Mössbauer Spectra of Glauconites Reexamined

Rozenson, I.; Heller-Kallai, L.

doi:10.1346/ccmn.1978.0260214

Cited by 26 publications

(15 citation statements)

References 6 publications

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“…To test this possibility, the analyses were repeated with the absorber held at 80 + I~ At this lower temperature the absorption shoulder disappeared, and the peaks showed a more symmetrical configuration (see Figure 3) as previously noted by Rolf et al (1977). The exceptionally high line widths of 1.37 mm/sec (noted by Rozenson and Heller-Kallai, 1978) for some Fe ~+ doublets also disappeared at low temperature, because they represent the absorption shoulder and not a true absorption peak. The difference in spectral form which resulted from the change in absorber temperature is very marked and may explain the observation that while a good fit can be obtained for deblackened data recorded at the lower temperature, the same is not true for data recorded at room temperature.…”

Section: Effect Of Absorber Temperature On Peak Resolutionmentioning

confidence: 71%

“…Each unit cell of a phyllosilicate mineral has three possible octahedral sites: one M(1) site with hydroxyl groups arranged in a trans configuration, and two M(2) sites with the hydroxyl groups arranged in a cis configuration (Rolf et al, 1977;Rozenson and Heller-Kallai, 1978). In an ideal structure the two M(2) sites are equivalent, while the M(1) site is slightly larger (Rozenson and Heller-Kallai, 1977).…”

Section: Interpretation Of the Mrssbauer Spectramentioning

confidence: 99%

“…This paper amplifies earlier studies by M/Sssbauer analysis of the sedimentary mineral glauconite (cf. Rolf et al, 1977;Rozenson and Heller-Kallai, 1978).…”

Section: Introductionmentioning

confidence: 99%

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A Mössbauer Investigation of Glauconite and its Geological Significance

McConchie

1979

Clays and clay miner.

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Ahstraet--M6ssbauer spectra of 9 glauconite samples from Upper Cretaceous and Lower Tertiary strata in the South Island of New Zealand contain a broad shoulder due to low intensity absorption continuous between 1.0 and 2.5 mm/sec when the absorber is at room temperature; the shoulder is absent, and sharp peaks are apparent in spectra taken with the absorber at 80~ The data suggest that electron transfer occurs between adjacent Fe 3+ and Fe z+ ions at room temperature. The low temperature spectra indicate that all Fe in the glauconites is in octahedral coordination. Fe z+ and Fe z+ ions occur in both cis and trans sites; Fe z+ shows a strong preference for cis sites whereas Fe 2+ shows an even stronger preference for trans sites.The partially variable oxidation state of Fe in glauconite is interpreted in terms of a geochemical model for glauconitization of a degraded or incomplete progenitor phyllosilicate. The model involves exchange of Fe ~+ for other cations which temporarily stabilize the progenitor, followed by FeZ § 3+ charge transfer reactions. Each reaction results from the system's tendency towards equilibrium. The model is supported by the observation that artificially leached glauconite increases both its Fe z+ and its Fe z+ content when placed in a solution containing Fe 2+ as the only Fe ion present.

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Section: Effect Of Absorber Temperature On Peak Resolutionmentioning

confidence: 71%

Section: Interpretation Of the Mrssbauer Spectramentioning

confidence: 99%

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A Mössbauer Investigation of Glauconite and its Geological Significance

McConchie

1979

Clays and clay miner.

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“…In other minerals intermediate states were observed. Comparison of the distribution of iron in nontronite with that in glauconite, in which iron shows strong preference for M(2) sites (Rozenson and Heller-Kallai, 1978) proves that the site occupancy is not dictated by the amount of iron present.…”

Section: Discussionmentioning

confidence: 95%

Order-Disorder Phenomena Accompanying the Dehydroxylation of Dioctahedral Phyllosilicates

Rozenson

Heller-Kallai

1980

Clays and clay miner.

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“…Until recently, the widely accepted interpretation of M6ssbauer spectra of Fe3+-rich dioctahedral 2:1 layer silicates consisted of decomposition of the corresponding spectrum into two main doublets which were assumed to be related to Fe 3+ ions in cis-and trans-octahedra of 2:1 layers (Heller-Kallai & Rozenson, 1981;Rozenson & Heller-Kallai, 1978;Govaert et al, 1978;Kotlicki et al, 1981;De Grave et al, 1985;Johnston & Cardile, 1987;Cardile & Brown, 1988). As was mentioned, the XRD data showed that trans-sites are vacant in most Fe3+-rich dioctahedral 2:1 layer silicates.…”

Section: Mossbauer Spectroscopymentioning

confidence: 99%

Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies

et al. 1997

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AB S TRACT: Celadonite, glauconite and Fe-illite samples were studied by XRD, EXAFS, IR and M6ssbauer spectroscopy. The samples were monomineralic and corresponded to IM polytype. In the OH-stretching region of the IR spectra the content of each definite pair of cations bonded to OH groups was determined. The number of heavy (Fe) and light (AI, Mg) octahedral cations nearest to Fe was found by the EXAFS technique. The predicted quadrupole splitting values for each definite arrangement of cations nearest to Fe 3+ were used to interpret the M6ssbauer spectra. After the fitting procedure, the intensity of each doublet corresponded to a definite set of local cation arrangements around Fe 3+ and to a definite occurrence probability of these arrangements. Computer simulation and the experimental data obtained were used to reconstruct the distribution of isomorphous octahedral cations in the 2:1 layers. For all samples, R 2+ cations prefer to occupy one of the two symmetrically independent cis-sites and RZ+-R 2+ and/or AI-Fe 3+ were prohibited in the directions forming _+ 120 ~ with the b axis. Therefore, octahedral sheets of the samples revealed domain structure, in which domains differ in size, in the nature of predominant cation and/or by cation ordering.One of the characteristic features of phyllosilicates and, in particular, dioctahedral micas, is a wide variation of chemical compositions. Different samples of the same mineral may differ not only in octahedral and tetrahedral cation contents of 2:1 layers, but also in their long-and short-range ordering in isomorphous cation distribution. Determination of the actual cation distribution in dioctahedral micas is a complex problem. X-ray diffraction (XRD) yields data only on the averaged composition of cations in the unit-cell sites, ignoring a possible short-range ordering. For finely dispersed minerals containing stacking faults, even this information is often difficult to obtain.Spectroscopic methods are, therefore, especially useful, since they probe local atomic environments and have a potential to determine short-range cation ordering. Utilization of spectroscopic methods, however, often meets certain difficulties. One of the main problems is that most of these methods are indirect, that is, they provide indirect structural information about a sample under study. For this reason, interpretation of spectroscopic data is not always feasible or properly based.One of the effective ways to determine the actual cation distribution consists of the application of complex diffraction and spectroscopic methods to the same sample. Obviously, the greater the number of methods involved, the more comprehensive the structural information obtained. Each method, however, has its own advantages and limitations and therefore provides only a partial solution to a 9 1997 The Mineralogical Society 154 K A. Drits et al.general problem of cation order/disorder in dioctahedral mica structures. Therefore, even if unambiguous interpretation of experimental data is provided, the actual ca...

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Mössbauer Spectra of Glauconites Reexamined

Cited by 26 publications

References 6 publications

A Mössbauer Investigation of Glauconite and its Geological Significance

A Mössbauer Investigation of Glauconite and its Geological Significance

Order-Disorder Phenomena Accompanying the Dehydroxylation of Dioctahedral Phyllosilicates

Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies

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