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  • Articles  (13)
  • Springer  (7)
  • Mineralogical Society of Great Britain and Ireland  (5)
  • MDPI Publishing  (1)
  • Public Library of Science (PLoS)
  • Geosciences  (13)
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  • Articles  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Thorium and uranium isotopes in a manganese nodule from the Peru basin determined by alpha spectrometry and thermal ionization mass spectrometry (TIMS): Are manganese supply and growth related to climate? (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 577-585 
    Details
    ISSN: 1437-3262
    Keywords: Manganese nodules ; Thorium dating ; Uranium isotopes ; Peru basin ; TIMS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Thorium- and uranium isotopes were measured in a diagenetic manganese nodule from the Peru basin applying alpha- and thermal ionization mass spectrometry (TIMS). Alpha-counting of 62 samples was carried out with a depth resolution of 0.4 mm to gain a high-resolution230Thexcess profile. In addition, 17 samples were measured with TIMS to obtain precise isotope concentrations and isotope ratios. We got values of 0.06–0.59 ppb (230Th), 0.43–1.40 ppm (232Th), 0.09–0.49 ppb (234U) and 1.66–8.24 ppm (238U). The uranium activity ratio in the uppermost samples (1–6 mm) and in two further sections in the nodule at 12.5±1.0 mm and 27.3–33.5 mm comes close to the present ocean water value of 1.144±0.004. In two other sections of the nodule, this ratio is significantly higher, probably reflecting incorporation of diagenetic uranium. The upper 25 mm section of the Mn nodule shows a relatively smooth exponential decrease in the230Thexcess concentration (TIMS). The slope of the best fit yields a growth rate of 110 mm/Ma up to 24.5 mm depth. The section from 25 to 30.3 mm depth shows constant230Thexcess concentrations probably due to growth rates even faster than those in the top section of the nodule. From 33 to 50 mm depth, the growth rate is approximately 60 mm/Ma. Two layers in the nodule with distinct laminations (11–15 and 28–33 mm depth) probably formed during the transition from isotopic stage 8 to 7 and in stage 5e, respectively. The Mn/Fe ratio shows higher values during interglacials 5 and 7, and lower ones during glacials 4 and 6. A comparison of our data with data from adjacent sediment cores suggests (a) a variable supply of hydrothermal Mn to sediments and Mn nodules of the Peru basin or (b) suboxic conditions at the water sediment interface during periods with lower Mn/Fe ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02369012
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Thorium and uranium isotopes in a manganese nodule from the Peru basin determined by alpha spectrometry and thermal ionization mass spectrometry (TIMS): Are manganese supply and growth related to climate? (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 577-585 
    Details
    ISSN: 0016-7835
    Keywords: Key words Manganese nodules ; Thorium dating ; Uranium isotopes ; Peru basin ; TIMS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Thorium- and uranium isotopes were measured in a diagenetic manganese nodule from the Peru basin applying alpha- and thermal ionization mass spectrometry (TIMS). Alpha-counting of 62 samples was carried out with a depth resolution of 0.4 mm to gain a high-resolution 230Thexcess profile. In addition, 17 samples were measured with TIMS to obtain precise isotope concentrations and isotope ratios. We got values of 0.06–0.59 ppb (230Th), 0.43-1.40 ppm (232Th), 0.09–0.49 ppb (234U) and 1.66–8.24 ppm (238U). The uranium activity ratio in the uppermost samples (1–6 mm) and in two further sections in the nodule at 12.5±1.0 mm and 27.3–33.5 mm comes close to the present ocean water value of 1.144±0.004. In two other sections of the nodule, this ratio is significantly higher, probably reflecting