Time filter

Source Type


Miyawaki R.,National Museum of Nature and Science | Momma K.,National Museum of Nature and Science | Yokoyama K.,National Museum of Nature and Science | Shigeoka M.,National Museum of Nature and Science | And 4 more authors.
Canadian Mineralogist | Year: 2015

Mn-bearing hellandite-(Y) occurs as pinkish yellow granular crystals (up to sub mm) in the Sc-rich granite pegmatite at Heftetjern, Tørdal, Telemark, Norway. Associated minerals are quartz, albite, Sc- and Ce-bearing epidote, hingganite-(Y), and an undetermined Ca-bearing hingganite-related mineral. Electron microprobe analyses give an empirical formula as Ca1.34Mn1.07Y2.75Ce0.02Nd0.02Sm0.01Gd0.01Dy0.05Er0.05Yb0.15Al0.94Fe0.08Si3.99B4.33O22.00 (OH)2.00 on the basis of Al+Fe+Si = 5 and 24 anions per formula unit. The lattice parameters were refined from diffraction data obtained using a Gandolfi camera with an imaging plate and Ni filtered CuKα; a 18.693(17), b 4.651(3), c 10.178(7) A, β = 111.37(6)°, V 824.1(10) A3. The crystal structure was refined from single-crystal XRD data obtained with a CCD-diffractometer and graphite-monochromated MoKα. The refinement with anisotropic atomic displacement parameters converged to R1 = 0.0269 for 1567 reflections [I > 2σ(I)] and 0.0318 for all 1768 reflections, resulting in the structural formula M3(Ca0.56Mn0.44)2 M4(Y0.43 Ca0.23Ln0.14 0.20)2 M2(Y0.94Ln0.06)2 M1(Al0.92Fe0.08)Si4B4O21.21 (OH)2.79. In this hellandite-(Y), Mn2+ replaces Ca2+ at the M3 site and there is a significant vacancy at the M4 site. The T site is vacant, and, instead, the O5 position is occupied by (OH)-.

Bos D.,PO Box 32 | Bos D.,University of Groningen | Ydenberg R.,Wageningen University | Ydenberg R.,Simon Fraser University
Wildlife Biology | Year: 2011

Muskrats Ondatra zibethicus are considered a pest species in the Netherlands, and a year-round control programme is in effect. Currently, the agency responsible for the management of muskrat populations in the Netherlands (the LCCM) is preparing for field studies to compare alternative strategies of control. In order to decide on the specific design of such field studies, a population dynamic model was built. The model compares the current management strategy with alternatives in which the effort is focused in space or in time. The model allows us to prioritise future research questions. The major gaps in knowledge at this moment are: 1) insight into the costs of harvesting at different harvest rates, and 2) the relationship between population density on the one hand and (financial damage or) safety risk on the other hand. We suggest continuing the current management, and to test our hypothesis that intensifying harvest will lead to lower numbers of animals killed in the medium term than more extensive harvest rates. The muskrat control programme offers excellent opportunities for applied biological studies of which the benefits are likely to outweigh the costs. © Wildlife Biology, NKV.

Kolitsch U.,Mineralogisch Petrographische Abt. | Kristiansen R.,PO Box 32 | Raade G.,University of Oslo | Tillmanns E.,University of Vienna
European Journal of Mineralogy | Year: 2010

Heftetjernite,ideally ScTaO4, is a new scandium mineral from the Heftetjern pegmatite, T0ℝ, Telemark, Norway. In the type specimen, it occurs as minute, elongate tabular, very dark brown crystals in a single small void in albite. Other associated minerals are fluorite, muscovite, altered milarite, a metamict, dark greyish brown mineral of the pyrochlore-microlite group, and an unidentified, orange-brown, tabular, nearly X-ray amorphous Ti-Y-Ta-Nb-mineral. Electron-microprobe analysis yielded the empirical formula (Sc0.64Sn0.13Mn0.12Fe0.08Ti 0.06)σ1.03(Ta0.69Nb0.30) σ0.99O4 which clearly demonstrates the charge-balanced substitution scheme 2Sc3+ = (Sn,Ti)4+ + (Mn,Fe)2+. Themineral crystallises in the wolframite structure type, with space group P2/c and a= 4.784(1), b= 5.693(1), c = 5.120(1) Å , β = 91.15(3)-B, V = 139.42(5) Å 3 (Z = 2). A synthetic equivalent is known. Strongest lines in the calculated X-ray powder diffraction pattern of heftetjernite are [d in Å (I) (hkl)]: 3.000 (100) (11-1), 2.9570 (97) (111), 3.662 (53) (110), 2.4877 (34) (02-1), 4.783 (33) (100), 3.807 (32) (01-1). The crystal structure was refined to R(F)= 1.39%from single-crystal X-ray diffraction data (293 K). It is based on two types of edge-sharing, distorted octahedra occupied predominantly by Sc and Ta, respectively. Heftetjernite is translucent to transparent, with a dark brownish (with a reddish hue) streak and adamantine lustre. It is brittle, has a perfect {010} cleavage, irregular fracture and a Mohs hardness estimated to be around 4.5 by comparison to ferberite; Dx = 6.44 g/ cm3 (from crystal-structure analysis). Optically, the mineral is biaxial with an unknown optical sign, weakly pleochroic (yellowish brown with a reddish tint to reddish brown), with no observable dispersion. A mean refractive index of 2.23 was calculated from the Gladstone-Dale relationship using the X-ray density. Heftetjernite is named after its type locality. The mineral is compared with synthetic ScTaO 4, ScNbO4, iwashiroite-(Y) and formanite-(Y) (both nominally YTaO4), and some comments are made on the relation to Sc-bearing ixiolite. © 2010 E. Schweizerbart'sche Verlagsbuchhandlung.

