit cell = a=7.3458 Å, b=7.6232 Å, c=12.4737 Å, β=101.722° | colour = Colourless, white after exposure | habit = Crystals, stalactites terminated by crystal faces, efflorescences, parallel growths. | twinning = | cleavage = Perfect, Distinct | fracture = | tenacity = | toughness = | mohs = 2.5 | luster = Vitreous (if fresh) | streak = White | diaphaneity = Translucent, opaque after exposure | gravity = 1.6 | density = 1.6 | polish = | opticalprop = | refractive = | birefringence = 0.042 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | Curie temp = | fusibility = | diagnostic = | solubility = | impurities = | alteration = }} '''Lansfordite''' is a mineral of magnesium carbonate ({{chem|Mg|C|O|3}}). It represents the pentahydrate of magnesium carbonate, and has the total formula {{Format molecular formula|MgCO3·5H2O}}.<ref name=webmineral>{{Cite web|title=Lansfordite Mineral Data|url=http://www.webmineral.com/data/Lansfordite.shtml|access-date=2021-02-15|website=www.webmineral.com}}</ref> Landsfordite was discovered in 1888 in a coal mine in Lansford, Pennsylvania. It crystallizes in the monoclinic system (space group ''P2<sub>1</sub>/c''<ref>{{cite journal |last1=Liu |first1=B.N. |last2=Zhou |first2=X.T. |last3=Cui |first3=X.S. |last4=Tang |first4=J.G. |journal=Science in China |volume=B33 |year=1990 |pages=1350–1356 |title=Synthesis of lansfordite MgCO3*5H2O and its crystal structure investigation}}</ref>) and typically occurs as colorless to white prismatic crystals and stalactitic masses.<ref>{{Cite web|title=LANSFORDITE|url=http://euromin.w3sites.net//mineraux/LANSFORDITE.html|access-date=2021-02-15|website=euromin.w3sites.net}}</ref> It is a soft mineral, Mohs hardness of 2.5, with a low specific gravity of 1.7. It is transparent to translucent with refractive indices of 1.46 to 1.51.<ref>{{Cite web|title=Lansfordite|url=https://www.mindat.org/min-2324.html|access-date=2021-02-15|website=www.mindat.org}}</ref> The mineral will effloresce at room temperature, producing nesquehonite.<ref>{{Cite web|last=|first=|date=|title=Lansfordite|url=http://www.handbookofmineralogy.com/pdfs/lansfordite.pdf|archive-url=https://web.archive.org/web/20160304061411/http://www.handbookofmineralogy.com/pdfs/lansfordite.pdf|archive-date=4 March 2016|access-date=15 February 2021|website=Handbook of Mineralogy|url-status=dead}}</ref>
==References== {{Reflist}}
Category:Magnesium minerals Category:Carbonate minerals Category:Geology of Pennsylvania Category:Monoclinic minerals Category:Pentahydrate minerals Category:Minerals in space group 14 Category:Minerals described in 1888
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