Low temperature spectral studies of Mn3+-bearing andalusite and epidote type minerals in the range 30000–5000 cm−1

Smith, G.; Hålenius, Ulf; Langer, Klaus

doi:10.1007/bf00311284

Cited by 27 publications

(15 citation statements)

References 11 publications

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“…1. Furthermore, spectra of crystal I (at 198.5 gm thickness) and of crystal II (at 10.6 gm thickness) were measured under a cold nitrogen gas flow in a quartz-glass cell (Smith et al 1982) at 193(3)K, 133(8)K, and the X spectrum also at 113(10)K. They are shown in Fig. 2b (crystal I) and curves a (crystal II).…”

Section: Methodsmentioning

confidence: 99%

Polarized electronic absorption spectra of 3d3-configurated tetravalent manganese in octahedral fields of Mn(SeO3)2

Wildner

Langer

1994

Phys Chem Minerals

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Section: Methodsmentioning

confidence: 99%

Polarized electronic absorption spectra of 3d3-configurated tetravalent manganese in octahedral fields of Mn(SeO3)2

Wildner

Langer

1994

Phys Chem Minerals

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“…The incorporation of trace elements is interpreted as the result of (i) oxygen fugacity during crystal growth (Fe), (ii) metamorphic grade, temperature of formation (Ti), or the nature of the protolith (Cr and V) [4]. In the same way, Mn 3+ may substitute for Al 3+ in andalusite [10,11] resulting in the dark green Mn-rich variety of andalusite, formerly known as viridine [2,12]. This may also be the case for epidotes e.g., [13], garnets e.g., [14] and other metamorphic and metasomatic Ca-Al silicates.…”

Section: Introductionmentioning

confidence: 99%

Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece)

et al. 2019

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The Trikorfo area (Thassos Island, Rhodope massif, Northern Greece) represents a unique mineralogical locality with Mn-rich minerals including kyanite, andalusite, garnet and epidote. Their vivid colors and large crystal size make them good indicators of gem-quality materials, although crystals found up to now are too fractured to be considered as marketable gems. The dominant lithology is represented by a garnet–kyanite–biotite–hematite–plagioclase ± staurolite ± sillimanite paragneiss. Thermodynamic Perple_X modeling indicates conditions of ca. 630–710 °C and 7.8–10.4 kbars. Post-metamorphic metasomatic silicate and calc-silicate (Mn-rich)-minerals are found within (i) green-red horizons with a mineralogical zonation from diopside, hornblende, epidote and grossular, (ii) mica schists containing spessartine, kyanite, andalusite and piemontite, and (iii) weakly deformed quartz-feldspar coarse-grained veins with kyanite at the interface with the metamorphic gneiss. The transition towards brittle conditions is shown by Alpine-type tension gashes, including spessartine–epidote–clinochlore–hornblende-quartz veins, cross-cutting the metamorphic foliation. Kyanite is of particular interest because it is present in the metamorphic paragenesis and locally in metasomatic assemblages with a large variety of colors (zoned blue to green/yellow-transparent and orange). Element analyses and UV-near infrared spectroscopy analyses indicate that the variation in color is due to a combination of Ti4+–Fe2+, Fe3+ and Mn3+ substitutions with Al3+. Structural and mineralogical observations point to a two-stage evolution of the Trikorfo area, where post-metamorphic hydrothermal fluid circulation lead locally to metasomatic reactions from ductile to brittle conditions during Miocene exhumation of the high-grade host-rocks. The large variety of mineral compositions and assemblages points to a local control of the mineralogy and fO2 conditions during metasomatic reactions and interactions between hydrothermal active fluids with surrounding rocks.

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“…Spectral band-and step-widths were both 1 nm [2 nm for KzCo2(SeO3)3.2}-I20 ] in the UV/VIS region and 16/ 10 nm [K2Co2(SeO3) 3 9 2H20:20/10 nm] in the NIR region; Local resolution was 40 gm [K2Co2(SeOa)3"2H20:10 gm]. Low-temperature spectra of the two larger samples were recorded at 173 K under a cold nitrogen gas flow in a quartz-glass cell (Smith et al 1982). In addition, spectra of K2Co(SeO3)2 and K2Co2(SeO3)3 with light propagation parallel to the optical axis (' cV) were measured and found to be practically identical with the cr spectra.…”

Section: Methodsmentioning

confidence: 99%

Co2+ in trigonal fields of oxygen based structures: Electronic absorption spectra of buetschliite-type K2Co(SeO3)2, K2Co2(SeO3)3 and zemannite-type K2Co2(SeO3)3 � 2H2O

Wildner

Langer

1994

Phys Chem Minerals

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Abstract. Polarized single crystal absorption spectra, in the spectral range 40 000-5 000 cm-1, were obtained on Co 2+ in trigonally distorted octahedral oxygen fields of buetschliite-type K2Co(SeO3) 2 (I), KzCoz(SeO3) a (II) and zemannite-type K2Co2(SeOa)3.2H20 (III). Site symmetries of Co 2+ are 3m (Dad) in I, 3m (Cav) in II, and 3 (Ca) in III. The spectra can be interpreted on the basis of an electric dipole mechanism, wherein transitions of Co 2 + in the centrosymmetric site in I gain intensity from dynamic removal of the inversion centre by vibronic coupling. In accordance with the elongation of the C006 octahedra along the trigonal axis, the split component E(g) of the ground state 4Wig in octahedral fields is the ground state in all three compounds. Trigonal field parameters Dq~tr~), Dz, Do-and the Racah parameters B have been fitted to the energies of spin allowed transitions (293 K) as follows: I: 744, 94, -16, and 838 cm -1, resp.; II: 647, 227, 42, and 798 cm -1, resp.; III: 667, 181, 21, and 809 cm -1, respectively. Racah parameters C were estimated from the energy of some observed spin-forbidden transitions to be 3770 (I), 3280 (II), and 3465 cm -1 (III). Values of Dq and of the Racah parameters B and C indicate slight differences of Co 2 + -O bonding in I as compared to II and III, with somewhat higher covalency in compounds II and III which contain face-sharing CoO6 octahedra with short Co-Co contacts. Also, in II and III the observed Dz values do not agree with theoretical Dz values, predicted from the magnitude of the mean octahedral distortions.

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Low temperature spectral studies of Mn3+-bearing andalusite and epidote type minerals in the range 30000–5000 cm−1

Cited by 27 publications

References 11 publications

Polarized electronic absorption spectra of 3d3-configurated tetravalent manganese in octahedral fields of Mn(SeO3)2

Polarized electronic absorption spectra of 3d3-configurated tetravalent manganese in octahedral fields of Mn(SeO3)2

Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece)

Co2+ in trigonal fields of oxygen based structures: Electronic absorption spectra of buetschliite-type K2Co(SeO3)2, K2Co2(SeO3)3 and zemannite-type K2Co2(SeO3)3 � 2H2O

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