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Sökning: WFRF:(Bindi Luca)

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4.
  • Bonazzi, Paola, et al. (författare)
  • Multi-analytical approach to solve the puzzle of an allanite-subgroup mineral from Kesebol, Vastra Gotaland, Sweden
  • 2009
  • Ingår i: American Mineralogist. - 0003-004X .- 1945-3027. ; 94:1, s. 121-134
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Dark-brownish. euhedral crystals of an "allanite-like" mineral occur in a hematite-impregnated Mn-silicate rock at Kesebol, Vastra Gotaland, Sweden, associated with gasparite-(Ce), chernovite-(Y), rhodonite, andradite, manganoan calcite, and quartz. A structural study was carried out on single crystals-untreated, heated in air, and heated under inert atmosphere-combined with Mossbauer spectroscopy and TEM investigation. In all the untreated crystals the mean &lt; M3-O &gt; distance indicates that Me2+(Me = Mn, Fe) prevails at this site (&lt; M3-O &gt; in the range 2.169-2.180 angstrom), in contrast with chemical data obtained by EPMA that yield a simplified formula Ca(REE2/33+square(1/3))Me-3(3+)(SiO4)(Si2O7) O(OH), when normalized to Si = 3.00 apfu. Moreover, when a crystal is heated in air, all geometrical and structural variations indicate the development of an oxidation-dehydrogenation reaction, thus confirming that M3 is occupied by divalent cations before heating. The corresponding dehydrogenation is confirmed by a dramatic lengthening of the donor-acceptor distance. A crystal was annealed under inert atmosphere to verify possible effects of radiation damage on the polyhedral volumes. After prolonged annealing at 700 C, a slight decrease of the unit-cell parameters is observed, suggesting restoring of crystallinity from a "partially metamict" state. Nonetheless, even in the annealed crystal, the &lt; M3-O &gt; distance is still consistent with a dominance of divalent cations at the M3 site. For all the examined crystals, structural data point to an octahedral cation population as follows: M1 = (Me3+, Al); M2 = (Al, Me3+). M3 = (Me2+, Me3+). This assumption is also in agreement with the Mossbauer spectrum, which was fitted to two Lorentzian quadrupole doublets for Fe3+ and one for Fe2+. Values of the isomer shifts (0.36 and 0.37 mm/s for Fe3+; 1.11 mm/s for Fe2+) and the quadrupole splitting (1.96 and 1.02 for Fe3+; 1.90 for Fe2+) show that Fe2+ (similar to 12% of the total iron) is located in M3, while Fe3+ occupies M I and, to lesser extent, M2. TEM-EDS investigations have revealed chemical heterogeneities related to different degree of radiation damage. In particular, areas showing poor crystallinity are relatively enriched in Si and O with respect to the highly crystalline areas, thus suggesting that EPMA chemical data are biased by the presence of metamict areas enriched in SiO2 and likely in H2O. EPMA data were therefore corrected for the excess of silica. The cation population after correction is in keeping with the structural and spectroscopic data. Disregarding minor substitutions, the ideal chemical formula for the epidote-group mineral from Kesebol is CaREEFe3+AlMn2+(Si2O7)(SiO4)O(OH), which is related to ferriallanite-(Ce) by the substitutional vector (M3)(Mn2+) -&gt; M3 (Fe2+).</p>
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5.
  • 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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6.
