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Sökning: WFRF:(Hålenius Ulf)

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1.
  • Holtstam, Dan, et al. (författare)
  • Delhuyarite-(Ce) – Ce<sub>4</sub>Mg(Fe<sup>3+</sup><sub>2</sub>W)□(Si<sub>2</sub>O<sub>7</sub>)<sub>2</sub>O<sub>6</sub>(OH)<sub>2</sub> – a new mineral of the chevkinite group, from the Nya Bastnäs Fe–Cu–REE deposit, Sweden
  • 2017
  • Ingår i: European journal of mineralogy. - 0935-1221 .- 1617-4011. ; 29:5, s. 897-905
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Delhuyarite-(Ce) is a new mineral (IMA no. 2016-091) with ideal formula Ce<sub>4</sub>Mg(Fe<sup>3+</sup><sub>2</sub>W)□(Si<sub>2</sub>O<sub>7</sub>)<sub>2</sub>O<sub>6</sub>(OH)<sub>2</sub>. It is named after Juan and Fausto de Elhuyar (Delhuyar), chemists and metallurgists, who in 1783 isolated tungsten metal for the first time.  Associated minerals in the only known sample, from the Nya Bastnäs Fe–Cu–REE deposit (Västmanland, Sweden), include cerite-(Ce), tremolite‒actinolite, percleveite-(Ce), bastnäsite-(Ce), ferriallanite-(Ce), törnebohmite-(Ce), magnetite, chalcopyrite, quartz and scheelite. Delhuyarite-(Ce), which forms subhedral crystals up to 0.3mm long, is brown–black with a dark brown streak and translucent with an adamantine lustre. It is pleochroic in black to rust red and optically biaxial (-). Calculated density and mean refractive index are 5.20 g·cm<sup>-3</sup> and 1.94, respectively. Chemical analyses (electron microprobe) gave (in wt%) La<sub>2</sub>O<sub>3</sub> 14.58, Ce<sub>2</sub>O<sub>3</sub> 23.29, Pr<sub>2</sub>O<sub>3 </sub>1.89, Nd<sub>2</sub>O<sub>3</sub> 6.13, Sm<sub>2</sub>O<sub>3</sub> 0.74, Gd<sub>2</sub>O<sub>3</sub> 0.37, Dy<sub>2</sub>O<sub>3</sub> 0.03, Er<sub>2</sub>O<sub>3</sub> 0.04, Yb<sub>2</sub>O<sub>3</sub> 0.12, Y<sub>2</sub>O3 0.22, CaO 0.76, Fe<sub>2</sub>O<sub>3</sub> 12.86, MgO 2.43, Al<sub>2</sub>O<sub>3</sub> 0.73, SiO<sub><em>2</em></sub> 18.16, TiO<sub>2</sub> 0.09, WO<sub>3</sub> 15.53, H<sub>2</sub>O<sub>calc</sub> 1.33, F 0.05, Cl 0.03, O=(F, Cl) 0.03, sum 99.35, corresponding to an empirical formula: (Ce<sub>1.89</sub>La<sub>1.19</sub>Nd<sub>0.48</sub>Pr<sub>0.15</sub>Sm<sub>0.06</sub>Gd<sub>0.03</sub>Y<sub>0.03</sub>Ca<sub>0.18</sub>)<sub>Σ4.01</sub>(Fe<sup>3+</sup><sub>2.14</sub>W<sub>0.89</sub>Mg<sub>0.80</sub>Al<sub>0.19</sub>Ti<sub>0.02</sub>)<sub>Σ4.04</sub>Si<sub>4.01</sub>O<sub>20</sub>(OH<sub>1.96</sub>F<sub>0.04</sub>)<sub>Σ2</sub>, based on 22 O atoms per formula unit (apfu). The presence of H<sub>2</sub>O is confirmed by IR-spectroscopy, from a strong absorption band at 3495 cm<sup>-1</sup>. Delhuyarite-(Ce) is monoclinic, space group <em>C</em>2/<em>m</em>, with unit-cell parameters <em>a</em> =13.6020(6)Å, <em>b</em> = 5.7445(3)Å, <em>c</em> = 10.9996(5)Å, <em>β </em>= 100.721(4)°, V = 844.47 (6)Å<sup>3</sup> and Z = 2 (data for natural crystal). The crystal structure was refined to an R1 index of 3.9% (natural crystal) and 1.8% (annealed). Delhuyarite-(Ce) has the same structural topology as chevkinite subgroup minerals, <em>e.g</em>. chevkinite-(Ce). It is the only mineral of the group with a significant content of W<sup>6+</sup> = 0.89 apfu. In delhuyarite-(Ce), Mg is dominant at the M1 site as in polyakovite-(Ce); the composition of the M2, M3 and M4 sites is [(Fe<sup>3+</sup>2W)□], with M2 being 50% vacant.</p>
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  • Biagion, Cristian, et al. (författare)
  • The crystal structure of turneaureite, Ca<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>Cl, the arsenate analog of chlorapatite and its relationships with the arsenate apatites johnbaumite and svabite
  • 2017
  • Ingår i: American Mineralogist. - 0003-004X .- 1945-3027. ; 102, s. 1981-1986
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The crystal structure of turneaureite, ideally Ca<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>Cl, was studied using a specimen from the Brattfors mine, Nordmark, Värmland, Sweden, by means of single-crystal X-ray diffraction data. The structure was refinedto R1 = 0.017 on the basis of 716 unique reflectios with F<sub>o</sub> &gt; 4σ(F<sub>o</sub>) in the <em>P</em>6<sub>3</sub>/<em>m</em> space group, with unit-cell parameters <em>a</em> = 9.9218(3), <em>c </em>= 6.8638(2) Å, V = 585.16(4) Å<sup>3</sup>. The chemical composition of the sample, determined by electron-microprobe analysis, is (in wt%; average of 10 spot analyses): SO<sub>3</sub> 0.22, P<sub>2</sub>O<sub>5</sub> 