Raman and optical spectroscopic investigation of gem-quality smoky quartz crystals

Fridrichová, Jana; Bačík, Peter; Illášová, Ľudmila; Kozáková, Petra; Škoda, Radek; Pulišová, Zuzana; Fiala, Abdelali

doi:10.1016/j.vibspec.2016.03.028

Cited by 9 publications

(2 citation statements)

References 15 publications

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“…Only a few Slovak minerals, including quartz var. smoky quartz [8,9], sphalerite [8,10], pyrite [8], garnet var. almandine [8], hematite [8], and corundum var.…”

Section: Introductionmentioning

confidence: 99%

Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobšiná, Slovakia

et al. 2019

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Andradite, variety demantoid, is a rare gem mineral. We describe gem-quality garnet crystals from serpentinized harzburgites from Dobšiná, Slovakia which were faceted. Both the andradite samples were transparent, with a vitreous luster and a vivid green color. They were isotropic with refractive indices >1.81. The measured density ranged from 3.82 to 3.84 g·cm−3. Andradite var. demantoid appeared red under Chelsea filter observation. Both samples contained fibrous crystalline inclusions with the typical “horsetail” arrangement. The studied garnet had a strong Fe3+ dominant andradite composition with 1.72–1.85 apfu Fe3+, Cr3+ up to 0.15 apfu, Al3+ 0.03 to 0.04 apfu, V3+ up to 0.006 apfu substituted for Fe3+, Mn2+ up to 0.002 apfu, and Mg up to 0.04 apfu substituted for Ca. Raman spectrum of garnet showed three spectral regions containing relatively strong bands: I—352–371 cm−1, II—816–874 cm−1, and III—493–516 cm−1. The optical absorption spectrum as characterized by an intense band at 438 nm and two broad bands at 587 and 623 nm and last one at 861 nm, which were assigned to Fe3+ and Cr3+. Transmission was observed in the ultraviolet spectral region (<390 nm), near the infrared region (700–800 nm), and around 530 nm in the green region of visible light, resulting in the garnet’s green color.

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“…Only a few Slovak minerals, including quartz var. smoky quartz [8,9], sphalerite [8,10], pyrite [8], garnet var. almandine [8], hematite [8], and corundum var.…”

Section: Introductionmentioning

confidence: 99%

Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobšiná, Slovakia

et al. 2019

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“…The Raman spectrum measured after quenching from 893 K(Fig. 3)shows a phase assemblage of -Fe 2 O 3 maghemite(Chamritski and Burns 2005), orthro-enstatite(Lin 2003), quartz(Fridrichová et al 2016), and some remaining olivine with weakened signals as compared with those before heating. As compared with Fo 89 Fa 11 , the Fo 58 Fa 42 sample dissociates at a relatively lower temperature due to Fe incorporation Abdu et al (2008).…”

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confidence: 99%

High-temperature and high-pressure Raman spectra of Fo89Fa11 and Fo58Fa42 olivines: Iron effect on thermodynamic properties

Liu

Guo

Smyth

et al. 2021

American Mineralogist

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The intrinsic anharmonicity plays an important role in the thermodynamic properties of minerals at the high-temperature conditions of the mantle. To investigate the effect of iron on the thermodynamic properties of olivine, the most abundant mineral in the upper mantle, we measured in situ high-temperature and high-pressure Raman spectra of natural Fo 89 Fa 11 and synthetic Fo 58 Fa 42 samples. Fo 58 Fa 42 dissociates to enstatite + quartz + Fe 2 O 3 (+ Fe) at 893 K. All the Raman-active modes systematically shift to lower frequencies at elevated temperature, whereas to higher frequencies with increasing pressure. The A g mode at approximately 960 cm-1 is more sensitive to the variations of temperature and pressure than the other internal modes. The crystal-field splitting of the vibrational energy states gets slightly weakened at high temperature, but strengthened at elevated pressure. We calculated the isobaric ( iP) and isothermal ( iT) mode Grüneisen parameters for these olivine samples. The intrinsic anharmonic parameters (a i) are in negative for both the lattice and internal vibrations, and our calculations indicate that the intrinsic anharmonicity makes positive contributions to the thermodynamic properties of olivine at high temperatures, such as the internal energy (U), heat capacities (C V and C P) and entropy (S). Iron incorporation further increases the magnitudes of these anharmonic contributions. In addition, the Fe effect on the intrinsic anharmonicity may also apply to other thermodynamic properties in olivine, such as equations of state and equilibrium isotopic fractionations, which are relevant and important to constrain many physical and chemical properties in the upper mantle. This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Insights into the oxidation behavior of Ni–25Cr–10Fe–xSi (x = 1, 2, 3, 4 wt%) alloys at 1000°C in ambient air

Jia

Pan

et al. 2022

Materials & Corrosion

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The isothermal oxidation behavior of Ni-25Cr-10Fe-xSi (x = 1, 2, 3, 4 wt%) alloys at 1000°C in ambient air was investigated. The thermodynamics and kinetics of the oxidation behavior were analyzed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, Raman spectroscopy, and the Thermo-Calc software with the TTNI8 database. The weight gain per unit area of the four alloys showed a parabolic relationship with the oxidation time. The weight gain of the oxides decreased with the addition of larger amounts of Si from 1 to 3 wt%; however, this trend was lost when excessive addition of Si (4 wt% Si) was added. A sufficient amount of discontinuously distributed SiO 2 precipitates resulted in better oxidation resistance and adhesion properties than continuous SiO 2 layers. The spallation resistance of the oxide scales is believed to be mainly dependent on the distribution of the SiO 2 layer rather than the content of SiO 2 ; 3 wt% is a reasonable reference value for Si addition for improving the oxidation resistance of Ni-25Cr-10Fe alloys.

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Raman and optical spectroscopic investigation of gem-quality smoky quartz crystals

Cited by 9 publications

References 15 publications

Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobšiná, Slovakia

Gem-Quality Green Cr-Bearing Andradite (var. Demantoid) from Dobšiná, Slovakia

High-temperature and high-pressure Raman spectra of Fo89Fa11 and Fo58Fa42 olivines: Iron effect on thermodynamic properties

Insights into the oxidation behavior of Ni–25Cr–10Fe–xSi (x = 1, 2, 3, 4 wt%) alloys at 1000°C in ambient air

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