Rastsvetaevite

{{Short description|Mineral of the eudialyte group}} {{infobox mineral | name = Rastsvetaevite | category = Silicate mineral, Cyclosilicate | image = Rastsvetaevite-292890.jpg | imagesize = | alt = | caption = Tiny dark pink grains of rastsvetaevite in matrix. Field of view 3 mm. From: Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia | IMAsymbol = Rtv<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 = 64.1b.1.2 | system = Trigonal | class = Ditrigonal pyramidal (3m) <br/>H-M symbol: (3m) | symmetry = ''R''3''m'' | unit cell = a = 14.25, c = 60.97&nbsp;[Å] (approximated); Z&nbsp;=&nbsp;3 | color = Reddish-pink | colour = | habit = irregular grains | twinning = | cleavage = | fracture = Conchoidal | tenacity = Brittle | mohs = 5-6 | luster = Vitreous | streak = White | diaphaneity = Transparent | gravity = 2.86 | density = | polish = | opticalprop = Uniaxial (+) | refractive = nω = 1.60 nε = 1.60 (approximated) | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = <ref name=M /> }} '''Rastsveatevite''' is a rare mineral of the eudialyte group with the chemical formula {{chem2|Na27K8Ca12Fe3Zr6Si4[Si3O9]4[Si9O27]4(O,OH,H2O)6Cl2}}. Its structure is modular.<ref>{{cite journal|last1=Khomyakov |first1=A.P.|last2=Nechelyustov|first2=G.N.|last3=Arakcheeva|first3=A.V.|year=2006|title=Rastsvetaevite, Na₂₇K₈Ca₁₂Fe₃Zr₆Si₄[Si₃O₉]₄[Si₉O₂₇]₄(O,OH,H₂O)₆Cl₂, a new mineral with a modular eudialyte-like structure and crystal-chemical systematics of the eudialyte group|journal=Proceedings of the Russian Mineralogical Society|volume=135|issue=1|pages=49–65}}</ref> It is only the third member of the group after andrianovite and davinciite with essential (site-dominating) potassium.<ref name=M /> Potassium and sodium enter both N4 and M2 sites.<ref>{{Cite journal|last1=Johnsen|first1=O.|last2=Ferraris|first2=G.|last3=Gault|first3=R. A.|last4=Grice|first4=J. D.|last5=Kampf|first5=A. R.|last6=Pekov|first6=I. V.|date=2003-06-01|title=The nomenclature of eudialyte-group minerals|journal=The Canadian Mineralogist|volume=41|issue=3|pages=785–794|doi=10.2113/gscanmin.41.3.785|bibcode=2003CaMin..41..785J |issn=0008-4476}}</ref> The mineral is named after Russian crystallographer Ramiza K. Rastsvetaeva.<ref name=M>Mindat, http://www.mindat.org/min-26586.html</ref>

==Occurrence and association== Rastsvetaevite was originally found in hyperagpaitic (ultra-alkaline) pegmatite at Mt. Rasvumchorr, Khibiny massif, Kola Peninsula, Russia. Associated minerals are aegirine, nacaphite, nepheline, natrite, schcherbakovite, sodalite, villiaumite, and rasvumite.<ref name=M />

==Notes on crystal structure== The ''c'' unit cell parameter in rastsvetaevite is doubled.<ref name=M />

==References== {{reflist}}

Category:Cyclosilicates Category:Sodium minerals Category:Potassium minerals Category:Calcium minerals Category:Iron minerals Category:Zirconium minerals Category:Trigonal minerals Category:Minerals in space group 160 Category:Minerals described in 2003

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