incorporation of diagenetic uranium. The upper 25 mm section of the Mn nodule shows a relatively smooth exponential decrease in the 230Thexcess concentration (TIMS). The slope of the best fit yields a growth rate of 110 mm/Ma up to 24.5 mm depth. The section from 25 to 30.3 mm depth shows constant 230Thexcess concentrations probably due to growth rates even faster than those in the top section of the nodule. From 33 to 50 mm depth, the growth rate is approximately 60 mm/Ma. Two layers in the nodule with distinct laminations (11–15 and 28–33 mm depth) probably formed during the transition from isotopic stage 8 to 7 and in stage 5e, respectively. The Mn/Fe ratio shows higher values during interglacials 5 and 7, and lower ones during glacials 4 and 6. A comparison of our data with data from adjacent sediment cores suggests (a) a variable supply of hydrothermal Mn to sediments and Mn nodules of the Peru basin or (b) suboxic conditions at the water sediment interface during periods with lower Mn/Fe ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050098
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  • 3
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    Agmantinite, Ag2MnSnS4, a new mineral with a wurtzite derivative structure from the Uchucchacua polymetallic deposit, Lima Department, Peru (2018)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉 〈p〉Agmantinite, ideally Ag〈span〉2〈/span〉MnSnS〈span〉4〈/span〉, is a new mineral from the Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru. It occurs as orange–red crystals up to 100 μm across. Agmantinite is translucent with adamantine lustre and possesses a red streak. It is brittle. Neither fracture nor cleavage were observed. Based on the empirical formula the calculated density is 4.574 g/cm〈span〉3〈/span〉. On the basis of chemically similar compounds the Mohs hardness is estimated at between 2 to 2½. In plane-polarised light agmantinite is white with red internal reflections. It is weakly bireflectant with no observable pleochroism with red internal reflections. Between crossed polars, agmantinite is weakly anisotropic with reddish brown to greenish grey rotation tints. The reflectances (〈span〉R〈/span〉〈span〉min〈/span〉 and 〈span〉R〈/span〉〈span〉max〈/span〉) for the four standard wavelengths are: 19.7 and 22.0 (470 nm); 20.5 and 23.2 (546 nm); 21.7 and 2.49 (589 nm); and 20.6 and 23.6 (650 nm), respectively.〈/p〉 〈p〉Agmantinite is orthorhombic, space group 〈span〉P〈/span〉2〈span〉1〈/span〉〈span〉nm〈/span〉, with unit-cell parameters: 〈span〉a〈/span〉 = 6.632(2), 〈span〉b〈/span〉 = 6.922(2), 〈span〉c〈/span〉 = 8.156(2) Å, 〈span〉V〈/span〉 = 374.41(17) Å〈span〉3〈/span〉, 〈span〉a〈/span〉:〈span〉b〈/span〉:〈span〉c〈/span〉 0.958:1:1.178 and 〈span〉Z〈/span〉 = 2. The crystal structure was refined to 〈span〉R〈/span〉 = 0.0575 for 519 reflections with 〈span〉I 〉〈/span〉 2σ(〈span〉I〈/span〉). Agmantinite is the first known mineral of 〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20190522072108342-0385:S0026461X18001391:S0026461X18001391_inline1.gif"〉 〈span data-mathjax-type="texmath"〉 〈/span〉 〈/span〉〈/span〉〈span〉M〈/span〉〈span〉II〈/span〉〈span〉M〈/span〉〈span〉IV〈/span〉S〈span〉4〈/span〉 type that is derived from wurtzite rather than sphalerite by ordered substitution of Zn, analogous to the substitution pattern for deriving stannite from sphalerite. The six strongest X-ray powder-diffraction lines derived from single-crystal X-ray diffraction data [〈span〉d〈/span〉 in Å (intensity)] are: 3.51 (s), 3.32 (w), 3.11 (vs), 2.42 (w), 2.04 (m) and 1.88 (m). The empirical formula (based on 8 apfu) is (Ag〈span〉1.94〈/span〉Cu〈span〉0.03〈/span〉)〈span〉Σ1.97〈/span〉(Mn〈span〉0.98〈/span〉Zn〈span〉0.05〈/span〉)〈span〉Σ1.03〈/span〉Sn〈span〉0.97〈/span〉S〈span〉4.03〈/span〉.The crystal structure-derived formula is Ag〈span〉2〈/span〉(Mn〈span〉0.69〈/span〉Zn〈span〉0.31〈/span〉)〈span〉Σ1.00〈/span〉SnS〈span〉4〈/span〉 and the simplified formula is Ag〈span〉2〈/span〉MnSnS〈span〉4〈/span〉.〈/p〉 〈p〉The name is for the composition and the new mineral and mineral name have been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2014-083).〈/p〉 〈/div〉