  • Holtstam, Dan, et al. (författare)
  • Ulfanderssonite-(Ce), a new Cl-bearing <em>REE</em> silicate mineral species from the Malmkärra mine, Norberg, Sweden
  • 2017
  • Ingår i: European journal of mineralogy. - 0935-1221 .- 1617-4011. ; 29:6, s. 1015-1026
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Ulfanderssonite-(Ce) is a new mineral (IMA 2016-107) from the long-abandoned Malmkärra iron mine, one of the Bastnäs-type Fe-rare earth element (<em>REE</em>) deposits in the Bergslagen ore region, central Sweden. It is named for Ulf B. Andersson, a Swedish geologist and petrologist. In the type specimen, the mineral occurs with västmanlandite-(Ce), bastnäsite-(Ce), phlogopite, talc, magnetite, pyrite, fluorbritholite-(Ce) and scheelite. Ulfanderssonite-(Ce) forms pinkish, translucent subhedral grains, 100–300 mm, in aggregates up to 2 mm. Fracture is uneven, and there is an indistinct cleavage parallel (001). Mohs' hardness is 5−6, <em>d</em><sub>calc</sub>= 4.97 g·cm<sup>-3</sup>. Optically, ulfanderssonite-(Ce) is nonpleochroic, biaxial negative, with 2<em>V</em><sub>meas </sub>=55° and <em>n</em><sub>calc</sub>=1.82. The ideal composition is Ce<sub>15</sub>CaMg<sub>2</sub>(SiO<sub>4</sub>)<sub>10</sub>(SiO<sub>3</sub>OH)(OH,F)<sub>5</sub>Cl<sub>3</sub>. EMP and LA-ICP-MS chemical analyses yielded (in wt%) La<sub>2</sub>O<sub>3</sub> 11.87, Ce<sub>2</sub>O<sub>3</sub> 30.98, Pr<sub>2</sub>O<sub>3</sub> 3.99, Nd<sub>2</sub>O<sub>3</sub> 17.14, Sm<sub>2</sub>O<sub>3</sub> 2.81, Eu<sub>2</sub>O<sub>3</sub> 0.18, Gd<sub>2</sub>O<sub>3</sub> 1.15, Dy<sub>2</sub>O<sub>3</sub> 0.30, Tb<sub>2</sub>O<sub>3</sub> 0.10, Y<sub>2</sub>O<sub>3</sub> 1.11, CaO 2.26, FeO 0.02, MgO 1.97, P<sub>2</sub>O<sub>5</sub> 0.08 SiO<sub>2</sub> 19.13, H<sub>2</sub>O<sub>calc</sub> 1.07, F 1.09, Cl 2.89, O=(F, Cl) -1.10, sum 97.04. The five strongest powder X-ray diffraction lines are [<em>I</em> (%) <em>d</em><sub>obs</sub>(Å) (<em>hkl</em>)]: 100 2.948 (-421), 47 2.923 (204), 32 2.660 (-225), 26 3.524 (40-1), 25 1.7601 (6-23). Ulfanderssonite-(Ce) is monoclinic, <em>Cm</em>, with <em>a </em>=14.1403(8), <em>b</em> = 10.7430(7), <em>c </em>=<em> </em>15.498(1) Å, β<em> = </em>106.615(6)° and <em>V </em>= 2256.0(2) Å<sup>3</sup><em> </em>for<em> Z </em>= 2<em>. </em>The crystal structure has been solved by direct methods and refined to R<sub>1</sub> = 2.97% for 5280 observed reflections. It consists of a regular alternation of two layers, designated <em>A</em> and <em>B</em>, along the <em>c</em>-axis: <em>A</em> (ca. 9 Å thickness), with composition [(Ce<sub>8</sub>Ca)MgSi<sub>7­</sub>O<sub>22</sub>(OH,F)<sub>4</sub>]<sup>8+</sup>, and <em>B</em> (ca. 6.5 Å), with composition [Ce<sub>7</sub>Mg­Si<sub>4</sub>O<sub>21</sub>(OH,F)<sub>2</sub>Cl<sub>3</sub>]<sup>8-</sup>; the <em>A</em> layer is topologically and chemically closely related to cerite-(Ce). A FTIR spectrum shows strong absorption in the region 2850−3650 cm<sup>-1</sup>, related to the presence of O-H stretching bands. Ulfanderssonite-(Ce) is interpreted as a primary mineral at the deposit, along with the more common fluorbritholite-(Ce), formed by a magmatic-hydrothermal fluid with REE, Si, F and Cl ion complexes reacting with dolomite marble. The presence of ulfanderssonite-(Ce) is direct evidence of a Cl-rich mineral-forming aqueous solution, normally not reflected in the composition of skarn minerals in Bastnäs-type deposits.</p>
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7.
