{{infobox mineral | name = Raslakite | category = Silicate mineral | image = Raslakite.jpg | imagesize = | alt = | caption = Red glassy raslakite in nepheline-syenite from the type locality: Karnasurt Mountain, Lovozero Massif, Northern Region, Russian Federation. | formula = {{chem2|Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)(Si25O73)(OH,H2O)3(Cl,OH)}} (original form) | IMAsymbol = Rsk<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 = | system = Trigonal | class = Pyramidal (3) <br/>H-M symbol: (3) | symmetry = ''R''3 | unit cell = a = 14.23, c = 30.02 [Å]; Z = 3 | color = Brownish-red | colour = | habit = Grains | twinning = | cleavage = Imperfect | fracture = Conchoidal | tenacity = Brittle | mohs = 5 | luster = Vitreous | streak = White | diaphaneity = Transparent | gravity = 2.95 (measured) | density = | polish = | opticalprop = Uniaxial | refractive = nω = 1.61, nε = 1.61 (approximated) | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = <ref name=M /><ref name=Ch /> }} '''Raslakite''' is a rare mineral of the eudialyte group with the chemical formula {{chem2|Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)SiO(Si9O27)2(Si3O9)2(OH,H2O)3(Cl,OH)}}. This formula is based on the original one, and is extended to show the presence of cyclic silicate groups. The additional silicon and oxygen shown in separation from the cyclic groups (in parentheses) are in fact connected with two 9-fold rings.<ref name=M>Mindat, Raslakite, http://www.mindat.org/min-25687.html</ref> The mineral has lowered symmetry (space group ''R''3, instead of more specific for the group ''R''3''m'' one),<ref name=Ch>Chukanov, N.V., Pekov, I.V., Zadov, A.E., Korovushkin, V.V., Ekimenkova, I.A., and Rastsvetaeva, R.K., 2003: Ikranite, {{chem2|(Na,H3O)15(Ca,Mn,REE)6Fe(3+)2Zr3([],Zr)([],Si)Si24O66(O,OH)6Cl*nH2O}} and raslakite {{chem2|Na15Ca3Fe3(Na,Zr)3Zr3(Si,Nb)(Si25O73)(OH,H2O)3(Cl,OH)}}-new eudialyte-group minerals from the Lovozero massif, Kola Peninsula. Zapiski Vserossiyskogo Mineralogicheskogo Obshchestva 132(5), 22–33 (in Russian, with English abstract)</ref> similarly to some other eudialyte-group members: aqualite, labyrinthite, oneillite and voronkovite.<ref name=M /> The specific feature of raslakite is, among others, the presence of sodium and zirconium at the M2 site. Raslakite was named after Raslak Cirques located nearby the type locality.<ref name=Ch />
==Occurrence and association== Raslakite was discovered, together with ikranite, in peralkaline pegmatites of the Mt. Karnasurt, Lovozero massif, Kola Peninsula, Russia. Raslakite is associated with aegirine, fluorcaphite, kazakovite, lamprophyllite, microcline, nepheline, and terskite.<ref name=Ch />
==Notes on chemistry== Beside main elements given in the formula, raslakite contains some potassium, strontium, manganese, magnesium, cerium, titanium, and aluminium, with minor amounts of lanthanum and hafnium.<ref name=Ch />
==Notes on crystal structure== The M(1) site in raslakite is split into two sub-sites, where Fe and Ca are located. The M(2) site is occupied by sodium, manganese (both with coordination number 5), and zirconium (tetrahedral coordination).<ref name=Ch />
==References== {{reflist}}
Category:Cyclosilicates Category:Sodium minerals Category:Calcium minerals Category:Iron minerals Category:Zirconium minerals Category:Niobium minerals Category:Trigonal minerals Category:Minerals in space group 146 Category:Minerals described in 2002
{{silicate-mineral-stub}}