Structure of Iron Silicate Glasses and Melts

Mysen, Bjørn O.; Richet, Pascal

doi:10.1016/b978-0-444-63708-6.00011-9

Cited by 93 publications

(154 citation statements)

References 79 publications

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“…Alkaline melts have relatively higher Fe 3+ /(Fe 3+ + Fe 2+ ) ratio, then non-alkaline melts [70,71], and Fe 3+ is partly included in forsterite. The rock cooling causes exsolution of Fe 3+ -rich forsterite into diopside and magnetite [72] titanomagnetite in interstices of olivine grains (Figure 3a) up to formation of magnetite-rich peridotite (see Figure 1) that have economic importance [9].…”

Section: Discussionmentioning

confidence: 99%

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

et al. 2018

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The Kovdor alkaline-ultrabasic massif (NW Russia) is formed by three consequent intrusions: peridotite, foidolite-melilitolite and phoscorite-carbonatite. Forsterite is the earliest mineral of both peridotite and phoscorite-carbonatite, and its crystallization governed evolution of magmatic systems. Crystallization of forsterite from CaFe rich peridotite melt produced Si-Al-Na-K-rich residual melt-I corresponding to foidolite-melilitolite. In turn, consolidation of foidolite and melilitolite resulted in Fe-Ca-C-P-F-rich residual melt-II that emplaced in silicate rocks as a phoscorite-carbonatite pipe. Crystallization of phoscorite began from forsterite, which launched destruction of silicate-carbonate-ferri-phosphate subnetworks of melt-II, and further precipitation of apatite and magnetite from the pipe wall to its axis with formation of carbonatite melt-III in the pipe axial zone. This petrogenetic model is based on petrography, mineral chemistry, crystal size distribution and crystallochemistry of forsterite. Marginal forsterite-rich phoscorite consists of Fe 2+-Mn-Ni-Ti-rich forsterite similar to olivine from peridotite, intermediate low-carbonate magnetite-rich phoscorite includes Mg-Fe 3+-rich forsterite, and axial carbonate-rich phoscorite and carbonatites contain Fe 2+-Mn-rich forsterite. Incorporation of trivalent iron in the octahedral M1 and M2 sites reduced volume of these polyhedra; while volume of tetrahedral set has not changed. Thus, trivalent iron incorporates into forsterite by schema (3Fe 2+) oct → (2Fe 3+ +) oct that reflects redox conditions of the rock formation resulting in good agreement between compositions of apatite, magnetite, calcite and forsterite.

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Section: Discussionmentioning

confidence: 99%

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

et al. 2018

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“…40 In the X-ray and neutron PDFs shown in Figure 4 A and B, respectively, the Si-O distance is observed at 1.62 Å, which aligns with the values reported in the literature for silicate glasses. [41][42][43][44] The Ca-O correlation is observed as a shoulder or smaller peak at approx. 2.25-2.30 Å.…”

Section: Cao-feo X -Sio 2 Slagsmentioning

confidence: 99%

Molecular structure of CaO–FeO_x–SiO₂ glassy slags and resultant inorganic polymer binders

et al. 2018

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The molecular structures of CaO–FeOx–SiO2 slags and their inorganic polymer counterparts were determined using neutron and X‐ray scattering with subsequent pair distribution function (PDF) analysis. The slags were synthesized with approximate molar compositions: 0.17CaO–0.83FeO–SiO2 and 0.33CaO–0.67FeO–SiO2 (referred to as low‐Ca and high‐Ca, respectively). The PDF data on the slags reasserted the predominantly glassy nature of this iron‐rich industrial byproduct. The dominant metal‐metal correlation was Fe–Si (3.20‐3.25 Å), with smaller contributions from Fe–Ca (3.45‐3.50 Å) and Fe–Fe (2.95‐3.00 Å). After inorganic polymer synthesis, a rise in the amount of Fe3+ was observed via the shift of the Fe–O bond length to shorter distances. This shortening of the Fe–O distance in the binder is also evidenced by the apparent rise of the Fe–Fe correlation at 2.95‐3.00 Å, although this feature may also suggest a potential aggregation of FeOx clusters. In general, the atomic arrangements of the reaction product was shown to be very similar to the precursor structure and the dominance of the Fe–Si correlation suggests the participation of Fe in the silicate network. The binder was shown to be glassy, as no distinct atom‐atom correlations were observed beyond 8 Å.

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“…Cations Si 4+ , Ti 4+ , and P 5+ are assigned to the role of T, and Al 3+ and Fe 3+ are assigned the role of T if there are excess alkalis available for charge balance. The ratio is then obtained by dividing NBO by the total of T cations according to Mysen and Richet (2005) and Giordano et al (2008) using the equation from Mysen et al (1982):…”

Section: Compositional Analysismentioning

confidence: 99%

A New Parameterization of Volcanic Ash Complex Refractive Index Based on NBO/T and SiO₂ Content

et al. 2019

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Radiative transfer models used in remote sensing and hazard assessment of volcanic ash require knowledge of ash optical parameters. Here we characterize the bulk and glass compositions of a representative suite of volcanic ash samples with known complex refractive indices (n + ik, where n is the real part and k is the imaginary part). Using a linear regression model, we develop a new parameterization allowing the complex refractive index of volcanic ash to be estimated from ash SiO2 content or ratio of nonbridging oxygens to tetrahedrally coordinated cations (NBO/T). At visible wavelengths, n correlates better with bulk than with glass composition (both SiO2 and NBO/T), and k correlates better with SiO2 content than with NBO/T. Over a broader spectral range (0.4–19 μm), bulk correlates better than glass composition, and NBO/T generally correlates better than SiO2 content for both parts of the refractive index. In order to understand the impacts of our new parameterization on satellite retrievals, we compared Infrared Atmospheric Sounding Interferometer satellite (wavelengths 3.62–15.5 μm) mass loading retrievals using our new approach with retrievals that assumed a generic (Eyjafjallajökull) ash refractive index. There are significant differences in mass loading using our calculated indices specific to ash type rather than a generic index. Where mass loadings increase, there is often improvement in retrieval quality (corresponding to cost function decrease). This new parameterization of refractive index variation with ash composition will help to improve remote‐sensing retrievals for the rapid identification of ash and quantitative analysis of mass loadings from satellite data on operational timescales.

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Structure of Iron Silicate Glasses and Melts

Cited by 93 publications

References 79 publications

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

Molecular structure of CaO–FeO_x–SiO₂ glassy slags and resultant inorganic polymer binders

A New Parameterization of Volcanic Ash Complex Refractive Index Based on NBO/T and SiO₂ Content

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Structure of Iron Silicate Glasses and Melts

Cited by 93 publications

References 79 publications

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

Three-D Mineralogical Mapping of the Kovdor Phoscorite–Carbonatite Complex, NW Russia: I. Forsterite

Molecular structure of CaO–FeOx–SiO2 glassy slags and resultant inorganic polymer binders

A New Parameterization of Volcanic Ash Complex Refractive Index Based on NBO/T and SiO2 Content

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Product

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Molecular structure of CaO–FeO_x–SiO₂ glassy slags and resultant inorganic polymer binders

A New Parameterization of Volcanic Ash Complex Refractive Index Based on NBO/T and SiO₂ Content