ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1990-1994  (34)
  • 1985-1989  (12)
  • 1975-1979  (19)
  • 1
    Monograph available for loan
    Monograph available for loan
    Cambridge : Cambridge Univ. Pr.
    Associated volumes
    Call number: M 95.0470 ; 11/M 93.0961
    In: Cambridge topics in mineral physics and chemistry
    Type of Medium: Monograph available for loan
    Pages: XXIII, 551 S. : graph. Darst.
    Edition: 2nd ed.
    ISBN: 0521430771
    Series Statement: Cambridge topics in mineral physics and chemistry 5
    Classification:
    Mineralogy
    Language: English
    Location: Upper compact magazine
    Location: Reading room
    Branch Library: GFZ Library
    Branch Library: GFZ Library
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 320 (1986), S. 55-56 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The red colour of the surface of Mars has long been attributed to Fe3+-bearing minerals in the regolith, implying that oxidizing conditions have prevailed. However, the apparent enrichment of iron in martian regolith, its mineralogy and the nature of the unweathered parent rocks remain poorly ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 51 (1975), S. 213-221 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Olivine inclusions in diamonds from kimberlites originating from the deep Upper Mantle contain significant amounts of chromium. It has been suggested that divalent chromium occurs in these olivines. This hypothesis is supported by recent Mössbauer and electronic spectral measurements at high pressures, which demonstrate that pressure-induced reduction takes place in compounds and minerals initially containing Fe3+, Mn3+, and Cu2+ ions. The process is facilitated at high temperatures. Low oxidation states of other metals such as Cr(II) are expected to be stabilized under the very high pressures and elevated temperature conditions in the Mantle. Since Cr2+ ions are susceptible to the Jahn-Teller effect, they are predicted by crystal field theory to be stabilized in certain distorted coordination sites, such as the olivine Ml site, all three sites of the β-spinel phase, and the 7-coordinated site of the strontium plumbate structure-type. The Cr2+ ions in olivines are stabilized in kimberlites intruded into the Crust by the high confining pressures in the diamond inclusions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 255 (1975), S. 130-131 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Observations of the interiors of manganese nodules under the microscope5, together with electron microprobe analyses6"8, reveal the intimate associations and oscillatory intergrowths of the manganese- and iron-bearing minerals. Most nodules have formed about a nucleus consisting of pumice, altered ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 253 (1975), S. 614-616 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] One type of manganese mineralisation is related to calc-alkaline magmatism. Reports on porphyry copper deposits and numerous manganese ore deposits have revealed that the two mineralisations seem to be contemporaneous within calc-alkaline terrains11. Porphyry copper deposits consistently occur over ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 2 (1978), S. 177-197 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Comparisons of structural features of olivine (α phase), spinel (γ phase), and the modified spinel (β phase) lead to predictions of possible mechanisms for the olivine → spinel transitions. In the olivine structure, rigid tetrahedral edges and shared octahedral edges form columns of corner-sharing trigonal dipyramids parallel to the a axis. These rigid columns are separated by weaker, unshared octahedral edges which may be stretched to reduce cation-cation repulsion. As a result, olivine has a relatively loose structure and is stable at low pressure. At elevated pressure, olivine transforms to the more compact spinel structure, in which the rigid tetrahedral edges and shared octahedral edges form a three dimensional network instead of aligned columns. These structural differences explain how compressibility and thermal expansion may be taken up mainly by octahedral sites in olivine, but are evenly distributed over both octahedral and tetrahedral sites in spinel. Because the closest packings of oxygens and interstitial cation distributions differ between olivine (h.c.p.) and spinel (c.c.p.), the olivine structure may have to disintegrate during its transformation to spinel, so that the olivine → spinel transition involves processes of nucleation and growth. The migration of atoms across the olivine-spinel interface is thus a complicated process of random walk without a definite path. In the β phase → spinel transition, however, the diffusion of cations may follow a definite path in restricted regions because oxygen closest packings and cation distributions are similar in the two structures. If the oxygen packing remains intact during the β → γ transition, the transformation will be an intracrystalline process leading to domain structure in the spinel product.