Absorption spectrum of dark purple fluorite, Kent deposit, Kazakhstan

Ryskin, A. I.; Федоров, П. П.; Lushchik, A.; Generalov, Miсhail E.; Angervaks, A. E.; Stolyarchuk, Maksim V.; Vasil’chenko, E.; Kudryavtseva, Irina

doi:10.1016/j.jfluchem.2020.109654

Cited by 4 publications

(3 citation statements)

References 18 publications

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“…It is of interest that natural purple fluorites also owe their color to the presence of Ca nanoparticles. Their optical absorption spectra show an intense, broad absorption band near 560 nm that has been suggested to come from Ca metal colloids (Bill and Calas, 1983;Rossman, 2010;Gaft et al, 2020;Ryskin et al, 2020). The same band is found in additively colored synthetic CaF 2 (Angervaks et al, 2018).…”

Section: Discussionmentioning

confidence: 91%

“…The same band is found in additively colored synthetic CaF 2 (Angervaks et al, 2018). This absorption band has a Lorentzian shape, which indicates a plasmon resonance origin (Ryskin et al, 2020 Natural halite exhibits a broad range of colors, navy-blue, blue, purple or colorless arising from various proportions of color centers and Na colloids (Wesełucha-Birczynska et al, 2012). Zelek et al (2014) have shown that this may result from the complex sedimentary geology that governs in the mine the spatial distribution of halite and sylvinite, as 40 K is suspected to be the main radiation source.…”

Section: Discussionmentioning

confidence: 99%

“…This lineshape explains the presence of a long tail extending towards long wavelengths, at the origin of the intense red hue of villiaumite. Such a Lorentzian line-shape characterizes the optical spectra of free neutral Na clusters (Selby et al, 1991), Na nanoparticles in NaCl (Seinen et al, 1994) and NaF (Seifert et al, 1994) or Ca nanoparticles in CaF 2 (Ruiz-Fuertes et al, 2019;Ryskin et al, 2020).…”

Section: Optical Absorption Spectra Of Villiaumitementioning

confidence: 99%

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Sodium nanoparticles in alkali halide minerals: Why is villiaumite red and halite blue?

Calas

Galoisy

Geisler

2021

American Mineralogist

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The presence of metal Na nanoparticles causes the bright, thermally unstable colors of villiaumite, NaF, and halite, NaCl. These nanoparticles have been suspected since a long time to be caused by external irradiation. Metal nanoparticles, often referred to as metal colloids, cause surface plasmon resonance effects, characterized by a single Lorentzian-shaped absorption band.The color of these minerals is due to metal Na nanoparticles of 2.5-3 nm. A key point is that the resonance wavelength, which corresponds to the maximum of the absorption band, is inversely related to the value of the refractive index of the embedding mineral. This causes the position of the main absorption band to be offset downwards by 140 nm in halite relative to villiaumite. As a consequence, the optical transmission window is shifted from the long to the short wavelength domain, explaining the color of blue halite and red villiaumite, respectively. Similar refractive 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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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Optical Absorption Spectra Of Villiaumitementioning

confidence: 99%

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Sodium nanoparticles in alkali halide minerals: Why is villiaumite red and halite blue?

Calas

Galoisy

Geisler

2021

American Mineralogist

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Transformation of calcite CaCO3 to fluorite CaF2 by action of KF solution

Федоров

Luginina

Alexandrov

et al. 2021

Journal of Fluorine Chemistry

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Comparative Study on Gemological and Mineralogical Characteristics and Coloration Mechanism of Four Color Types of Fluorite

et al. 2023

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Fluorite has been attracting the attention of gemstone mineralogists because of its rich color and excellent fluorescence properties. This paper studied fluorite with three color types (blue, green, and white) and five blue-purple fluorites with an alexandrite effect. Through the study of their structure, composition, and spectral characteristics, the gemological and mineralogical characteristics and coloration mechanisms of different color types of fluorites are compared and analyzed. The results show that the color of fluorite is caused by multiple color centers. Blue fluorite is associated with Y3+-F− color center, while green fluorite is associated with a Y3+-Ce2+-F− color center and Sm2+ color center, and white fluorite contains vacancy color center. The color of white fluorite is a mixture of yellow tones produced in visible light and blue fluorescence under UV light. Blue-purple color is caused by the colloid calcium color center and 2F− color center, and its changing from blue-purple to red-purplish (alexandrite effect) are due to colloidal calcium nanoparticles caused by radioactive element Th.

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Absorption spectrum of dark purple fluorite, Kent deposit, Kazakhstan

Cited by 4 publications

References 18 publications

Sodium nanoparticles in alkali halide minerals: Why is villiaumite red and halite blue?

Sodium nanoparticles in alkali halide minerals: Why is villiaumite red and halite blue?

Transformation of calcite CaCO3 to fluorite CaF2 by action of KF solution

Comparative Study on Gemological and Mineralogical Characteristics and Coloration Mechanism of Four Color Types of Fluorite

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