Record details

    Allanite-(Nd), CaNdAl2Fe2+(SiO4)(Si2O7)O(OH), a new mineral from Askagen, Sweden.
    Cempírek, Jan
    Čtvrtlík, Radim
    Filip, Jan
    Novák, Milan
    Škoda, Radek
    Veselovský, František
Publication type
    článek v periodiku
Source title - serial
    American Mineralogist
    Roč. 97, č. 5-6
Thesaurus term
    Epidote supergroup
Abstract (in english)
   Allanite-(Nd), ideally CaNdAl2Fe2+(SiO4)(Si2O7)O(OH), the Nd-analog of allanite-(Ce), occurs in the Askagen pegmatite, central Sweden. It forms fine-grained aggregates within altered thalenite-(Y). The other associated minerals include: iimoriite-(Y), keiviite-(Y), allanite-(Y), and tengerite-(Y). Allanite-(Nd) is biaxial (-); with refractive indices ? = 1.723(5), ? = 1.754(7), ? = 1.772(5), and measured 2V = 82°(? 3°). Larger fragments of allanite-(Nd) are moderately pleochroic (? = pale grayish-brown, ? = grayish-brown); small fragments are colorless. Allanite-(Nd) is monoclinic, space group P2(1)/m, with the following unit-cell parameters: a = 8.8897(5), b = 5.7308(2), c = 10.1010(6) angstrom, ? = 115.166(7)°, V = 465.75(4) angstrom(3), Z = 2. The strongest five peaks from the X-ray powder diffraction patterns [d (angstrom)(I)(hkl)] are: 3.51(46)((2) over bar 11), 2.89(100)((1) over bar 13), 2.87(45)(020), 2.70(60)(120), 2.61(60)((3) over bar 11). Allanite-(Nd) has a density of 3.98
    g/cm3, vitreous luster, grayish-brown streak, and the Mohs hardness is ca. 6. It is brittle, with imperfect cleavage, and conchoidal fracture. The Mossbauer spectroscopy revealed Fe3+/Fe-101 ratio of 0.27 in the type sample. The refined empirical formula of the crystal used for the structure determination is: Al(Ca0.957Mn0.043)?1.000(Nd0.337Ca0.154Sm0.131Ce0.125Y0.112Gd0.062Pr0.051Dy0.016La0.007Er0.005)?1.000 M1(Al0.860Fe0.1403+)?1.000 M2AlM3 (Fe2+0.760Al0.112Fe3+0.070Mg0.058)?1.000 T1,2,3Si3O11.978(OH)1.032. The allanite-(Nd) was approved by CNMNC (IMA 2010-060).
    Moravské zemské muzeum Brno
Contributor code
Source format
Import date
    27. 4. 2014