Inscribed Gems: Material Profiling beyond Visible Examination

Mihailova, Boriana; Schlüter, Jochen; Harter‐Uibopuu, Kaja

doi:10.1515/9783110753301-012

Cited by 2 publications

(9 citation statements)

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“…Phyllosilicates can be found in a variety of cultural-heritage objects such as clay tablets (e.g., Uchida et al, 2015), seals (Zazoff, 1983), earth pigments (e.g., Hradil et al, 2011;Corradini et al, 2021), blotting sand (e.g., Milke, 2012), archeological decoration-related ceramics (e.g., Bersani and Lottici, 2016;El Halim et al, 2018), inscribed gems (e.g., Wang et al, 2013;Bersani and Lottici, 2016;Mihailova et al, 2021, and references therein), and in general as weathering prod-ucts on the surface of common rock-forming silicate minerals (e.g., Velbel, 1993). To achieve a detailed insight into the locality and provenance of such cultural-heritage objects (e.g., Bersani and Lottici, 2016;Mihailova et al, 2021), the determination of the mineral/phase composition as well as of the crystal chemistry within each single mineral constituent is necessary.…”

Section: Introductionmentioning

confidence: 99%

Non-destructive determination of the biotite crystal chemistry using Raman spectroscopy: how far we can go?

Aspiotis¹,

Schlüter

Redhammer

et al. 2022

Eur. J. Mineral.

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Abstract. Raman spectroscopy combined with electron microprobe analysis as well as Mössbauer spectroscopy was applied to a series of 18 samples along the phlogopite (KMg3AlSi3O10(OH)2)–annite (KFe32+AlSi3O10(OH)2) join to establish a truly non-destructive method for crystallochemical characterization of biotite (A1M3T4O10X2, M3 = M1M2M2). The Raman scattering arising from the framework (15–1215 cm−1) and OH-stretching phonon modes (3000–3900 cm−1) was used to build up correlation trends between the Raman spectral features and crystal chemistry of biotite. We show that (a) the contents of MMg, MFe2+, and MFe3+ contents can be quantified with a relative error of ∼ 6 %, ∼ 6 %, and ∼ 8 %, respectively, by combining the integrated intensities of the OH-stretching peaks assigned to various M1M2M2 local configurations with the wavenumber of the MO6 vibrational mode near 190 cm−1; (b) the MTi content can be estimated from the peak position and FWHM (full width at half maximum) of the second strongest TO4-ring mode at ∼ 680 cm−1, with a precision of 22 %; (c) the content of TSi can be estimated from the position of the second peak related to TO4-ring vibrations near 650 cm−1; (d) for phlogopite the TAl content can indirectly be calculated by knowing the amount of TSi, whereas for annite it is hindered by the plausible presence of TFe3+; (e) the AK content can be quantified by the position of the peak generated by T-Ob-T bond-stretching-and-bending vibration at ∼ 730 cm−1; and (f) interlayer-deficient biotites and F-rich phlogopite can be identified via their unique OH-stretching Raman peaks around 3570 cm−1 and 3695 cm−1, respectively. Our results show a potential tool for non-destructive quantitative estimations of the major (Mg, Fe, Si, Al, K) and minor (Ti) elements of the crystal chemistry of the biotite mineral group by using a non-destructive technique such as Raman spectroscopy, although its sensitivity is generally lower than that of electron microprobe analysis and therefore cannot detect trace elements. This is fundamental within the framework of cultural heritage where samples cannot be powdered or disassembled.

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Section: Introductionmentioning

confidence: 99%

Non-destructive determination of the biotite crystal chemistry using Raman spectroscopy: how far we can go?

Aspiotis¹,

Schlüter

Redhammer

et al. 2022

Eur. J. Mineral.

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“…The employed standards were LiF for F, albite for Na, MgO for Mg, corundum for Al, andradite for Fe, vanadinite for Cl, orthoclase for K, MnTiO 3 for Ti and Mn, Cr 2 O 3 for Cr, NiO for Ni, olivenite for Cu, Pb-containing glass for Zn, SrTiO 3 for Sr, and Ba-containing for Ba, and andradite and wollastonite for Si and Ca in the case of serpentine and talc, respectively. The used acquisition times for serpentine were 20 s for Mg, Al, Si, K, Ca, and Fe, 30 s for Na and Ti, 60 s for Cl, Cr, Mn, Ni, Cu, Zn, Sr, and Ba; and 120 s for F, whereas for talc 20 s for Mg, Al, and Si, 30 s for Na, K, Ca, and Ti, 60 s for Cl, Cr, Mn, Fe, Ni, Cu, Zn, Sr, and Ba; and 120 s for F. The chemical The negligible amount of nonmagnesian M-site cations in serpentine 6 is confirmed by this study, but the structure type is reassigned from antigorite 6 to lizardite-rich PS.…”

