Native alunogen: A Raman spectroscopic study of a well-described specimen

Košek, Filip; Culka, Adam; Žáček, Vladimír; Laufek, František; Škoda, Radek; Jehlička, Jan

doi:10.1016/j.molstruc.2017.12.021

Cited by 13 publications

(9 citation statements)

References 33 publications

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“…The alunogen (tiny colorless platelets) is chemically pure. Positions of the alunogen Raman bands (in parentheses in italics) and their relative intensities show good agreement with major bands reported at~156 (156), ~182 (181), 191 (191),~310 (308),~342 (344),~473 (471), 528 (527),~611 (608),~992 (992),~1086 (1087), and~1127 (1124) cm -1 in the literature (Košek et al 2018). Arsenolite was found in the form of very small (up to 15 lm) octahedral crystals dispersed on the surface of a gypsum crystal and as tiny, loose crystal aggregates.…”

Section: Secondary Mineralssupporting

confidence: 84%

Mineralogy and Weathering of Realgar-Rich Tailings At a Former As-Sb-Cr Mine At Lojane, North Macedonia

Đorđević

Kolitsch

Serafimovski

et al. 2019

The Canadian Mineralogist

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In the Lojane area (North Macedonia) ores of Sb (stibnite), As (realgar), and Cr (chromite) were mined and processed in a metallurgical plant until 1979. Over one million tons of flotation tailings containing As, Sb, and other hazardous substances are located in an open dump site for flotation waste created by the mine. The tailings site is completely unprotected, and its orange color reflects a very high concentration of arsenic (fine-grained realgar superficially altered to pararealgar). In order to better understand the weathering behavior of these tailings, which is necessary to evaluate the environmental risks (mainly from the mobilization of As-Sb-Cr), solid waste material was sampled and studied from the chemical and mineralogical point of view. The material was characterized by inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasmaoptical emission spectrometry (ICP-OES), X-ray diffraction analysis (both single crystal and powder), scanning electron microscopy (SEM) with energy-dispersive microanalysis (EDX), Raman spectroscopy, and transmission electron microscopy (TEM) with selected area electron diffraction (SAED), energy-dispersive X-ray analysis (EDX), and electron energy loss spectrometry (EELS). The studied tailings material is comprised mostly of well-crystallized realgar, gypsum, and quartz, and minor amounts of stibnite, pararealgar, chromite, and sulfur. Very minor pyrite is found within quartz aggregates. The most abundant secondary phase, which forms thin coatings around realgar and stibnite grains, is an As-Sb-Fe-Ca-(Ni)-oxide/ hydroxide in which the As:Sb ratio varies from ca. 2:1 to 1:2.2 and Fe contents are variable.

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Section: Secondary Mineralssupporting

confidence: 84%

Mineralogy and Weathering of Realgar-Rich Tailings At a Former As-Sb-Cr Mine At Lojane, North Macedonia

Đorđević

Kolitsch

Serafimovski

et al. 2019

The Canadian Mineralogist

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“…We observed the positions of ν 1 bands at 1,135 for millosevichite and at 1,079 and 1,100 cm −1 for mikasaite. For both minerals, this is a great shift in the position of the ν 1 band compared with fully hydrated alunogen (992 cm −1 , a difference around 140 cm −1 ) and highly hydrated ferric sulfates (1,031–1,033 cm −1 ). In the case of efremovite, the position is reported at 1,050 cm −1 , which is a distinctive position upshift compared with the corresponding ν 1 band of boussingaultite (at 983 cm −1 ) .…”

Section: Discussionmentioning

confidence: 85%

Raman spectroscopic study of six synthetic anhydrous sulfates relevant to the mineralogy of fumaroles

