A Mössbauer effect study of Fe environments in impact glasses

Dunlap, R. A.; McGraw, Joshua D.

doi:10.1016/j.jnoncrysol.2007.03.006

Cited by 9 publications

(7 citation statements)

References 15 publications

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“…The two doublets resolved in the spectra provide information on probable local coordination of iron in the moldavite samples. Subordinate distribution may be interpreted unambiguously, in agreement with Dunlap (1997), Dunlap et al (1998), Rossano et al (1999a,b), Dunlap and Sibley (2004), and Dunlap and McGraw (2007) as a minor amount of tetrahedrally coordinated ferrous iron. However, the assignment of the coordination number to the second, dominant, distribution is equivocal.…”

Section: Ferrous-to-ferric Iron Ratios and Iron Coordinationsupporting

confidence: 82%

“…18), and resemble those collected from other tektites (Dunlap, 1997;Dunlap et al, 1998;Rossano et al, 1999a;Dunlap and Sibley, 2004), impact glasses (Dunlap and McGraw, 2007), and reduced silicate glass (see, for example, Alberto et al, 1996;McCammon, 2004). An obvious shoulder may be noted between the two main components, which indicate the presence of at least two components.…”

Section: Ferrous-to-ferric Iron Ratios and Iron Coordinationmentioning

confidence: 51%

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Moldavites from the Cheb Basin, Czech Republic

Skála

Strnad

McCammon

et al. 2009

Geochimica et Cosmochimica Acta

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Section: Ferrous-to-ferric Iron Ratios and Iron Coordinationsupporting

confidence: 82%

Section: Ferrous-to-ferric Iron Ratios and Iron Coordinationmentioning

confidence: 51%

Moldavites from the Cheb Basin, Czech Republic

Skála

Strnad

McCammon

et al. 2009

Geochimica et Cosmochimica Acta

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“…Bin used is 5 × 10 −9 m 3 /kg. Magnetic mineralogy of these impact glasses is dominated by substituted magnetite [9,[10][11][12]51], as expected by their generally oxidized nature indicated for example by XANES (for LDG, Aouelloul, irghizite, Wabar; [27,45]) or Mössbauer spectroscopy studies (for Aouelloul, irghizite, Wabar; [44]). Substitution in magnetite is revealed by the spread of Curie or remanence unblocking temperatures well below 580 °C, as well as the lack or subdued character of the Verwey transition [10,12,53].…”

Section: Glasssupporting

confidence: 55%

“…The Fe K-edge Masaitis et al [42] reported Mössbauer spectroscopy (MS) data compatible with the lack of Fe 3+ . As MS data may be ambiguous to allow discussion of the oxidation state of iron [44], we undertook X-ray spectroscopic investigations at the Fe edge of U1 sample (the richest in iron). The Fe K-edge XANES spectrum of the urengoite sample is shown in Figure 8, whereas the background subtracted pre-edge peak (labeled P in the XANES spectrum) is shown in the inset.…”

Section: Urengoitesmentioning

confidence: 99%

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

et al. 2019

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High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.

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“…Additionally, for the Muong Nong tektites we have obtained higher Fe 3+ /Fe 2+ ratios than for other tektites. Impactites, including Darwin Glasses, have lower contents of Fe 2+ octahedral component than tektites [60]. We have accordingly obtained 75% of Fe 2+ in octahedral coordination against 80-90% in tektites, but with similar hyperfine parameters.…”

Section: Tektitesmentioning

confidence: 60%

57Fe Mössbauer Analysis of Meteorites and Tektites

et al. 2021

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This review presents studies on iron meteorites (Campo del Cielo fall and an unregistered iron meteorite), an unregistered stony meteorite from Northwest Africa, and 13 tektites from the American, European, and Australasian strewn fields. The main experimental technique used in the studies was Mössbauer spectroscopy, both in transmission and backscattering geometries. For the latter, a MIMOS II spectrometer was used. Additionally, optical and scanning electron microscopies and X-ray diffraction were used. In the studied iron meteorites, kamacite is found as the main mineral. Campo del Cielo meteorite exhibits Widmanstätten patterns and schreibersite inclusions. The unregistered iron meteorite has Neumann lines and schreibersite inclusions. We have assigned Campo del Cielo as an octahedrite and the unregistered iron meteorite as a hexahedrite. The unregistered stony meteorite is composed mainly of iron-free silicates; at 4.2 K, the spectrum indicates maghemite and 1% troilite. The Cambodian tektite appeared individualized from other australasites, unlike the moldavite, which tends to cluster with them. Our analyses do not allow dismissing doubts on the provenance of tibetanites. The Fe3+/Fe2+ ratio was found to be higher for Muong Nong-type tektites than for splash-form tektites, as expected from their morphology and solidification from melt at lower temperature.

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A Mössbauer effect study of Fe environments in impact glasses

Cited by 9 publications

References 15 publications

Moldavites from the Cheb Basin, Czech Republic

Moldavites from the Cheb Basin, Czech Republic

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

57Fe Mössbauer Analysis of Meteorites and Tektites

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