New Data on Epidote-Supergroup Minerals: Unusual Chemical Compositions, Typochemistry, and Raman Spectroscopy

Варламов, Д. А.; Ермолаева, В. Н.; Чуканов, Н. В.; Jančev, S.; Вигасина, М. Ф.; Plechov, P. Yu.

doi:10.1134/s1075701519080130

Cited by 7 publications

(7 citation statements)

References 15 publications

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“…Most likely, the authors misidentified their sample, since no chemical or X-ray analyses can confirm their assumption. The Raman spectra of allanite identified in Valea Pianu samples (Figure 3) better resemble a Cr-rich allanite-group mineral reported by Varlamov et al [57], and the Raman frequencies fit perfectly with those reported by Chukanov and Vigasina [58] for allanite-(Ce). A tentative assignment of the Raman modes can be made by comparing it with epidote spectrum [59].…”

Section: Allanitesupporting

confidence: 81%

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

et al. 2020

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In the current study, different heavy minerals typical of gold placer deposits were identified by means of micro-Raman spectroscopy, and their chemical composition analyzed and discussed (garnet, kyanite, staurolite, zircon, allanite, monazite, xenotime, rutile, anatase, cassiterite, titanite, barite). Even complex solid solution series, such as those of garnets, can be deciphered with the aid of systematic trends observed in Raman line frequencies. The ν1 mode in garnets will shift from high to low frequencies as a function of the ionic radius of the X2+ cation, from Mg2+, to Fe2+ and Mn2+, while the presence of Ca2+ will make the band to be shifted strongly to even lower wavenumbers. This approach has successfully been taken to differentiate between polymorph triplets such as kyanite-sillimanite-andalusite and rutile-anatase-brookite. Minerals under consideration with high contents of REE, U and Th are affected by intensive metamictization, particularly zircon and titanite. Raman peak features, such as shape, symmetry and intensity, respond to this radiation damage of the lattice and enable fine-tuning of these heavy minerals, such as in the case of fluorite (fetid fluorite).

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Section: Allanitesupporting

confidence: 81%

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

et al. 2020

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“…8 (curve a) together with spectra of epidote and clinozoisite. The assignment of the Raman bands of epidote-group minerals is as follows (Varlamov et al , 2019; Kasatkin et al , 2020a; 2020b): 1000–1100 cm –1 is assigned to stretching vibrations of Si–O–Si fragments in the Si 2 O 7 groups; and the 850 to 1000 cm –1 range to stretching vibrations of apical Si–O bonds. The range between 650 and 710 cm –1 is assigned to M –O⋅⋅⋅H bending vibrations.…”

Section: Resultsmentioning

confidence: 99%

“…The Si–O–Si angle in the Si 2 O 7 group depends on the force characteristics of a cation in the A 2 site. In particular, the substitution of Ca with REE results in the lowering of both the Si–O–Si angle and frequency of stretching vibrations of Si–O–Si fragments (Varlamov et al , 2019). As a result, the band at 1090–1094 cm –1 in the Raman spectra of REE-free epidote-group minerals shifts to lower frequencies in the Raman spectrum of REE-bearing mukhinite.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the main schemes of isomorphic substitutions in these minerals are ΣREE + Mg ↔ Ca + Al and V+Cr ↔ Al. The simultaneous occurrence of significant amounts of Cr and REE in a mineral of the epidote supergroup was noted by us in the rocks of the dyke complex of the Kosyu ore field, Chetlassky Kamen, Middle Timan Mts., which belongs to the Riphean Chetlas hypabyssal complex of alkaline picrites and carbonatites (Varlamov et al, 2019). This potentially new mineral is characterised by low aluminium contents.…”

Section: Discussionmentioning

confidence: 99%

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Crystal chemistry and origin of REE-bearing mukhinite from carbonate veins of the Svetlinsky gold deposit, South Urals, Russia

Korinevsky

Чуканов

Aksenov

et al. 2022

MinMag

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A rare earth element (REE)-, Cr- and Mg-bearing variety of the vanadium epidote-group mineral mukhinite occurs in a calcite–dolomite carbonatite dyke cutting metamorphosed volcano-sedimentary rocks exposed in the walls of the quarry of the Svetlinsky gold deposit, South Urals. This mineral was found in a paragene assemblage including native sulphur, phlogopite and fluorophlogopite, together with accessory pyrite, other sulfides and sulfosalts, gold, Cr- and V-bearing muscovite, margarite, Cr- and V-bearing dravite, fluoro-tremolite, actinolite, fluoro-pargasite, anhydrite, apatite, uranium hydroxides, V-rich titanite, V- and Nb-rich rutile, spinel and corundum. The contents of ΣREE2O3 and V2O3 in mukhinite vary in the ranges of 4.01–9.69 and 5.34–7.46 wt.%, respectively. A Raman spectrum of REE-rich mukhinite is provided. The main schemes of isomorphic substitutions in mukhinite are ΣREE + Mg ↔ Ca + Al and V+Cr ↔ Al. The crystal structure of REE-rich mukhinite has been studied by single-crystal X-ray diffraction analysis. The mineral is monoclinic, with the space group P21/m, and unit-cell parameters are: a = 8.8972(11) Å, b = 5.6221(6) Å, c = 10.1519(12) Å, β = 115.169° and V = 459.60(11) Å3. The crystal structure of REE-rich mukhinite is similar to that of its synthetic analogue; the refined crystal-chemical formula of the sample studied is (Z = 2): { A 1Ca A 2(Ca0.8REE0.2)}{ M 1(Al0.95Cr0.05) M 2Al M 3[(V,Cr)3+0.40Al0.35Mg0.25]}(Si2O7)(SiO4)O(OH).