  • Holtstam, Dan, et al. (författare)
  • Ulfanderssonite-(Ce), a new Cl-bearing REE silicate mineral species from the Malmkärra mine, Norberg, Sweden
  • 2017
  • Ingår i: European journal of mineralogy. - 0935-1221 .- 1617-4011. ; 29:6, s. 1015-1026
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Ulfanderssonite-(Ce) is a new mineral (IMA 2016-107) from the long-abandoned Malmkärra iron mine, one of the Bastnäs-type Fe-rare earth element (REE) deposits in the Bergslagen ore region, central Sweden. It is named for Ulf B. Andersson, a Swedish geologist and petrologist. In the type specimen, the mineral occurs with västmanlandite-(Ce), bastnäsite-(Ce), phlogopite, talc, magnetite, pyrite, fluorbritholite-(Ce) and scheelite. Ulfanderssonite-(Ce) forms pinkish, translucent subhedral grains, 100-300 mu m, in aggregates up to 2 mm. Fracture is uneven, and there is an indistinct cleavage parallel (001). Mohs' hardness is 5-6, D-calc = 4.97 g cm(-3). Optically, ulfanderssonite-(Ce) is nonpleochroic, biaxial negative, with 2V(meas) = 55 degrees and n(calc) = 1.82. The ideal composition is Ce15CaMg2(SiO4)(10)(SiO3OH)(OH,F)(5)Cl-3. Electron microprobe and LA-ICP-MS chemical analyses yielded (in wt%) La2O3 11.87, Ce2O3 30.98, Pr2O3 3.99, Nd2O3 17.14, Sm2O3 2.81, Eu2O3 0.18, Gd2O3 1.15, Dy2O3 0.30, Tb2O3 0.10, Y2O3 1.11, CaO 2.26, FeO 0.02, MgO 1.97, P2O5 0.08, SiO2 19.13, H2Ocalc 1.07, F 1.09, Cl 2.89, O=(F, Cl) -1.10, sum 97.04. The five strongest powder X-ray diffraction lines are [I(%) d(obs) (angstrom) (hkl)]: 100 2.948 (- 421), 47 2.923 (204), 32 2.660 (- 225), 26 3.524 (40-1), 25 1.7601 (6-23). Ulfanderssonite-(Ce) is monoclinic, Cm, with a = 14.1403(8), b = 10.7430(7), c = 15.498(1) angstrom, b = 106.615(6)degrees and V = 2256.0 (2) angstrom 3 for Z = 2. The crystal structure has been solved by direct methods and refined to R-1 = 2.97% for 5280 observed reflections. It consists of a regular alternation of two layers, designated A and B, along the c-axis: A (ca. 9 angstrom thickness), with composition [(Ce8Ca) MgSi7O22(OH, F) 4](8+), and B (ca. 6.5 angstrom), with composition [Ce7MgSi4O21(OH, F)(2)Cl-3](8); the A layer is topologically and chemically closely related to cerite-(Ce). A FTIR spectrum shows strong absorption in the region 2850-3650 cm(-1), related to the presence of OH stretching bands. Ulfanderssonite-(Ce) is interpreted as a primary mineral at the deposit, along with the more common fluorbritholite-(Ce), formed by a magmatic-hydrothermal fluid with REE, Si, F and Cl ion complexes reacting with dolomite marble. The presence of ulfanderssonite-(Ce) is direct evidence of a Cl-rich mineral-forming aqueous solution, normally not reflected in the composition of skarn minerals in Bastnäs-type deposits.</p>
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8.
