vaterite

{{Short description|Calcium carbonate mineral}}

{{Infobox mineral

| name = Vaterite

| boxwidth =

| boxbgcolor =

| image = Vaterite2-San Vito, Monte Somma, Italy.tif

| imagesize =

| alt =

| caption = Vaterite from San Vito quarry, San Vito, Monte Somma, Somma-Vesuvius Complex, Italy

| category = Carbonate minerals

| formula = CaCO₃

| IMAsymbol = Vtr{{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}}

| molweight =

| strunz = 5.AB.20

| dana =

| system = Hexagonal

| class = Dihexagonal dipyramidal (6mmm)
H-M symbol: (6/m 2/m 2/m)

| symmetry = P6₃/mmc {P6₃/m 2/m 2/c}

| unit cell = a = 4.13, c = 8.49 [Å]; Z = 6

| color = Colorless

| colour =

| habit = Fine fibrous crystals, typically less than 0.1 mm, in spherulitic aggregates.

| twinning =

| cleavage =

| fracture = Irregular to uneven, splintery

| tenacity = Brittle

| mohs = 3

| luster = Sub-vitreous, waxy

| streak =

| diaphaneity = Transparent to semi-transparent

| gravity = 2.54

| density =

| polish =

| opticalprop = Uniaxial (+)

| refractive = n_ω = 1.550 n_ε = 1.650

| birefringence = δ = 0.100

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| references = [http://www.mindat.org/min-4161.html Mindat.org][http://rruff.geo.arizona.edu/doclib/hom/vaterite.pdf Handbook of Mineralogy][http://webmineral.com/data/Vaterite.shtml Webmineral data]

}}

Vaterite is a mineral, a polymorph of calcium carbonate (CaCO₃). It was named after the German mineralogist Heinrich Vater. It is also known as mu-calcium carbonate (μ-CaCO₃). Vaterite belongs to the hexagonal crystal system, whereas calcite is trigonal and aragonite is orthorhombic.

Vaterite, like aragonite, is a metastable phase of calcium carbonate at ambient conditions at the surface of the Earth. As it is less stable than either calcite, the most stable polymorph,{{cite journal|last1=Ni|first1=Ming|last2=Ratner|first2=Buddy D.|title=Differentiation of Calcium Carbonate Polymorphs by Surface Analysis Techniques – An XPS and TOF-SIMS study|journal=Surface and Interface Analysis|volume=40|issue=10|pages=1356-1361|doi=10.1002/sia.2904|year=2008|pmc=4096336|pmid=25031482}} or aragonite, vaterite has a higher solubility than either of these phases. Therefore, once vaterite is exposed to water, it converts to calcite (at low temperature) or aragonite (at high temperature: ~60 °C). At 37 °C for example a solution-mediated transition from vaterite to calcite occurs, where the vaterite dissolves and subsequently precipitates as calcite assisted by an Ostwald ripening process.{{cite journal | first1= Gen-Tao |last1=Zhou | first2=Qi-Zhi |last2=Yao | first3=Sheng-Quan |last3=Fu | first4=Ye-Bin |last4=Guan | url= http://eurjmin.geoscienceworld.org/content/22/2/259| date=2010|title =Controlled crystallization of unstable vaterite with distinct morphologies and their polymorphic transition to stable calcite| doi= 10.1127/0935-1221/2009/0022-2008 | journal= European Journal of Mineralogy|volume=22 |issue=2 |pages=259–269 |bibcode=2010EJMin..22..259Z }}

However, vaterite does occur naturally in mineral springs, organic tissue, gallstones, urinary calculi and plants. In those circumstances, some impurities (metal ions or organic matter) may stabilize the vaterite and prevent its transformation into calcite or aragonite. Vaterite is usually colorless.

Vaterite can be produced as the first mineral deposits repairing natural or experimentally-induced shell damage in some aragonite-shelled mollusks (e.g. gastropods). Subsequent shell deposition occurs as aragonite. In 2018, vaterite was identified as a constituent of a deposit formed on the leaves of Saxifraga at Cambridge University Botanic Garden.{{cite news|title=Incredible discovery at Cambridge's Botanic Garden that could transform treatment of cancer|url=https://www.cambridge-news.co.uk/news/cambridge-news/botanic-garden-cambridge-vaterite-cancer-14399149|date=12 Mar 2018|archiveurl=https://web.archive.org/web/20180312131958/https://www.cambridge-news.co.uk/news/cambridge-news/botanic-garden-cambridge-vaterite-cancer-14399149|archivedate=2018-03-12|newspaper=Cambridge News|author=Chris Elliott}}{{cite web|title=Rare mineral discovered in plants for first time|url=https://www.sciencedaily.com/releases/2018/03/180305101631.htm|date=5 Mar 2018|website=Science Daily}}

Vaterite is tapped as an effective intermediate form of cement whose production consumes carbon dioxide rather than emitting it. Research into the vaterite production process was inspired by its discovery in the hard skeletons of coral.{{cite news|title=Cement has an emissions problem. Can tech that mimics coral fix it?|url=https://www.canarymedia.com/articles/clean-industry/cement-has-an-emissions-problem-can-tech-that-mimics-coral-fix-it?|date=22 Jan 2025|author=Isobel Whitcomb}}{{rs inline|date=January 2025}}

Vaterite has a JCPDS number of {{not a typo|13-192}}.

File:Vaterite.png

File:Vaterite1-San Vito, Monte Somma, Italy.tif) are microcrystalline with largest crystals below 2 mm size. This vaterite is epitactic after aragonite. The crystal contains triplet of aragonite inside of it. On its termination twin seams of aragonite triplet are well visible.]]