Silmarilly Bahfenne

A Review of the Vibrational Spectroscopic Studies of Arsenite, Antimonite, and Antimonate Minerals

Abstract This review focuses on the vibrational spectroscopy of the compounds and minerals containing the arsenite, antimonite, and antimonate anions. The review collects and correlates the published data.

Mid-infrared and near-infrared spectroscopic study of selected magnesium carbonate minerals containing ferric iron-Implications for the geosequestration of greenhouse gases.

The proposal to remove greenhouse gases by pumping liquefied CO(2) several kilometres below the ground implies that many carbonate containing minerals will be formed. Among these minerals brugnatellite and coalingite are probable. Two ferric ion bearing minerals brugnatellite and coalingite with a hydrotalcite-like structure have been characterised by a combination of infrared and near-infrared (NIR) spectroscopy. The infrared spectra of the OH stretching region are characterised by OH and water stretching vibrations. Both the first and second fundamental overtones of these bands are observed in the NIR spectra in the 7030-7235 cm(-1) and 10,490-10,570 cm(-1) regions. Intense (CO(3))(2-) symmetric and antisymmetric stretching vibrations support the concept that the carbonate ion is distorted. The position of the water bending vibration indicates the water is strongly hydrogen bonded in the mineral structure. Split NIR bands at around 8675 and 11,100 cm(-1) indicate that some replacement of magnesium ions by ferrous ions in the mineral structure has occurred. Near-infrared spectroscopy is ideal for the assessment of the formation of carbonate minerals.

A vibrational spectroscopic study of hydrated Fe3+ hydroxyl-sulfates; polymorphic minerals butlerite and parabutlerite

Raman and infrared spectra of two polymorphous minerals with the chemical formula Fe3+(SO4)(OH)·2H2O, monoclinic butlerite and orthorhombic parabutlerite, are studied and the spectra assigned. Observed bands are attributed to the (SO4)2- stretching and bending vibrations, hydrogen bonded water molecules, stretching and bending vibrations of hydroxyl ions, water librational modes, Fe-O and Fe-OH stretching vibrations, Fe-OH bending vibrations and lattice vibrations. The O-H⋯O hydrogen bond lengths in the structures of both minerals are calculated from the wavenumbers of the stretching vibrations. One symmetrically distinct (SO4)2- unit in the structure of butlerite and two symmetrically distinct (SO4)2- units in the structure of parabutlerite are inferred from the Raman and infrared spectra. This conclusion agrees with the published crystal structures of both mineral phases.

A near-infrared and Raman spectroscopic study of the mineral richelsdorfite Ca2Cu5Sb[Cl|(OH)6|(AsO4)4]·6H2O

Raman spectroscopy has enabled insights into the molecular structure of the richelsdorfite Ca(2)Cu(5)Sb[Cl|(OH)(6)|(AsO(4))(4)]·6H(2)O. This mineral is based upon the incorporation of arsenate or phosphate with chloride anion into the structure and as a consequence the spectra reflect the bands attributable to these anions, namely arsenate or phosphate and chloride. The richelsdorfite Raman spectrum reflects the spectrum of the arsenate anion and consists of ν(1) at 849, ν(2) at 344 cm(-1), ν(3) at 835 and ν(4) at 546 and 498 cm(-1). A band at 268 cm(-1) is attributed to CuO stretching vibration. Low wavenumber bands at 185 and 144 cm(-1) may be assigned to CuCl TO/LO optic vibrations.

The Mineral Nealite Pb4Fe2+(AsO3)2Cl4 · 2H2O—A Raman Spectroscopic Study

ABSTRACT The mineral nealite Pb4Fe2+(AsO3)2Cl4 · 2H2O is of archaeological significance as it is man made mineral formed through the dumping of mine wastes in the sea. The mineral has been studied by Raman spectroscopy. Raman spectroscopy identifies intense Raman bands at 708 and 732 cm−1 assigned to stretching vibrations. In addition low intensity bands are observed at 604 and 632 cm−1, which are attributed to symmetric and antisymmetric stretching modes. Low intensity Raman band is observed at 831 cm−1 and is assigned to the stretching vibration. Intense Raman bands at 149 and 183 cm−1 are attributed to M-Cl stretching vibrations. Raman spectroscopy identifies arsenic anions in different oxidation states in the mineral. The molecular structure of the mineral nealite, as indicated by Raman spectroscopy, is more complex than has been reported by previous studies.