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“…According to Nagashima et al (2021), the most intense Raman band at 975 cm -1 in the spectrum of heflikite can be assigned to the Si-O stretching mode, the band at 568 cm -1 to the Si-O-Si bending mode, and the features in the regions around 100 cm -1 and 240 cm -1 are most probably connected to heavy-cation vibrations and external silicate modes. Varlamov et al (2019) assigned bands from the range 300-600 cm -1 collectively to the M-O stretching vibrations and bending vibrations of silicate anions. In their studies on various epidotesupergroup minerals, Varlamov et al (2019) assigned the band in the range of 1020-1200 cm -1 to stretching vibrations of the Si-O-Si bridges.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Heflikite, ideally Ca₂(Al₂Sc)(Si₂O₇)(SiO₄)O(OH), the first scandium epidote-supergroup mineral from Jordanów Śląski, Lower Silesia, Poland and from Heftetjern, Tørdal, Norway

Pieczka,

Kristiansen,

Stachowicz

et al. 2024

MinMag

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Heflikite, the first Sc-dominant epidote-supergroup mineral, was discovered in two occurrences. The holotype was found in a granitic pegmatite associated with rodingite-like calc-silicate rocks and metasomatised granitic bodies exposed in a serpentinite quarry at Jordanów Śląski near Sobótka, Lower Silesia, SW Poland. The cotype comes from the Heftetjern pegmatite, Tørdal region, Norway. The holotype is composed of (in wt.%): 35.69 SiO2, 0.22 TiO2, 21.98 Al2O3, 6.12 Sc2O3, 0.07 V2O3, 1.10 Fe2O3, 0.11 Y2O3, 1.55 La2O3, 4.05 Ce2O3, 0.31 Pr2O3, 1.53 Nd2O3, 0.40 Sm2O3, 0.11 EuO, 0.56 Gd2O3, 0.14 MnO, 3.56 FeO, 0.16 MgO, 19.16 CaO and 1.78 H2O(+)calc.; total 98.60. The cotype contains: 34.92 SiO2, 0.44 TiO2, 0.82 SnO2, 19.13 Al2O3, 4.79 Sc2O3, 1.96 Fe2O3, 2.55 La2O3, 7.39 Ce2O3, 0.48 Pr2O3, 0.67 Nd2O3, 0.12 EuO, 0.61 Gd2O3, 0.13 MnO, 5.97 FeO, 17.66 CaO and 1.73 H2O(+)calc.; total 99.37. The compositions correspond to the following empirical formulae: (Ca1.729Ce0.125La0.048Nd0.046Gd0.016Sm0.012Pr0.010Y0.005Eu2+0.003)Σ1.994[(Al2.182Sc0.449Fe3+0.070V3+0.005)Σ2.706(Fe2+0.251Mg0.020Mn0.010)Σ0.281Ti0.014]Σ3.001(Si3.006O11)O(OH) and (Ca1.644Ce0.235La0.082Nd0.021Gd0.018Pr0.015Eu2+0.004)Σ1.019[(Al1.958Sc0.362Fe3+0.128)Σ2.448(Fe2+0.434Mn0.009)Σ0.443(Ti0.029Sn0.029)Σ0.058]Σ2.949(Si3.033O11)O(OH), respectively, and to the ideal formula Ca2(Al2Sc)(Si2O7)(SiO4)O(OH). The crystal structure of the holotype was refined in the monoclinic system with an R1 index of 8.62%. The crystal-structure refinement indicates exclusively Si occupied T sites, Al occupied M1 and M2 sites, and a Ca occupied A1 site. The M3 site is filled predominantly by trivalent cations, mainly Sc3+, with divalent cations (mainly Fe2+) as minor occupants. The A2 site is filled mostly by Ca with minor amounts of rare earth elements (REE). The holotype heflikite crystallised from metasomatic fluids that infiltrated a contact between the granitic pegmatite and the surrounding rodingite-type calc-silicate rocks and serpentinites. The fluids that introduced Sc into the pegmatite could have been either hydrothermal or related to low-grade regional metamorphism that postdated the formation of the pegmatite. The cotype heflikite formed during the late-stage hydrothermal crystallisation of the Sc-enriched granitic pegmatite.

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New Data on Epidote-Supergroup Minerals: Unusual Chemical Compositions, Typochemistry, and Raman Spectroscopy

Cited by 7 publications

References 15 publications

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

Crystal chemistry and origin of REE-bearing mukhinite from carbonate veins of the Svetlinsky gold deposit, South Urals, Russia

Heflikite, ideally Ca₂(Al₂Sc)(Si₂O₇)(SiO₄)O(OH), the first scandium epidote-supergroup mineral from Jordanów Śląski, Lower Silesia, Poland and from Heftetjern, Tørdal, Norway

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New Data on Epidote-Supergroup Minerals: Unusual Chemical Compositions, Typochemistry, and Raman Spectroscopy

Cited by 7 publications

References 15 publications

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

Micro-Raman—A Tool for the Heavy Mineral Analysis of Gold Placer-Type Deposits (Pianu Valley, Romania)

Crystal chemistry and origin of REE-bearing mukhinite from carbonate veins of the Svetlinsky gold deposit, South Urals, Russia

Heflikite, ideally Ca2(Al2Sc)(Si2O7)(SiO4)O(OH), the first scandium epidote-supergroup mineral from Jordanów Śląski, Lower Silesia, Poland and from Heftetjern, Tørdal, Norway

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Heflikite, ideally Ca₂(Al₂Sc)(Si₂O₇)(SiO₄)O(OH), the first scandium epidote-supergroup mineral from Jordanów Śląski, Lower Silesia, Poland and from Heftetjern, Tørdal, Norway