Oberti R.,CNR Institute of Geosciences and Earth Resources | Boiocchi M.,University of Pavia | Hawthorne F.C.,University of Manitoba | Kristiansen R.,PO Box 32
Mineralogical Magazine | Year: 2014

A second occurrence of ferri-fluoro-leakeite has been identified in the Bratthagen nepheline syenite pegmatite (Vestfold County, Norway). With respect to the holotype found at the Verkhnee Espe deposit (Akjailyautas Mountains, Kazakhstan; Cámara et al., 2010), it is closer to the ideal composition because of its larger Li and Mg contents and the absence of an oxo-component; however, it has a significant Zn content (0.29 a.p.f.u.). The ideal formula of ferri-fluoro-leakeite is ANaBNa2 C(Mg2Fe3+ 2Li)TSi8O22 WF2 and the empirical formula derived from electron-microprobe analysis and single-crystal structure refinement for the sample used here is A(Na0.68K0.32)=1.00 BNa2.00 C(Mg1.69Mn2+ 0.25Fe2+ 0.24Zn 0.29Al0.23Fe3+ 1.50Ti0.02Li0.78)=5.00 TSi8O22 W(F1.59(OH)0.41)=2.00. Unitcell data are a = 9.788(2), b = 17.826(3), c = 5.282(1) Å, β = 104.195(5)°, V = 893.5 (3) Å3, Z = 2. Crystal-chemical analysis shows that Li is ordered at the M(3) site and Zn is ordered mainly at the M(2) site, confirming previous findings for Li-bearing amphiboles. The new data also make quantification of the oxo component in Na amphiboles possible. © 2014 Mineralogical Society.

Grice J.D.,Canadian Museum of Nature | Kristiansen R.,PO Box 32 | Friis H.,University of Oslo | Rqwe R.,Canadian Museum of Nature | And 4 more authors.
Canadian Mineralogist | Year: 2013

Ferrochiavennite is a new beryllium silicate zeolite with chemical composition close to CaM1-2FeSi5Be2O 13(OH)2,2H2O. It is described from two syenite pegmatite localities in Norway: Blafjell, Langangen, Telemark, and the AS Granit larvikite quarry, Tvedalen, Vestfold. The mineral is monoclinic, P2 /c, with a 8.759(5), b 4.864(2), c 31.258(6) Å, p 90.31(6)°, V 1331.7(6) Å3, and Z = 4. The crystal structure was refined to R1 = 0.048 for 3651 observed reflections. The zeolite structure is isostructural with chiavennite, consisting of intersecting channels of nine-, six-, five-, and four-fold rings. The strongest eight reflections of the X-ray powder-diffraction pattern [d(obs.) in Å (I) (hkl)] are: 15.555 (100) (002), 4.104 (29) (11̄2, 112), 3.938 (36) (11̄3, 113), 3.909 (60) (008), 3.820 (30) (2̄04, 204), 3.251 (66) (017, 210, 2̄11), 3.186 (27) (2̄12, 212), 2.884 (64) (2̄15, 215). The mineral is biaxial (+) with refractive indices a 1.583(1), β 1.589(1), γ 1.602(1), measured at 590 nm. 2V (meas.) = 62(4)° from extinction curves 2V = 76(5)°; 2V (calc.) = 69°. The optical orientation is X ∼ a, Y ∼ c, and Z ∼ b. The Mohs hardness is ∼ 3; D(meas.) = 2.67(2) and D(calc.) = 2.709 g/cm3..

Discover hidden collaborations