Natural bentorite—Cr3+ derivate of ettringite: determination of crystal structure

Seryotkin, Yurii V.; Sokol, Ella V.; Kokh, Svetlana N.; Sharygin, Victor V.

doi:10.1007/s00269-019-01022-4

Cited by 14 publications

(14 citation statements)

References 49 publications

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“…We assigned the 547 cm −1 and 857 cm −1 bands, observed in the ettringite spectrum, to the Al-OH stretching and bending vibration of the Al(OH) 6 3− unit, respectively, similar to previous reports [24,25,27]. Thus, the bands at 537 and 757 cm −1 in bentorite were most likely related to the vibration modes of Cr-OH in Cr(OH) 6 3− [5,28]. Frost et al [26], analyzing the spectra of natural ettringite, assigned the band at~760 cm −1 to the hydroxyl deformation mode of Al-OH units.…”

Section: Raman Spectroscopysupporting

confidence: 85%

“…Furthermore, structure refinements of the Al end-member (ettringite) and two Cr 3+ bearing ettringite crystals (with maximum Cr occupation at the octahedral site = 27.5%) were reported by Seryotkin et al [4] for the same locality. Recently, the same group of authors performed a structural investigation of polycrystalline bentorite using synchrotron powder diffraction data, collected at room temperature (295 K) [5]. Their work confirmed that ettringite and bentorite were isostructural and that Al 3+ ↔Cr 3+ substitution took place without significant structural modifications.…”

Section: Introductionmentioning

confidence: 85%

“…Dark-violet, prismatic bentorite crystals up to 150 µm in size, associated with calcite and ettringite, were found in low temperature veins within spurrite marble in the Arad Stone Quarry in the Negev Desert, Israel (Figure 1a,b). The studied rocks belonged to the pyrometamorphic Hatrurim Complex (Mottled Zone), which is distributed on both sides of the Dead Sea Transform Fault [5,[8][9][10][11][12][13][14]. Besides the main rock forming minerals, spurrite and calcite, the minor concentrations of ye'elimite, shulamitite-sharyginite, brownmillerite, and fluorapatite-fluorellestadite were identified in the analyzed samples.…”

Section: The Occurrence and Paragenesis Of Bentoritementioning

confidence: 99%

“…This explains an extremely rare occurrence of bentorite in nature and difficulties in finding crystals with good quality and size for the structural (single crystal) study. Hitherto, this phase was found only in pyrometamorphic rocks of the Hatrurim Complex [1,[3][4][5].…”

Section: Introductionmentioning

confidence: 99%

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Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

et al. 2019

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The crystal structure of bentorite, ideally Ca6Cr2(SO4)3(OH)12·26H2O, a Cr3+ analogue of ettringite, is for the first time investigated using X-ray single crystal diffraction. Bentorite crystals of suitable quality were found in the Arad Stone Quarry within the pyrometamorphic rock of the Hatrurim Complex (Mottled Zone). The preliminary semi-quantitative data on the bentorite composition obtained by SEM-EDS show that the average Cr/(Cr + Al) ratio of this sample is >0.8. Bentorite crystallizes in space group P31c, with a = b = 11.1927(5) Å, c =21.7121(10) Å, V = 2355.60(18) Å3, and Z = 2. The crystal structure is refined, including the hydrogen atom positions, to an agreement index R1 = 3.88%. The bentorite crystal chemical formula is Ca6(Cr1.613Al0.387)Σ2[(SO4)2.750(CO3)0.499]Σ3.249(OH)11.502·~25.75H2O. The Raman spectra of bentorite from two different localities exhibit the presence of the main stretching and bending vibrations related to the sulfate group at 983 cm−1 (ν1), 1109 cm−1 (ν3), 442 cm−1 (ν2), and 601 cm−1 (ν4). Moreover, the presence of bands assigned to the symmetric Cr(OH)63− stretching mode and hydroxyl deformation vibrations of Cr–OH units at ~540 cm−1 and ~757 cm−1, respectively, may be used to distinguish between ettringite and bentorite. In situ high temperature single crystal XRD experiments show that the decomposition of bentorite starts at ca. 45 °C and that a dehydroxylation product similar to metaettringite is formed.

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Section: Raman Spectroscopysupporting

confidence: 85%

Section: Introductionmentioning

confidence: 85%

Section: The Occurrence and Paragenesis Of Bentoritementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

et al. 2019

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“…The results for natural clinker-like rocks support the conclusion of Achtenbosch et al (2003) [17] that the primary raw materials are the main source of Zn, Cd, Cu, Cr in cement. However, unlike most cements and concretes, the Cr-enrichment in our case is characteristic of the sediment [86,[135][136][137].…”

Section: Trace Elements Partitioning: Implications For Te Storage In mentioning

confidence: 99%

Mineralogical Diversity of Ca2SiO4-Bearing Combustion Metamorphic Rocks in the Hatrurim Basin: Implications for Storage and Partitioning of Elements in Oil Shale Clinkering

et al. 2019

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This is the first attempt to provide a general mineralogical and geochemical survey of natural Ca 2 SiO 4 -bearing combustion metamorphic (CM) rocks produced by annealing and decarbonation of bioproductive Maastrichtian oil shales in the Hatrurim Basin (Negev Desert, Israel). We present a synthesis of data collected for fifteen years on thirty nine minerals existing as fairly large grains suitable for analytical examination. The Hatrurim Ca 2 SiO 4 -bearing CM rocks, which are natural analogs of industrial cement clinker, have been studied comprehensively, with a focus on several key issues: major-and trace-element compositions of the rocks and their sedimentary precursors; mineral chemistry of rock-forming phases; accessory mineralogy; incorporation of heavy metals and other trace elements into different phases of clinker-like natural assemblages; role of trace elements in stabilization/destabilization of Ca 2 SiO 4 polymorphic modifications; mineralogical diversity of Ca 2 SiO 4 -bearing CM rocks and trace element partitioning during high-temperature-low-pressure anhydrous sintering. The reported results have implications for mineral formation and element partitioning during high-temperature-low-pressure combustion metamorphism of trace element-loaded bituminous marine chalky sediments ("oil shales") as well as for the joint effect of multiple elements on the properties and hydration behavior of crystalline phases in industrial cement clinkers.

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High- and low-temperature mineral phases from the pyrometamorphic rocks, Jordan

Khoury

2020

Arab J Geosci

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Natural bentorite—Cr3+ derivate of ettringite: determination of crystal structure

Cited by 14 publications

References 49 publications

Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

Raman Spectroscopy and Single-Crystal High-Temperature Investigations of Bentorite, Ca6Cr2(SO4)3(OH)12·26H2O

Mineralogical Diversity of Ca2SiO4-Bearing Combustion Metamorphic Rocks in the Hatrurim Basin: Implications for Storage and Partitioning of Elements in Oil Shale Clinkering

High- and low-temperature mineral phases from the pyrometamorphic rocks, Jordan

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