  • Karlsson, Andreas, 1986-, et al. (författare)
  • Adding complexity to the garnet supergroup: monteneveite, Ca<sub>3</sub>Sb<sup>5+</sup><sub>2</sub>(Fe<sup>3+</sup><sub>2</sub>Fe<sup>2+</sup>)O<sub>12</sub>, a new mineral from the Monteneve mine, Bolzano Province, Italy
  • 2020
  • Ingår i: European journal of mineralogy. - 0935-1221 .- 1617-4011. ; 32:1, s. 77-87
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Monteneveite, ideally Ca<sub>3</sub>Sb<sup>5+</sup><sub>2</sub>(Fe<sup>3+</sup><sub>2</sub>Fe<sup>2+</sup>)O<sub>12</sub>, is a new member of the garnet supergroup (IMA2018-060). The mineral was discovered in a small specimen belonging to the Swedish Museum of Natural History coming from the now abandoned Monteneve Pb–Zn mine in Passiria Valley, Bolzano Province, Alto Adige (South Tyrol), Italy. The specimen consists of mainly magnetite, sphalerite, tetrahedrite-(Fe) and oxycalcioroméite. Monteneveite occurs as black, subhedral crystals with adamantine lustre. They are equidimensionaland up to 400 μm in size, with a subconchoidal fracture. Monteneveite is opaque, grey in reflected light,and isotropic under crossed polars. Measured reflectance values (%) at the four COM wavelengths are 12.6 (470 nm), 12.0 (546 nm), 11.6 (589 nm) and 11.4 (650 nm). The Vickers hardness (VHN<sub>100</sub>) is 1141 kg mm<sup>-2</sup>, corresponding to <em>H</em> = 6.5–7, and the calculated density is 4.72(1) g cm<sup>-3</sup>. A mean of 10 electron microprobe analyses gave (wt %) CaO 23.67, FeO 3.75, Fe<sub>2</sub>O<sub>3</sub> 29.54, Sb<sub>2</sub>O<sub>5</sub> 39.81, SnO<sub>2</sub> 2.22, ZnO 2.29, MgO 0.15, MnO 0.03 and CoO 0.03. The crystal chemical formula calculated on the basis of a total of eight cations and 12 anions, and taking into account the available structural and spectroscopic data, is (Ca<sub>2.97</sub>Mg<sub>0.03</sub>)<sub>Σ=3.00</sub>(Sb<sup>5+</sup><sub>1.73</sub>Sn<sup>4+</sup><sub>0.10</sub>Fe<sup>3+</sup><sub>0.17</sub>)<sub>Σ=2.00</sub>(Fe<sup>3+</sup><sub>2:43</sub>Fe<sup>2+</sup><sub>0.37</sub>Zn<sub>0.20</sub>)<sub>Σ=3.00</sub>O<sub>12</sub>. The most significant chemical variations encounteredin the sample are related to a substitution of the type <sup>Y</sup>Sn<sup>4+</sup> +<sup> Z</sup>Fe<sup>3+ </sup><img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Crightarrow" /> <sup>Y</sup>Sb<sup>5+</sup> + <sup>Z</sup>Fe<sup>2+</sup>. Mössbauer data obtained at RT and 77K indicate the presence of tetrahedrally coordinated Fe<sup>2+</sup>. Raman spectroscopy demonstrates that there is no measurable hydrogarnet component in monteneveite. The six strongest Bragg peaks in the powder X-ray diffraction pattern are [d (Å), I (%), (hkl)]: 4.45, 100, (220); 3.147, 60, (400); 2.814, 40, (420); 2.571, 80, (422); 1.993, 40, (620); 1.683, 60, (642). Monteneveite is cubic, space group Ia-3d, with a =12.6093(2) Å, V = 2004.8(1)Å<sup>3</sup>, and Z = 8. The crystal structure was refined up to R1 = 0.0197 for 305 reflections with F<sub>o</sub> &gt; 4σ (F<sub>o</sub>) and 19 parameters. Monteneveite is related to the other Ca-, Sb- and Fe-bearing, nominally Si-free members of the bitikleite group, but it differs in that it is the only known garnet species with mixed trivalent and divalent cations (2:1) at the tetrahedral Z site. Textural and mineralogical evidence suggests that monteneveite formed during peak metamorphism (at ca. 600 ºC) during partial breakdown of tetrahedrite-(Fe) by reactions with carbonate, under relatively oxidizingconditions. The mineral is named after the type locality, the Monteneve (Schneeberg) mine.</p>
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