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 4
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    Structural and chemical study of weishanite, (Au,Ag,Hg), from the Keystone mine, Colorado, USA. (2018)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉〈p〉Structural data for weishanite, an alloy of Au, Ag and Hg, were collected for the first time from a crystal from the Keystone Mine, Colorado, USA. The structure was solved in the space group 〈span〉P〈/span〉6〈span〉3〈/span〉/〈span〉mmc〈/span〉 with the unit cell 〈span〉a〈/span〉 = 2.9348(8) and 〈span〉c〈/span〉 = 4.8215(18) Å] and refined to 〈span〉R〈/span〉 = 0.0299 for 40 observed reflections [4σ(〈span〉F〈/span〉) level] and four parameters and to 〈span〉R〈/span〉 = 0.0356 for all 47 independent reflections. The weishanite structure can be considered a derivative of the zinc structure, with Au, Ag and Hg disordered in the same structural position. On this basis, we suggest that the formula is normalized to 1 atom with 〈span〉Z〈/span〉 = 2, leading, for the sample investigated, to Au〈span〉0.41〈/span〉Ag〈span〉0.31〈/span〉Hg〈span〉0.28〈/span〉 (electron microprobe data). Accordingly, weishanite can be considered the Au-rich isotype of schachnerite. A comparison with other Au/Ag-Hg alloys is presented together with a critical discussion about the nomenclature rules to be applied to alloys and simple metals.〈/p〉〈/div〉
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 5
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    Minerals, Vol. 8, Pages 192: Oyonite, Ag3Mn2Pb4Sb7As4S24, a New Member of the Lillianite Homologous Series from the Uchucchacua Base-Metal Deposit, Oyon District, Peru (2018)
    MDPI Publishing
    In: Minerals
    Details
    Publication Date: 2018-05-03
    Description: Minerals, Vol. 8, Pages 192: Oyonite, Ag3Mn2Pb4Sb7As4S24, a New Member of the Lillianite Homologous Series from the Uchucchacua Base-Metal Deposit, Oyon District, Peru Minerals doi: 10.3390/min8050192 Authors: Luca Bindi Cristian Biagioni Frank N. Keutsch The new mineral species oyonite, ideally Ag3Mn2Pb4Sb7As4S24, has been discovered in the Uchucchacua base-metal deposit, Oyon district, Catajambo, Lima Department, Peru, as very rare black metallic subhedral to anhedral crystals, up to 100 μm in length, associated with orpiment, tennantite/tetrahedrite, menchettiite, and other unnamed minerals of the system Pb-Ag-Sb-Mn-As-S, in calcite matrix. Its Vickers hardness (VHN100) is 137 kg/mm2 (range 132–147). In reflected light, oyonite is weakly to moderately bireflectant and weakly pleochroic from dark grey to a dark green. Internal reflections are absent. Reflectance values for the four COM wavelengths [Rmin, Rmax (%) (λ in nm)] are: 33.9, 40.2 (471.1); 32.5, 38.9 (548.3), 31.6, 38.0 (586.6); and 29.8, 36.5 (652.3). Electron microprobe analysis gave (in wt %, average of 5 spot analyses): Cu 0.76 (2), Ag 8.39 (10), Mn 3.02 (7), Pb 24.70 (25), As 9.54 (12), Sb 28.87 (21), S 24.30 (18), total 99.58 (23). Based on 20 cations per formula unit, the chemical formula of oyonite is Cu0.38Ag2.48Mn1.75Pb3.79Sb7.55As4.05S24.12. The main diffraction lines are (d in Å, hkl and relative intensity): 3.34 (−312; 40), 3.29 (−520; 100), 2.920 (−132; 40), 2.821 (−232; 70), 2.045 (004; 50). The crystal structure study revealed oyonite to be monoclinic, space group P21/n, with unit-cell parameters a = 19.1806 (18), b = 12.7755 (14), c = 8.1789 (10) Å, β = 90.471 (11)°, V = 2004.1 (4) Å3, Z = 2. The crystal structure was refined to a final R1 = 0.032 for 6272 independent reflections. Oyonite belongs to the Sb-rich members of the andorite homeotypic sub-series within the lillianite homologous series. The name oyonite is after the Oyon district, Lima Department, Peru, the district where the type locality (Uchucchacua mine) is located.
