Détail de la notice
Titre du Document
Ikranite, (Na, H3O)15(Ca, Mn, REE)6Fe3+2Zr3(□, Zr)(□Si)Si24O66(O, OH)6Cl . nH2O and raslakite Na15Ca3Fe3(Na, Zr)3Zr3(Si, Nb) (Si25O73)(OH, H2O)3(Cl, OH): The new eudialyte-group minerals from Lovozero Massif, Kola Peninsula
Auteur(s)
CHUKANOV N. V. ; PEKOV I. V. ; ZADOV A. E. ; ...
Résumé
Ikranite and raslakite were discovered in two peralkaline pegmatites at the Karnasurt Mt of Lovozero alkaline massif, in associations with aegirine, microcline, lorenzenite, nepheline, lamprophyllite, murmanite, arfvedsonite (for ikranite) and with microcline, aegirine, nepheline, lamprophyllite, kazakovite, terskite, fluorcaphite (for raslakite). The new minerals form brownish-yellow (ikranite) or brownish-red (raslakite) grains up to 2-3 cm in size. Brittle, cleavage non-perfect, Mobs' hardness 5. Both are optically positive. Ikranite is often weakly biaxial, raslakite is uniaxial: ω = 1.612 (1) and 1.608; ε = 1.615 and 1.611; Dmeas = 2.82 (3) and 2.95 (1) g/cm3, Dcalc = 2.83 and 2.945 g/cm3, respectively. Both minerals are trigonal, space groups R3m and R3, a = 14.167 (2) and 14.229 (7), c = = 30.081 (2) and c = 30.019 (15) Å; V = 5228.5 and 5263.5 Å3, respectively; for both R = 0.037. Ikranite differs from all other eudialyte-group minerals by the prevailing of vacancies in the sites M (3) and M (4) at the centers of the 9-membered Si-rings and by the strong predominance of [6]Fe3+ over [4]Fe2+ in the M (2) position linking 6-membered Ca-rings. In ikranite Na is partly substituted by H3O; in raslakite M (1) is transformed into two independent sites M (1,1) and M (1,2) occupied mainly by Fe and Ca, respectively. The position M (2) is stati
Editeur
Nauka
Identifiant
ISSN : 0869-6055
Source
Zapiski Vserossijskogo mineralogičeskogo obŝestva A. 2003, vol. 132, n° 5, pp. 22-33 [12 pages]
Langue
Russe
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