Two-phonon excitations in IR and NIR spectra of alunites

Breitinger, Dietrich K.; Schukow, H.; Belz, H. H.; Mohr, J.; Schwab, R.

doi:10.1016/s0022-2860(98)00724-8

Cited by 9 publications

(2 citation statements)

References 3 publications

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“…Comparison of spectra from deuterated and non-deuterated synthetic alunites indicates that absorptions in this spectral region can be assigned to the m 3SO4 stretch and d OH bend overtone absorptions (Breitinger et al, 1999). These same assignments have been suggested for similar absorptions in jarosite (Bishop and Murad, 2005).…”

Section: Spectroscopysupporting

confidence: 60%

Mineralogical and chemical characteristics of some natural jarosites

Desborough

Smith

Lowers

et al. 2010

Geochimica et Cosmochimica Acta

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This paper presents a detailed study of the mineralogical, microscopic, thermal, and spectral characteristics of jarosite and natrojarosite minerals. Systematic mineralogic and chemical examination of a suite of 32 natural stoichiometric jarosite and natrojarosite samples from diverse supergene and hydrothermal environments indicates that there is only limited solid solution between Na and K at low temperatures, which suggests the presence of a solvus in the jarosite-natrojarosite system at temperatures below about 140°C. The samples examined in this study consist of either end members or coexisting end-member pairs of jarosite and natrojarosite. Quantitative electron-probe microanalysis data for several natural hydrothermal samples show only end-member compositions for individual grains or zones, and no detectable alkali-site deficiencies, which indicates that there is no hydronium substitution within the analytical uncertainty of the method. In addition, there is no evidence of Fe deficiencies in the natural hydrothermal samples. Hydronium-bearing jarosite was detected in only one relatively young supergene sample suggesting that terrestrial hydronium-bearing jarosites generally are unstable over geologic timescales.Unit-cell parameters of the 20 natural stoichiometric jarosites and 12 natural stoichiometric natrojarosites examined in this study have distinct and narrow ranges in the a-and c-cell dimensions. There is no overlap of these parameters at the 1r level for the two end-member compositions. Several hydrothermal samples consist of fine-scale (2-10 lm) intimate intergrowths of jarosite and natrojarosite, which could have resulted from solid-state diffusion segregation or growth zoning due to variations in the Na/K activity ratio of hydrothermal solutions. Published by Elsevier Ltd.

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Section: Spectroscopysupporting

confidence: 60%

Mineralogical and chemical characteristics of some natural jarosites

Desborough

Smith

Lowers

et al. 2010

Geochimica et Cosmochimica Acta

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“…Combinations of the ν 1 , ν 2 , ν 3 , and ν 4 sulfate bands are also likely contributors to these features. By measuring spectra of alunite at 88 K, Breitinger et al (1999) were able to resolve eight discernable bands in the fi rst overtone region. Upon deuteration, three of these bands are shifted and fi ve remain, suggesting that fi ve are overtones and combinations of the sulfate vibrations and three are overtones and combinations of the OH bands.…”

Section: Overtone and Combination Modesmentioning

confidence: 99%

The visible and infrared spectral properties of jarosite and alunite

Bishop

2005

American Mineralogist

218

175

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The visible and infrared spectral properties of two natural jarosite minerals and a suite of synthetic jarosites and alunite samples are described here. The fundamental stretching and bending vibrations observed in the infrared region for SO 4 2-and OH -are compared with the near-infrared overtones and combinations of these vibrations. Shifts were observed in the SO 4 2-and OH -bands for Al 3+ vs. Fe 3+ at the octahedral sites and K + vs. Na + at the "A" (frequently monovalent) sites. Crystal-fi eld theory bands were observed for jarosite near 435, 650, and 900-925 nm and were compared to those of iron oxides. , and 440-675 cm -1 , respectively) for jarosite would be most useful for detecting these minerals using remote sensing on Earth or Mars. These minerals are important indicators of alteration processes, and this study contributes toward combined visible/near-infrared and mid-infrared spectral detection of these two alunite-group minerals.

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