Raman spectroscopic study of the antimonate mineral romeite

Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca(2)Sb(2)O(6)(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at approximately 518 cm(-1) for roméite is assigned to the SbO nu(1) symmetric stretching mode and the band at 466 cm(-1) to the SbO nu(3) antisymmetric stretching mode. The Raman band at 303 cm(-1) is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples.

Vibrational spectroscopic study of the antimonate mineral bindheimite Pb2Sb2O6(O,OH)

Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the antimonate mineral bindheimite Pb(2)Sb(2)O(6)(O,OH). The mineral is characterised by an intense Raman band at 656 cm(-1) assigned to SbO stretching vibrations. Other lower intensity bands at 664, 749 and 814 cm(-1) are also assigned to stretching vibrations. This observation suggests the non-equivalence of SbO units in the structure. Low intensity Raman bands at 293, 312 and 328c m(-1) are assigned to the OSbO bending vibrations. Infrared bands at 979, 1008, 1037 and 1058 cm(-1) may be assigned to deltaOH deformation modes of SbOH units. Infrared bands at 1603 and 1640 cm(-1) are assigned to water bending vibrations, suggesting that water is involved in the bindheimite structure. Broad infrared bands centred upon 3250 cm(-1) supports this concept. Thus the true formula of bindheimite is questioned and probably should be written as Pb(2)Sb(2)O(6)(O,OH,H(2)O).

Raman spectroscopic study of the mineral thorikosite Pb3(OH)(SbO3,AsO3)Cl2 : a mineral of archaeological significance

ABSTRACT The mineral thorikosite Pb3(OH)(SbO3,AsO3)Cl2 is named after the ancient city of Thorikos, in the region of Attica, where the ancient mine sites dating back to the bronze ages are found. Raman spectra of the antimonite-bearing mineral thorikosite Pb3(OH)(SbO3,AsO3)Cl2 were studied and were related to the structure of the mineral. Two intense Raman peaks were observed at 596 and 730 cm−1 and were assigned to the Sb3+O3 and As3+O3 stretching vibrations. A peak at 1085 cm−1 is assigned to the Sb3+OH deformation mode. Raman band at 325 cm−1 is assigned to an OAsO bending vibration of the As3+O3 units, and the bands at 269 and 275 cm−1 are attributed to the OSbO bending modes of the Sb3+O3 units. The intense Raman bands at 112 and 133 cm−1 are associated with PbCl stretching modes. Minerals such as nealite and thorikosite are minerals of archaeological significance. Yet no spectroscopic studies of these minerals had been undertaken.

Raman spectroscopic study of the antimonate mineral brizziite NaSbO3

Raman spectra of antimonate mineral brizziite NaSbO3 were studied and related to the structure of the mineral. Two sharp bands at 617 and 660 cm−1 are attributed to the SbO symmetric stretching mode. The reason for two symmetric stretching vibrations depends upon the bonding of the SbO units. The band at 617 cm−1 is assigned to bonding through the Sb and 660 cm−1 to bonding through the oxygen. The low intensity band at 508 cm−1is ascribed to the SbO antisymmetric stretching vibration. Low intensity bands were found at 503, 526 and 578 cm−1. Sharp Raman bands observed at 204, 230, 307 and 315 cm−1 are assigned to OSbO bending modes. Raman spectroscopy enables a better understanding of the molecular structure of the mineral brizziite.

Single-crystal Raman spectroscopy of natural schafarzikite FeSb2O4 from Pernek, Slovak Republic

Abstract We present the first single-crystal Raman spectra of the mineral schafarzikite FeSb2O4 from the Pernek locality of the Slovak Republic. In addition, Raman spectra of the natural mineral apuanite Fe2+Fe43+Sb4O12S, originating from the Apuan Alps in Italy, as well as spectra of synthetic ZnSb2O4 and the arsenite mineral trippkeite (CuAs2O4) are presented for the first time. The spectra of the antimonite minerals are characterized by a strong band in the region 660-680 cm-1 with shoulders on either side, and a band of medium intensity near 300 cm-1. The spectrum of the arsenite mineral is characterized by a medium band near 780 cm-1 with a shoulder on the high wavenumber side and a strong band at 370 cm-1. Mode assignments are proposed based on the spectral comparison between the compounds, symmetry modes of the bands and prior literature. The single-crystal spectra of schafarzikite showed good mode separation, allowing bands to be assigned to the symmetry species of A1g, B1g, B2g, or Eg.