Spectroscopic study of inclusions in gem corundum from Mercaderes, Cauca, Colombia

Zeug, Manuela; Vargas, Andrés Ignacio Rodríguez; Nasdala, Lutz

doi:10.1007/s00269-016-0851-4

Cited by 7 publications

(12 citation statements)

References 75 publications

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“…Low compressive stresses in the host garnet next to graphite inclusions can be explained in terms of stress distribution in the host–inclusion system. As a consequence, pressure in the host can never match that in the inclusion . The lack of significant overpressure for the garnet host adjacent to a coesite inclusion is known …”

Section: Resultsmentioning

confidence: 99%

Graphite‐bearing mineral assemblages in the mantle beneath Central Aldan superterrane of North Asian craton: combined confocal micro‐Raman and electron microprobe characterization

Николенко

Sharygin

Alifirova

et al. 2017

J Raman Spectroscopy

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Mantle‐derived lherzolitic and harzburgitic Cr‐pyropes from lamprophyres of the Chompolo field (Central Aldan superterrane, North Asian Craton) were studied using micro‐Raman spectroscopy and electron microprobe microanalysis. These garnets enclose graphite coexisting with forsterite, diopside, Ba‐Cl‐phlogopite, tschermakite, rutile, magnesiochromite, Mg‐ilmenite, apatite, chalcopyrite, dolomite, magnesite and lindsleyite inclusions. The PT conditions of residence of graphite‐bearing assemblage in the mantle were estimated, using a combination of mineral thermometers and barometers, to be as high as 2.87–3.55 GPa and 710–770 °C. Generally, graphite within inclusions is well ordered; D1 and D2 disordered bands in its spectra are restricted to inclusion edges. The residual pressure up to 2.1 GPa was inferred for graphite assuming pressure dependence of the G‐band upshift (1580 cm−1 at ambient conditions vs 1588.6 cm−1 at 2.1 GPa). Disordered graphite most likely appears due to the stress‐induced distortion of the fully ordered graphite crystal structure. The distortion results from difference in the thermoelastic properties of graphite inclusions and their garnet hosts exposed to decompression during ascent to the surface with lamprophyre magma. The mineralogy of inclusions in the studied garnets strongly suggests an episode(s) of metasomatism by carbon‐rich agent(s) (COH‐fluid or carbonatitic melt) in the lithospheric mantle of the Central Aldan superterrane, which was coeval with the formation of graphite inclusions and the host pyropes. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Graphite‐bearing mineral assemblages in the mantle beneath Central Aldan superterrane of North Asian craton: combined confocal micro‐Raman and electron microprobe characterization

Николенко

Sharygin

Alifirova

et al. 2017

J Raman Spectroscopy

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“…The possible inclusions present in the corundum have been extensively studied in the literature. − In our investigation, we refer mostly to rutile-based inclusions , producing blue halos as a consequence of the Be-thermodiffusion treatment that our gems underwent in Thailand. This study aims to understand the chemical mechanism of blue halo formation and to characterize the physicochemical aspects of the mineral systems generated during the heat process.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of Be-Thermodiffusion in Rutile Inclusions of Fancy Sapphires

Rossi

Biondi

Rizzi

et al. 2022

Crystal Growth & Design

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The solid-state chemistry of inclusions in Al2O3 is of high relevance in several applications, spanning from photonics to materials engineering and gemology. Be-thermodiffusion is a common treatment of corundum crystals to improve their optical properties. The chemistry of such a high-temperature process is still unclear. Particularly, the interconversion between corundum host and guest inclusion species involves many chemical species and several steps, whose knowledge would guide the tuning of corundum chemical preparation. Herein, 43 thermodiffusion-treated sapphires are investigated, with a focus on 14 samples endowed with blue halos, via optical microscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) quantitative chemical analyses, Raman microspectroscopy, and X-ray powder diffraction. This study searches for the snapshots of the chemical path and then recomposes them to propose a novel chemical mechanism in which Be reduces TiO2 inclusion, which is then converted, mediated by iron ions, to several titanates. The chemical mechanism is discussed in terms of applications not limited to only gemology but to any derivative corundum crystal preparation.

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“…The PL spectra of parisite–(Ce) presented in the present study may assist in verifying the identity of this mineral, using the characteristic emission “fingerprint” that is due to the particular crystal-field splitting of Nd 3+ -related electronic transitions in parisite–(Ce) (cf. Lenz et al 2013 ; Zeug et al 2017 ).…”

Section: Discussionmentioning

confidence: 99%

“…The PL spectra of parisite-(Ce) presented in the present study may assist in verifying the identity of this mineral, using the characteristic emission "fingerprint" that is due to the particular crystal-field splitting of Nd 3+ -related electronic transitions in parisite-(Ce) (cf. Lenz et al 2013;Zeug et al 2017). Guastoni et al (2009) determined positions of the ν 1 (CO 3 ) band of a parisite-(Ce) crystal at~1083, 1093 and 1101 cm −1 , which is remarkably different to ν 1 (CO 3 ) band positions obtained from fluorcarbonate minerals of the present study.…”

Section: Analytical Artefacts Caused By Pl Emissionmentioning

confidence: 99%

The parisite–(Ce) enigma: challenges in the identification of fluorcarbonate minerals

et al. 2020

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A multi-methodological study was conducted in order to provide further insight into the structural and compositional complexity of rare earth element (REE) fluorcarbonates, with particular attention to their correct assignment to a mineral species. Polycrystals from La Pita Mine, Municipality de Maripí, Boyacá Department, Colombia, show syntaxic intergrowth of parisite–(Ce) with röntgenite–(Ce) and a phase which is assigned to B3S4 (i.e., bastnäsite-3–synchisite-4; still unnamed) fluorcarbonate. Transmission electron microscope (TEM) images reveal well-ordered stacking patterns of two monoclinic polytypes of parisite–(Ce) as well as heavily disordered layer sequences with varying lattice fringe spacings. The crystal structure refinement from single crystal X-ray diffraction data – impeded by twinning, complex stacking patterns, sequential and compositional faults – indicates that the dominant parisite–(Ce) polytype M1 has space group Cc. Parisite–(Ce), the B3S4 phase and röntgenite–(Ce) show different BSE intensities from high to low. Raman spectroscopic analyses of parisite–(Ce), the B3S4 phase and röntgenite–(Ce) reveal different intensity ratios of the three symmetric CO3 stretching bands at around 1100 cm−1. We propose to non-destructively differentiate parisite–(Ce) and röntgenite–(Ce) by their 1092 cm−1 / 1081 cm−1 ν1(CO3) band height ratio.

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Spectroscopic study of inclusions in gem corundum from Mercaderes, Cauca, Colombia

Cited by 7 publications

References 75 publications

Graphite‐bearing mineral assemblages in the mantle beneath Central Aldan superterrane of North Asian craton: combined confocal micro‐Raman and electron microprobe characterization

Graphite‐bearing mineral assemblages in the mantle beneath Central Aldan superterrane of North Asian craton: combined confocal micro‐Raman and electron microprobe characterization

Mechanism of Be-Thermodiffusion in Rutile Inclusions of Fancy Sapphires

The parisite–(Ce) enigma: challenges in the identification of fluorcarbonate minerals

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