Section: Wavelength-dispersive Electron Microprobe Analysis (Wd-empa)mentioning

confidence: 99%

“…It has already been proven that classical macroscopic observations of cultural-heritage objects is not accurate enough, especially in the case of opaque rock-based objects. 6 Hence, we have analyzed by Raman spectroscopy four representative nontranslucent historical objects (see Table 3 and inserts in Figure 7). Cylinder seal #1952.0034 has been previously described as soapstone, 2 which is a metamorphic rock consisting of talc intergrown with chlorite and amphiboles.…”

Section: Implications For Cultural Heritagementioning

confidence: 99%

“…They form multiple mineral groups, depending on the stacking sequence of the TO 4 and MO 6 sheets, cationic-site occupancy, and type of interlayer species. 1 Particularly those phyllosilicates with empty interlayer spaces, such as the serpentine-kaolinite and talc-pyrophyllite groups, can be frequently found in cultural-heritage objects, for instance, in Babylonian cylinder seals, 2,3 ancient inscribed gems, [4][5][6] and earth pigments. [7][8][9] The determination of the crystal chemistry and structure of each mineral phase in cultural-heritage objects is essential in the field of provenance studies, 5,6,8 but due to the uniqueness of the specimen, it requires the application of nondestructive and preparation-free analytical methods such as Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…1 Particularly those phyllosilicates with empty interlayer spaces, such as the serpentine-kaolinite and talc-pyrophyllite groups, can be frequently found in cultural-heritage objects, for instance, in Babylonian cylinder seals, 2,3 ancient inscribed gems, [4][5][6] and earth pigments. [7][8][9] The determination of the crystal chemistry and structure of each mineral phase in cultural-heritage objects is essential in the field of provenance studies, 5,6,8 but due to the uniqueness of the specimen, it requires the application of nondestructive and preparation-free analytical methods such as Raman spectroscopy. This method is particularly attractive because (i) phonon modes are sensitive to both chemistry and structure, (ii) crystalline and amorphous compounds can be equally identified, and (iii) micrometer-sized particles/areas (down to a few μm) can be easily probed if a microscope is used.…”

Section: Introductionmentioning

confidence: 99%

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Raman spectroscopy for crystallochemical analysis of Mg‐rich layered silicates: Serpentine and talc

Aspiotis,

Schlüter,

Hildebrandt

et al. 2023

J Raman Spectroscopy

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A series of 10 talc (nominally MMg3TSi4O10X(OH)2) and 22 serpentine (nominally MMg3TSi2O5X(OH)4) minerals have been studied by Raman spectroscopy and electron microprobe analysis (EMPA) to establish quantitative relationships between the content of octahedrally coordinated M‐site cations and Raman peak parameters, which would allow for noninvasive material profiling. We show that in the case of talc, the position of the strong and well‐resolved peak near 360 cm−1, related to MO6 vibrations, as well as the integrated intensities of the OH‐stretching Raman signals (3600–3750 cm−1) can be used to determine the amount of MMg and M(Fe2+ + Mn2+) with a precision similar to that of EMPA. In the case of serpentine, the overall shape of the Raman scattering arising from OH‐stretching modes (3600–3750 cm−1) can be initially used to distinguish between the different polymorphs: antigorite, chrysotile, and lizardite, as well as the lizardite‐/chrysotile‐rich polygonal/polyhedral serpentine varieties and then, the full width at half maximum (FWHM) of the strongest MO6 peak at ~380 cm−1 can be used to estimate MMg content in each of the analyzed polymorphs/varieties and a relative error of 5%. In addition, MFe2+ amount in chrysotile and chrysotile‐rich polygonal serpentine can be quantified by FWHM of the peak near 230 cm−1 with a relative error of 5%, whereas MFe2+ amount in antigorite can be derived from FWHM of the peak near 130 cm−1 with similar relative uncertainties. We demonstrate the effectiveness of our approach on two types of rock‐based cultural‐heritage objects, cylinder seals and inscribed gems, where sampling is prohibitive.

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Inscribed Gems: Material Profiling beyond Visible Examination

Cited by 2 publications

References 0 publications

Non-destructive determination of the biotite crystal chemistry using Raman spectroscopy: how far we can go?

Non-destructive determination of the biotite crystal chemistry using Raman spectroscopy: how far we can go?

Raman spectroscopy for crystallochemical analysis of Mg‐rich layered silicates: Serpentine and talc

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