Chlormayenite

{{Short description|Mayenite supergroup, mayenite mineral}} {{infobox mineral | name = Chlormayenite | boxwidth = | boxbgcolor = | image = Calcium heptaaluminate str.png | imagesize = | alt = | caption = Crystal structure of chlormayenite (Cl⁻ ions are omitted for clarity)<ref name=hosono>{{Cite journal | doi = 10.1088/1468-6996/16/3/033503| pmid = 27877784| title = Exploration of new superconductors and functional materials, and fabrication of superconducting tapes and wires of iron pnictides| journal = Science and Technology of Advanced Materials| volume = 16| issue = 3| article-number = 033503| year = 2015| last1 = Hosono | first1 = H. | last2 = Tanabe | first2 = K. | last3 = Takayama-Muromachi | first3 = E. | last4 = Kageyama | first4 = H. | last5 = Yamanaka | first5 = S. | last6 = Kumakura | first6 = H. | last7 = Nohara | first7 = M. | last8 = Hiramatsu | first8 = H. | last9 = Fujitsu | first9 = S. |pmc=5099821|bibcode = 2015STAdM..16c3503H |arxiv = 1505.02240}}</ref> | category = Oxide mineral <br/>Mayenite supergroup | formula = Ca₁₂Al₁₄O₃₂[☐₄Cl₂] | IMAsymbol=Cmy<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 = | strunz = 4.CC.20 | dana = | system = Cubic | class = Hextetrahedral ({{overline|4}}3m) <br />H-M symbol: ({{overline|4}} 3m) | symmetry = ''I''{{overline|4}}3d | unit cell = a = 11.98&nbsp;Å; Z&nbsp;=&nbsp;2 | color = Colorless | habit = Microscopic anhedral grains | twinning = | cleavage = | fracture = | tenacity = | mohs = | luster = | streak = White | diaphaneity = Transparent | gravity = 2.85 | density = | polish = | opticalprop = Isotropic | refractive = 1.614–1.643 | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = Absorbs water on exposure | other = | references = <ref name=HBM>{{cite book|editor1=Anthony, John W. |editor2=Bideaux, Richard A. |editor3=Bladh, Kenneth W. |editor4=Nichols, Monte C. |title= Handbook of Mineralogy|publisher= Mineralogical Society of America|place= Chantilly, VA, US|url=http://www.handbookofmineralogy.org/pdfs/mayenite.pdf|chapter=Mayenite|isbn=0-9622097-2-4 |volume=III (Halides, Hydroxides, Oxides)|year=1997}}</ref><ref name=Mindat>[http://www.mindat.org/min-2606.html Chlormayenite]. Mindat</ref><ref name=Webmin>[http://www.webmineral.com/data/Mayenite.shtml Mayenite]. Webmineral</ref> }} '''Chlormayenite''' (after Mayen, Germany), Ca₁₂Al₁₄O₃₂[☐₄Cl₂], is a rare calcium aluminium oxide mineral of cubic symmetry.

It was originally reported from Eifel volcanic complex (Germany) in 1964. It is also found at pyrometamorphic sites such as in the Hatrurim Formation of Israel and in some burned coal dumps.<ref>Sokol E.V., Maksimova N.V., Nigmatulina E.N., Sharygin V.V. and Kalugin V.M. (2005) ''Combustion metamorphism,'' Novosibirsk: Publishing House of the SB RAS. </ref><ref name=HBM/>

It occurs in thermally altered limestone xenoliths within basalts in Mayen, Germany and Klöch, Styria, Austria. In the Hatrurim of Israel it occurs in thermally altered limestones. It occurs with calcite, ettringite, wollastonite, larnite, brownmillerite, gehlenite, diopside, pyrrhotite, grossular, spinel, afwillite, jennite, portlandite, jasmundite, melilite, kalsilite and corundum in the limestone xenoliths. In the Hatrurim it occurs with spurrite, larnite, grossite and brownmillerite.<ref name=HBM/>

Synthetic Ca₁₂Al₁₄O₃₃ and Ca₁₂Al₁₄O₃₂(OH)₂ are known, they are stabilized by moisture instead of chlorine.<ref name=Mindat/><ref name=b2>{{cite book|author1=Ginley, David |author2=Hosono, Hideo |author3=Paine, David C. |title=Handbook of Transparent Conductors|url=https://books.google.com/books?id=K0qjBlrAGYsC|date= 2010|publisher=Springer Science & Business Media|isbn=978-1-4419-1638-9|pages=318 ff}}</ref> The formula can be written as [Ca₁₂Al₁₄O₃₂]O,<ref>{{Cite journal | pmid = 18281939 | year = 2008 | last1 = Palacios | first1 = L | title = Structure and electrons in mayenite electrides | journal = Inorganic Chemistry | volume = 47 | issue = 7 | pages = 2661–7 | last2 = Cabeza | first2 = A | last3 = Bruque | first3 = S | last4 = García-Granda | first4 = S | last5 = Aranda | first5 = M. A. | doi = 10.1021/ic7021193 | hdl = 10651/6543 | hdl-access = free }}</ref> which refers to the unique feature: anion diffusion process.<ref>Boysen H., Kaiser-Bischoff I. and Lerch M. (2007) Anion Diffusion Processes in O- and N-Mayenite Investigated by Neutron Powder Diffraction. Bunsen Colloquium: Diffusion and Reactions in Advanced Materials (September 27th–28th, Clausthal-Zellerfeld, Germany) / The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application.</ref>

Chlormayenite is also found as calcium aluminate in cement where its formula is also written as 11CaO·7 Al₂O₃·CaCl₂, or C₁₁A₇CaCl₂ in the cement chemist notation.

==See also== * Calcium aluminate cements

==References== {{Reflist}}

Category:Oxide minerals Category:Calcium minerals Category:Aluminium minerals Category:Cubic minerals Category:Minerals in space group 220 Category:Cement Category:Concrete

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