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 1 (1977), S. 301-311 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The blue colors of several minerals and gems, including aquamarine (beryl, Be3Al2Si6O18) and cordierite (Al3(Mg, Fe)2Si5AlO18), have been attributed to charge transfer (CT) between adjacent Fe2+ and Fe3+ cations, while Fe2+→Ti4+ CT has been proposed for blue kyanites (Al2SiO5). Such assignments were based on chemical analyses and on polarization-dependent absorption bands measured in visible-region spectra. We have attempted to characterize the Fe cations in each of these minerals by Mössbauer spectroscopy (MS). In blue kyanites, significant amounts of both Fe2+ and Fe3+ were detected with MS, indicating that Fe2+→Fe3+ CT, Fe2+→Ti4+ CT, and Fe2+ and Fe3+ crystal field transitions each could contribute to the electronic spectra. In aquamarines, coexisting Fe2+ and Fe3+ ions were resolved by MS, supporting our assignment of the broad, relatively weak band at 16,100 cm−1 in E∥c spectra to Fe2+→Fe3+ CT between Fe cations replacing Al3+ ions 4.6Å apart along c. A band at 17,500 cm−1 in E⊥c spectra of cordierite is generally assigned to Fe2+ (oct)→Fe3+ (tet) CT between cations only 2.74 Å apart. However, no Fe3+ ions were detected in the MS at 293K of several blue cordierites showing the 17,500 cm−1 band and reported to contain Fe3+. A quadrupole doublet with parameters consistent with tetrahedral Fe3+ appears in 77K MS, but the Fe3+/Fe2+ ratios from MS are much smaller than values from chemical analysis. These results sound a cautionary note when correlating Mössbauer and chemically determined Fe3+/Fe2+ ratios for minerals exhibiting Fe2+→Fe3+ CT.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 2 (1978), S. 349-364 
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Crystal field stabilization (CFS) plays a significant role in determining equilibrium phase boundaries in olivine→spinel transformations involving transition-metal cations, including Fe2+ which is a major constituent of the upper mantle. Previous calculations for Fe2SiO4 ignored pressure and temperature dependencies of crystal field stabilization enthalpies (CFSE) and the electronic configurational entropy (S CFS). We have calculated free energy changes (ΔG CFS) due to differences of crystal field splittings between Fe2SiO4 spinel and fayalite from: ΔG CFS=−ΔCFSE−TΔS CFS, as functions of P and T, for different energy splittings of t 2g orbital levels of Fe2+ in spinel. The results indicate that ΔG CFS is always negative, suggesting that CFS always promotes the olivine→spinel transition in Fe2SiO4, and expands the stability field of spinel at the expense of olivine. Because of crystal field effects, transition pressures for olivine→spinel transformations in compositions (Mg1−x Fe x )2SiO4 are lowered by approximately 50x kbar, which is equivalent to having raised the olivine→spinel boundary in the upper mantle by about 15 km.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 91 (1994), S. 571-576 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Determination of oxidation states and the crystal chemistry of iron-bearing minerals in carbonaceous chondrites by Mössbauer spectroscopy is complicated by thermally-induced electron-hopping in cronstedtite, superparamagnetism of hydrous ferric oxides and ill-defined contributions from an incommensurate layered iron sulfide phase believed to be tochilinite. Mössbauer spectra measurements at 30 K of several terrestrial cronstedtite and tochilinite specimens have enables modal proportions of these minerals, as well as Fe3+/Fe2+ ratios, to be determined quantitatively in a suite of CM-type meteorites.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 91 (1994), S. 739-745 
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The variety of coordination numbers, symmetries, distortions and ligand environments in thermally-stable iron-bearing minerals provide wide ranges of chemical shift (δ) and quadrupole splitting (δ) parameters, which serve to characterize the crystal chemistries and site occupancies of Fe2+ and Fe3+ ions in minerals of terrestrial and extraterrestrial origins. Correlations between ferrous and ferric chemical shifts enable thermally-induced electron delocalization behavior in mixed-valence Fe2+-Fe3+ minerals to be identified, while chemical shift versus quadrupole splitting correlations serve to identify nanophase ferric oxides and oxyhydroxides in oxidized minerals and in meteorites subjected to aqueous oxidation before and after they arrived on Earth.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...