0.20, V<sub>2</sub>O<sub>5</sub> 0.01, As<sub>2</sub>O<sub>5</sub> 51.76, SiO<sub>2</sub> 0.06, CaO 41.39, MnO 1.89, SrO 0.12, BaO 0.52, PbO 0.10, Na2O 0.02, F 0.32, Cl 2.56, H<sub>2</sub>O<sub>calc</sub> 0.58, O(≡F+Cl) –0.71, total 99.04. On the basis of 13 anions per formula unit, the empirical formula corresponds to (Ca<sub>4.82</sub>Mn<sub>0.17</sub>Ba<sub>0.02</sub>Sr<sub>0.01</sub>)∑<sub>5.02</sub> (As<sub>2.94</sub>P<sub>0.02</sub>S<sub>0.02</sub>Si<sub>0.01</sub>)<sub>∑2.99</sub>O<sub>12</sub>[Cl<sub>0.47</sub>(OH)<sub>0.42</sub>F<sub>0.11</sub>]<sub>∑1.00</sub>.Turneaureite is topologically similar to the other members of the apatite supergroup: columns of face-sharing M1 polyhedra running along c are connected through TO<sub>4</sub> tetrahedra with channels hosting M2 cations and X anions. Owing to its particular chemical composition, the studied turneaureite can be considered as a ternary calcium arsenate apatite; consequently it has several partially filledanion sites within the anion columns. Polarized single-crystal FTIR spectra of the studied sample indicate stronger hydrogen bonding and less diverse short-range atom arrangements around (OH) groups in turneaureite as compared to the related minerals johnbaumite and svabite. An accurate knowledge of the atomic arrangement of this apatite-remediation mineral represents an improvement in our understanding of minerals able to sequester and stabilize heavy metals such as arsenic in polluted areas.</p>
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  • Biagioni, Cristian, et al. (författare)
  • Nuove specie mineralogiche Italiane
  • 2019
  • Ingår i: Rivista Mineralogica Italiana. ; 43:4, s. 256-262
  • Tidskriftsartikel (populärvet., debatt m.m.)
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9.
  • Biagioni, Cristian, et al. (författare)
  • Nuovi minerali Italiana - La approvazioni 2017
  • 2018
  • Ingår i: Revista Mineralogica Italiana. - Milano, Italy. - 0391-9641. ; 42:3, s. 190-197
  • Tidskriftsartikel (populärvet., debatt m.m.)
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10.
  • Biagioni, Cristian, et al. (författare)
  • The crystal structure of svabite, Ca<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>F, an arsenate member of the apatite supergroup
  • 2016
  • Ingår i: American Mineralogist. - 0003-004X .- 1945-3027. ; 101, s. 1750-1755
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The crystal structure of svabite, ideally Ca<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>F, was studied using a specimen from the Jakobsberg mine, Värmland, Sweden, by means of single-crystal X‑ray diffraction data. The structure was refined to <em>R</em><sub>1</sub> = 0.032 on the basis of 928 unique reflections with <em>F</em><sub>o</sub> &gt; 4s(<em>F</em><sub>o</sub>) in the <em>P</em>6<sub>3</sub>/<em>m </em>space group, with unit-cell parameters <em>a </em>= 9.7268(5), <em>c </em>= 6.9820(4) Å, <em>V </em>= 572.07(5) Å3. The chemical composition of the sample, determined by electron-microprobe analysis, is (in wt%, average of 10 spot analyses): SO<sub>3</sub> 0.49, P<sub>2</sub>O<sub>5</sub> 0.21, V<sub>2</sub>O<sub>5</sub> 0.04, As<sub>2</sub>O<sub>5</sub> 51.21, SiO<sub>2</sub> 0.19, CaO 39.31, MnO 0.48, SrO 0.03, PbO 5.19, Na<sub>2</sub>O 0.13, F 2.12, Cl 0.08, H<sub>2</sub>O<sub>calc</sub> 0.33, O (≡ F+Cl) –0.91, total 98.90. On the basis of 13 anions per formula unit, the empirical formula corresponds to (Ca<sub>4.66</sub>Pb<sub>0.16</sub>Mn<sub>0.04</sub>Na<sub>0.03</sub>)<sub>Σ4.89</sub>(As<sub>2.96</sub>S<sub>0.04</sub>Si<sub>0.02</sub>P<sub>0.02</sub>)<sub>Σ3.04</sub>O<sub>12</sub>[F<sub>0.74</sub>(OH)<sub>0.24</sub>Cl<sub>0.01</sub>]. Svabite is topologically similar to the other members of the apatite supergroup: columns of face-sharing <em>M</em>1 polyhedra running along <strong>c </strong>are connected through <em>T</em>O<sub>4</sub> tetrahedra with channels hosting <em>M</em>2 cations and <em>X </em>anions. The crystal structure of synthetic Ca<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>F was previously reported as triclinic. On the contrary, the present refinement of the crystal structure of svabite shows no deviations from the hexagonal symmetry. An accurate knowledge of the atomic arrangement of this apatite-remediation mineral represents an improvement in our understanding of minerals able to sequester and stabilize heavy metals such as arsenic in polluted areas.</p>
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