Electronic absorption spectra of Cr3+ ions in natural clinopyroxenes

Khomenko, V. M.; Platonov, A. N.

doi:10.1007/bf00307404

Cited by 21 publications

(11 citation statements)

References 6 publications

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“…The large band centered at 570 nm, attributed to intervalence Fe 2+ –Fe 3+ charge transfer and the absorption above 900 nm attributed to Fe 2+ are of relatively low intensity (more intense in JDXX021 spectrum) . The main causes of the natural green color of all the studied samples are Cr 3+ and Fe 3+ in octahedral coordination . However, the samples PP10 and PP15_1 are not presenting any detectable with EDXRF amount of chromium or higher iron concentrations compared with the other seven measured samples (refer again to Table ).…”

Section: Resultsmentioning

confidence: 77%

“…More precisely, the large band at 380 nm, the double sharp band at around 440 nm and the broad bands at around 620 and 850 nm were attributed to Fe 3+ in octahedral coordination . The bands centered at around 450 and 640 nm as well as the shoulder at around 690 nm are attributed to Cr 3+ in octahedral coordination . Total absorption is observed in the UV range below 330 nm in both samples.…”

Section: Resultsmentioning

confidence: 78%

“…Al/(Al + Fe) [8] 0.99 0.86 0.93 0.94 0.93 0.97 0.93 0.87 0.65 Na/(Na + Ca) [8] 0.95 0.62 0.85 0.86 0.87 0.90 0.63 0.54 0.86 to Cr 3+ in octahedral coordination. [29][30][31] Total absorption is observed in the UV range below 330 nm in both samples. The large band centered at 570 nm, attributed to intervalence Fe 2+ -Fe 3+ charge transfer and the absorption above 900 nm attributed to Fe 2+ are of relatively low intensity (more intense in JDXX021 spectrum).…”

Section: Resultsmentioning

confidence: 99%

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Gem quality and archeological green ‘jadeite jade’ versus ‘omphacite jade’

Coccato

Karampelas²,

Wörle

et al. 2014

J Raman Spectroscopy

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Raman spectroscopy was used for the characterization of seven gem quality green ‘jade’ samples and three green ‘jade’ samples of archaeological importance. The results were also compared with those acquired by other nondestructive techniques such as classical gemology, energy‐dispersive X‐ray fluorescence (EDXRF), ultraviolet‐visible‐near infrared (UV‐Vis‐NIR) in absorption, Fourier transform infrared spectroscopy (FTIR) in absorption and micro‐FTIR in reflectance. Five samples of gem quality and two samples of archaeological interest were found to be ‘jadeite jade’, whereas two samples of gem quality and one sample of archaeological interest were ‘omphacite jade’. Raman spectroscopy is found to be the most efficient method for their characterization. The results were confirmed with EDXRF and micro‐FTIR in reflectance. Data acquired using classical gemology, UV‐Vis‐NIR absorption and FTIR absorption spectroscopy were similar on ‘omphacite jade’ and ‘jadeite jade’. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Gem quality and archeological green ‘jadeite jade’ versus ‘omphacite jade’

Coccato

Karampelas²,

Wörle

et al. 2014

J Raman Spectroscopy

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show abstract

“…The reflectance spectra of Adams [1975] and White et al [1971] do not show this level of complexity in the 0.65 μm region. However, high‐resolution transmission spectra, as well as the current reflectance spectra, do show multiple bands in the 0.65 μm region [ Mao et al , 1972; Rossman , 1980; Khomenko and Platonov , 1985]. The 0.455 and 0.65 μm absorption features are only apparent in the HCP samples which contain >0.9 wt % Cr 2 O 3 .…”

Section: Site Occupancies By Transition Series Elementsmentioning

confidence: 99%

“…6 -4 do show multiple bands in the 0.65 mm region [Mao et al, 1972;Rossman, 1980;Khomenko and Platonov, 1985]. The 0.455 and 0.65 mm absorption features are only apparent in the HCP samples which contain >0.9 wt % Cr 2 O 3 .…”

Section: Cr-bearing Pyroxenesmentioning

confidence: 99%

Pyroxene reflectance spectra: Minor absorption bands and effects of elemental substitutions

Cloutis

2002

J.‐Geophys.‐Res.

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[1] Reflectance spectra of a suite of compositionally diverse pyroxenes exhibit variable spectral properties which are associated with various elemental substitutions. Those associated with transition series elements, such as Cr, Ti, V, and Mn, give rise to a number of minor absorption bands in the visible spectral region and, in some cases (e.g., Mn), at longer wavelengths. Substitutions by other cations, such as Li and Zr, do not result in distinct absorption bands. The spectra of these pyroxenes are dominated by the transition series elements that may be present in the samples. The visible wavelength region of lowcalcium pyroxene reflectance spectra exhibit a number of absorption bands which are attributable to Fe 2+ spin-forbidden crystal field transitions. Fe 2+ -Fe 3+ intervalence charge transfer absorption bands near 0.77 mm are common in terrestrial pyroxenes which contain both ferrous and ferric iron. Collectively, these results indicate that the presence of various transition series elements can be detected in reflectance spectra and that their oxidation states and site occupancies can also be determined on the basis of unique spectral characteristics present in their reflectance spectra, thereby greatly increasing the range of compositional information which can be derived from analysis of their reflectance spectra. INDEX TERMS: 3620 Mineralogy and Petrology: Crystal chemistry; 3670 Mineralogy and Petrology: Minor and trace element

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Jarosite occurrence in the Deccan Volcanic Province of Kachchh, western India: Spectroscopic studies on a Martian analog locality

et al. 2016

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The sulfate mineral jarosite is considered a key indicator of hydrous, acidic, and oxidizing conditions on the surface of early Mars. Here we report an analog terrestrial locality hosting jarosite from Matanumadh, Kachchh, western India, using detailed spectroscopic studies on weathered basalts of the Deccan Volcanic Province and overlying tuffaceous shales and sandstones of the Matanumadh Formation. Hyperspectral data in the visible/near‐infrared (350–2500 nm) to midinfrared (4000–400 cm−1) region of the electromagnetic spectrum and X‐ray diffraction patterns have been acquired on samples collected from the field to detect and characterize the hydrous sulfate and phyllosilicate phases present at the studied site. Hydrous sulfates occur in association with Al‐rich phyllosilicates (kaolinite) that overlie a zone of Fe/Mg smectites in altered basalts. Jarosite is found within both saprolitic clay horizons altered from the basalt and within variegated sandstone and shale/clay units overlying the saprolite; it mostly occurs as secondary veins with or without gypsum. Jarosite is also seen as coatings on kaolinite clasts of varying shapes and sizes within the tuffaceous variegated sandstone unit. We argue that the overall geological setting of the Matanumadh area, with this unusual mineral assemblage developing within altered basalts and in the overlying sedimentary sequence, mimics the geological environment of many of the identified jarosite localities on Mars and can be considered as a Martian analog from this perspective.

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Electronic absorption spectra of Cr3+ ions in natural clinopyroxenes

Cited by 21 publications

References 6 publications

Gem quality and archeological green ‘jadeite jade’ versus ‘omphacite jade’

Gem quality and archeological green ‘jadeite jade’ versus ‘omphacite jade’

Pyroxene reflectance spectra: Minor absorption bands and effects of elemental substitutions

Jarosite occurrence in the Deccan Volcanic Province of Kachchh, western India: Spectroscopic studies on a Martian analog locality

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