Titanium as Free Oxide and Substituted Forms in Kaolinites and other Soil Minerals

Dolcater, D. L.; Syers, J. K.; Jackson, M. L.

doi:10.1346/ccmn.1970.0180202

Cited by 75 publications

(54 citation statements)

References 9 publications

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“…The titanium oxide content has been estimated from the measured elemental Ti concentration (obtained by XRF), which is converted to TiO 2 using the appropriate molar mass conversion factor (1.67). This should be considered as an upper-limit estimate as some of the titanium in mineral dust is present as a substitution element in aluminosilicates (Dolcater et al, 1970). Figure 7 presents the correlation between TiO 2 and the TDM.…”

Section: Titanium Oxide Contentmentioning

confidence: 99%

Mapping the physico-chemical properties of mineral dust in western Africa: mineralogical composition

et al. 2014

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Abstract. In the last few years, several ground-based and airborne field campaigns have allowed the exploration of the properties and impacts of mineral dust in western Africa, one of the major emission and transport areas worldwide. In this paper, we explore the synthesis of these observations to provide a large-scale quantitative view of the mineralogical composition and its variability according to source region and time after transport.This work reveals that mineral dust in western Africa is a mixture of clays, quartz, iron and titanium oxides, representing at least 92 % of the dust mass. Calcite ranged between 0.3 and 8.4 % of the dust mass, depending on the origin. Our data do not show a systematic dependence of the dust mineralogical composition on origin; this is to be the case as, in most of the instances, the data represent the composition of the atmospheric burden after 1-2 days after emission, when air masses mix and give rise to a more uniform dust load. This has implications for the representation of the mineral dust composition in regional and global circulation models and in satellite retrievals.Iron oxides account for 58 ± 7 % of the mass of elemental Fe and for between 2 and 5 % of the dust mass. Most of them are composed of goethite, representing between 52 and 78 % of the iron oxide mass. We estimate that titanium oxides account for 1-2 % of the dust mass, depending on whether the dust is of Saharan or Sahelian origin.The mineralogical composition is a critical parameter for estimating the radiative and biogeochemical impact of mineral dust. The results regarding dust composition have been used to estimate the optical properties as well as the iron fractional solubility of Saharan and Sahelian dust.Data presented in this paper are provided in numerical form upon email request while they are being turned into a public database, the Dust-Mapped Archived Properties (DUST-MAP), which is an open repository for compositional data from other source regions in Africa and worldwide.

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Section: Titanium Oxide Contentmentioning

confidence: 99%

Mapping the physico-chemical properties of mineral dust in western Africa: mineralogical composition

et al. 2014

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“…All of the sodium and calcium was assumed to be exchangeable. Titanium was included in the structural formula on the basis of a report (Dolcater et al, 1970) that more than half of the Ti in two bentonites was structural and not in a separate phase. Manganese was not included in the structural formulae because the MnOz concentrations were insignificant.…”

Section: Structural Formulaementioning

confidence: 99%

Role of Iron Reduction in The Conversion of Smectite to Illite in Bentonites in the Disturbed Belt, Montana

Eslinger

Highsmith

Albers

et al. 1979

Clays and clay miner.

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Abstraet--Cretaceous bentonites were collected in outcrop from the Sweetgrass Arch and the Disturbed Belt in Montana. The mixed-layer illite-smectite (I/S) components of the bentonites from the Sweetgrass Arch have from 0 to 25% illite layers and no detectable structural Fe 2+, whereas the samples from the Disturbed Belt have from about 25 to 90% illite layers, and all contain Fe 2+. A positive correlation (r = 0.89) exists between the percentage of structural iron that is Fe z+ and the amount of fixed interlayer K in the US.The higher percentage of illite layers in the samples from the Disturbed Belt is attributed to reactions related to elevated temperatures caused by burial beneath thrust sheets. The increase in Fe2+/Fe 3+ with increasing percentages of illite layers is tentatively attributed to a redox reaction involving the oxidation of organic matter. Although there is no statistical evidence for an increase in octahedral charge with an increase in illite layers when all the samples are considered together, iron reduction may have contributed as much as 10 to 30% of the increase in total structural-charge that occurred in any given sample during metamorphism. The remaining structural charge increase can be attributed to the substitution of Al 3+ for Si 4 § in the tetrahedral sites.

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“…The form under which Ti occurs in altered rocks may influence the geochemical behavior of Ti during alteration. Titanium impurities have been suggested to occur either substituted in the kaolinite structure (Dolcater et al 1970, Weaver 1976, Rengasamy 1976 or as associated phases in kaolinitic materials (Jepson 1988). Because all kaolins contain significant amounts of titanium, the location of this element may be used as an indicator of the geochemical conditions during alteration and sedimentation processes.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Approach for Investigating the Status and Mobility of Ti in Kaolinitic Materials

Malengreau

Müller

Calas

1995

Clays and clay miner.

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Abstract--The form under which Ti occurs in kaolinitic materials from various environments has been investigated using second derivative diffuse reflectance spectroscopy. The position of the absorption edge may be used as a diagnostic band to determine Ti-phases (anatase, futile, Ti-gels). Ti-oxides may be detected in kaolins, down to 0.1 wt. % Ti02. Diffuse reflectance spectra show the presence of Ti-gel-like phases occluded in sedimentary kaolinite particles. These phases, which record conditions at the time of kaolinite growth, constitute the first direct evidence of Ti mobility at the scale of mineral assemblages and question the substitution of Ti for AI in kaolinite. The nature of the Ti-oxides associated with kaolinite particles gives some constraints on the temperature conditions of hydrothermal kaolins, the evolution of sedimentary kaolin during basin diagenesis and the source of parental material in soil kaolins.

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Titanium as Free Oxide and Substituted Forms in Kaolinites and other Soil Minerals

Cited by 75 publications

References 9 publications

Mapping the physico-chemical properties of mineral dust in western Africa: mineralogical composition

Mapping the physico-chemical properties of mineral dust in western Africa: mineralogical composition

Role of Iron Reduction in The Conversion of Smectite to Illite in Bentonites in the Disturbed Belt, Montana

Spectroscopic Approach for Investigating the Status and Mobility of Ti in Kaolinitic Materials

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