Košek

Culka

Jehlička

2018

J Raman Spectroscopy

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Fumaroles, vents that emit hot gases and vapor, are an accompanying phenomenon of volcanic activity. Such phenomena are also observed within the framework of self‐ignited burning coal seams and coal heap fires, if less commonly. The high temperatures and chemical reactions between the gas and solid phases are responsible for extensive alteration of surrounding rocks, resulting in mineral encrustations of unusual compositions. Rare anhydrous sulfates (millosevichite, mikasaite, efremovite, godovikovite, sabieite, and steklite) are signature minerals of fumarole encrustations. Comprehensive Raman data for these anhydrous phases are required for the successful identification of natural samples by Raman spectroscopy. Six synthetic equivalents of the natural anhydrous sulfates were prepared by heating of the hydrated analogues and were investigated using both a bench‐top Raman microspectrometer and a portable Raman spectrometer. This comparative approach can help further steps for the successful deployments of miniature Raman tools in situ under field conditions. The studied anhydrous sulfates displayed distinctive Raman spectra of their crystalline phases. Compared with their fully hydrated counterparts, a shifting of bands of the ν1 symmetric stretching mode was observed in the Raman spectra of all samples. Isostructural millosevichite and mikasaite have very distinctive Raman spectra; however, structurally related godovikovite, sabieite, and steklite show very similar spectral shapes. For ammonium‐bearing phases (efremovite, godovikovite, sabieite), the Raman signatures of the NH4 group were observable at >2,800 cm−1 and in the 1,400–1,800 cm−1 region. Our measurements show that the performance of a light‐weight portable Raman spectrometer with near infrared excitation was sufficient for the unambiguous discrimination of the investigated sulfates.

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“…This pattern corresponds to previously reported spectral data. [ 32,60 ] Unless only the ν 1 band is observed, alunogen reveals an unambiguous Raman spectral shape, supported by medium‐intense bands.…”

Section: Resultsmentioning

confidence: 99%

“…Because millosevichite is probably the main component in the sample and this mineral is vulnerable to the absorption of water and phase transitions, alunogen is a possible candidate. [60] A broad multicomponent band shows individual maxima at 1048 or 1078 cm À1 , suggesting the presence of "dehydrated tschermigite" and godovikovite, although the band around 1048 cm À1 was also described for the tetrahydrated phase Al 2 (SO 4 ) 3 Á4H 2 O. [32] Based on laboratory measurements, it was found that the samples contain complex mixtures of both anhydrous and hydrated Al sulfates.…”

Section: High-temperature Associationmentioning

confidence: 99%

Raman spectroscopy of anhydrous and hydrated aluminum sulfates: Experience from burning coal heaps

Košek

Culka

Rousaki

et al. 2022

J Raman Spectroscopy

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Hydrated aluminum‐rich sulfates belong to less widespread secondary minerals on Mars, which are probably connected with hydrothermal alterations. On Earth, such sulfates result from acidic weathering of aluminosilicates, and their formation is controlled by factors such as pH, temperature, or water activity. Physical–chemical conditions can be reconstructed if specific sulfate phases are detected, and therefore, the investigation of sulfate assemblages in high‐temperature settings is important for planetology and exobiology research. Raman spectroscopy is a powerful analytical tool for the discrimination of sulfates, and the degree of hydration, which is a sensitive marker of temperature conditions, can be tracked using this method. However, spectral similarities of sulfates and metastability and rapid transformations may hinder their correct identification. We take advantage of in situ and laboratory Raman spectroscopy to characterize uncommon anhydrous and hydrated Al‐NH4 sulfate mineralogy which forms under elevated temperature at the Anna burning coal waste dump, Alsdorf, Germany, and can be considered as analogous to fumarolic environments. We detected a suite of hydrated Al sulfates (e.g. alunogen, khademite, and tschermigite) in the medium‐temperature zones (~50°C). To minimize possible rehydration processes, we deployed two miniaturized Raman spectrometers (532 and 1064 nm) for field investigations in the high‐temperature zone (~130°C to 150°C). Mixtures of anhydrous (godovikovite and millosevichite) and hydrated phases along with intermediate phases were detected in the field as well as in the laboratory. Such observations are consistent with the premise that the degree hydration of sulfates increase with decreasing temperature. These results confirm that Raman spectroscopy is, despite several analytical challenges, capable of distinguishing Al sulfates, and their hydration states, within complex aggregates and crusts, and future applications in planetary research are promising.

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Native alunogen: A Raman spectroscopic study of a well-described specimen

Cited by 13 publications

References 33 publications

Mineralogy and Weathering of Realgar-Rich Tailings At a Former As-Sb-Cr Mine At Lojane, North Macedonia

Mineralogy and Weathering of Realgar-Rich Tailings At a Former As-Sb-Cr Mine At Lojane, North Macedonia

Raman spectroscopic study of six synthetic anhydrous sulfates relevant to the mineralogy of fumaroles

Raman spectroscopy of anhydrous and hydrated aluminum sulfates: Experience from burning coal heaps

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