Andrianovite

{{Short description|Rare cyclosilicate mineral}} {{infobox mineral | name = Andrianovite | category = Silicate mineral, Cyclosilicate | image = Andrianovite.jpg | imagesize = 260 | alt = | caption = Andrianovite found in Russia | formula = Na₁₂(K,Sr,Ce)₃Ca₆Mn₃Zr₃Nb(Si₂₅O₇₃)(O,H₂O,OH)₅ (original form) |IMAsymbol=Adv<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> | strunz = 9.CO.10 | dana = 64.1.2.4 | system = Trigonal | class = Ditrigonal pyramidal (3m) <br/>H-M symbol: (3m) | symmetry = ''R3m'' | unit cell = a = 14.28, c = 30.24&nbsp;[Å] (approximated); Z&nbsp;=&nbsp;3 | color = Light yellow | colour = | habit = intergrowths (rims) with eudialyte | twinning = | cleavage = (001), imperfect | fracture = Step-like | tenacity = Brittle | mohs = 5 | luster = Vitreous | streak = White | diaphaneity = Transparent | gravity = | density = 2.93 (measured), 3.02 (calculated) | polish = | opticalprop = Uniaxial (−) | refractive = nω = 1.62, nε = 1.62 (approximated) | birefringence = | pleochroism = None | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = No | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = Sr, Ce, Fe | alteration = | other = | references = <ref name=Mindat /><ref name=GOD /> }} '''Andrianovite''' is a very rare mineral of the eudialyte group,<ref name=Mindat>{{cite web|url=http://www.mindat.org/min-31664.html |title=Andrianovite: Andrianovite mineral information and data |website=Mindat.org |accessdate=2016-03-08}}</ref> with formula Na₁₂(K,Sr,Ce)₆Ca₆(Mn,Fe)₃Zr₃NbSi(Si₃O₉)₂(Si₉O₂₇)₂O(O,H₂O,OH)₅.<ref name=GOD>Khomyakov, A.P., Nechelyustov, G.N., Rastsvetaeva, R.K., and Rozenberg, R.A., 2009. Andrianovite, Na₁₂(K,Sr,Ce)₃Ca₆Mn₃Zr₃Nb(Si₂₅O₇₃)(O,H₂O,OH)₅, a new potassium-rich mineral species of the eudialyte group from the Khibiny alkaline Pluton, Kola Peninsula, Russia. Geology of Ore deposits 50(8), 705–712</ref><ref name=Mindat /> The original formula was extended to show the presence of cyclic silicate groups and silicon at the M4 site, according to the nomenclature of eudialyte group.<ref name=CanMin>Johnsen, O., Ferraris, G., Gault, R.A., Grice, D.G., Kampf, A.R., and Pekov, I.V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785–794</ref> Andrianovite is unique among the eudialyte group in being potassium-rich (other eudialyte-group species with essential K are davinciite and rastsvetaevite<ref name=Mindat />). It is regarded as potassium analogue of kentbrooksite,<ref name=GOD /> but it also differs from it in being oxygen-dominant rather than fluorine-dominant.<ref name=Mindat /> Also, the coordination number of Na in this representative is enlarged from 7 to 9. The name of the mineral honors Russian mathematician and crystallographer Valerii Ivanovich Andrianov.<ref name=GOD />

==Occurrence and association== Andrianovite was discovered in pegmatites of Koashva open pit, Khibiny massif, Kola Peninsula. Russia. It coexists with aegirine, lamprophyllite, lomonosovite, microcline, mosandrite, natrolite, sodalite (silicates) and villiaumite.<ref name=GOD />

==Notes on chemistry== The formula of andrianovite is devoid of some substituting elements and group, the most important being carbonate and chlorine. Minor substituting elements are lanthanum, neodymium, yttrium, titanium, barium, hafnium and aluminium.<ref name=GOD />

==References== {{reflist}}

Category:Cyclosilicates Category:Sodium minerals Category:Potassium minerals Category:Calcium minerals Category:Manganese minerals Category:Zirconium minerals Category:Trigonal minerals Category:Minerals in space group 160

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