    Electronic ISSN: 2075-163X
    Topics: Geosciences
    Published by MDPI Publishing
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  • 6
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    Structural and chemical study of weishanite, (Au,Ag,Hg), from the Keystone mine, Colorado, USA. (2018)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2018-05-29
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 7
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    Polloneite, a new complex Pb(-Ag)-As-Sb sulfosalt from the Pollone mine, Apuan Alps, Tuscany, Italy (2017)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2017-12-01
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 8
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    Solenosmilia variabilis-bearing cold-water coral mounds off Brazil (2019)
    Springer
    Details
    Publication Date: 2019-12-11
    Print ISSN: 0722-4028
    Electronic ISSN: 1432-0975
    Topics: Biology , Geosciences
    Published by Springer
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  • 9
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    Agmantinite, Ag2MnSnS4, a new mineral with a wurtzite derivative structure from the Uchucchacua polymetallic deposit, Lima Department, Peru (2018)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2018-07-02
    Description: Agmantinite, ideally Ag2MnSnS4, is a new mineral from the Uchucchacua polymetallic deposit, Oyon district, Catajambo, Lima Department, Peru. It occurs as orange–red crystals up to 100 μm across. Agmantinite is translucent with adamantine lustre and possesses a red streak. It is brittle. Neither fracture nor cleavage were observed. Based on the empirical formula the calculated density is 4.574 g/cm3. On the basis of chemically similar compounds the Mohs hardness is estimated at between 2 to 2½. In plane-polarised light agmantinite is white with red internal reflections. It is weakly bireflectant with no observable pleochroism with red internal reflections. Between crossed polars, agmantinite is weakly anisotropic with reddish brown to greenish grey rotation tints. The reflectances (Rmin and Rmax) for the four standard wavelengths are: 19.7 and 22.0 (470 nm); 20.5 and 23.2 (546 nm); 21.7 and 2.49 (589 nm); and 20.6 and 23.6 (650 nm), respectively.Agmantinite is orthorhombic, space group P21nm, with unit-cell parameters: a = 6.632(2), b = 6.922(2), c = 8.156(2) Å, V = 374.41(17) Å3, a:b:c 0.958:1:1.178 and Z = 2. The crystal structure was refined to R = 0.0575 for 519 reflections with I > 2σ(I). Agmantinite is the first known mineral of ${M}_{ m 2}^{ m I} $MIIMIVS4 type that is derived from wurtzite rather than sphalerite by ordered substitution of Zn, analogous to the substitution pattern for deriving stannite from sphalerite. The six strongest X-ray powder-diffraction lines derived from single-crystal X-ray diffraction data [d in Å (intensity)] are: 3.51 (s), 3.32 (w), 3.11 (vs), 2.42 (w), 2.04 (m) and 1.88 (m). The empirical formula (based on 8 apfu) is (Ag1.94Cu0.03)Σ1.97(Mn0.98Zn0.05)Σ1.03Sn0.97S4.03.The crystal structure-derived formula is Ag2(Mn0.69Zn0.31)Σ1.00SnS4 and the simplified formula is Ag2MnSnS4.The name is for the composition and the new mineral and mineral name have been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2014-083).
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
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  • 10
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    Thorium and uranium isotopes in a manganese nodule from the Peru basin determined by alpha spectrometry and thermal ionization mass spectrometry (TIMS): Are manganese supply and growth related to climate? (1996)
    Springer
    Details
    Publication Date: 1996-09-01
    Print ISSN: 0016-7835
    Electronic ISSN: 1432-1149
    Topics: Geosciences
    Published by Springer
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