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Highlights: [•] We have studied the molecular structure of the mineral glaucocerinite. [•] Using a combination of Raman and infrared spectroscopy. [•] The mineral is one of the hydrotalcite supergroup of natural layered double hydroxides. [•] The observation of multiple bands provides evidence for the reduction in symmetry of the sulphate anion from T d to C 2v. [•] Vibrational spectroscopy enables aspects of the molecular structure of glaucocerinite to be determined. [ABSTRACT FROM AUTHOR]

Review: 64 refs. [ABSTRACT FROM AUTHOR]

We have studied the mineral analcime using a combination of scanning electron microscopy with energy dispersive spectroscopy and vibrational spectroscopy. The mineral analcime Na2(Al4SiO4O12)·2H2O is a crystalline sodium silicate. Chemical analysis shows the mineral contains a range of elements including Na, Al, Fe2+ and Si. The mineral is characterized by intense Raman bands observed at 1052, 1096 and 1125cm-1. The infrared bands are broad; nevertheless bands may be resolved at 1006 and 1119cm-1. These bands are assigned to SiO stretching vibrational modes. Intense Raman band at 484cm-1 is attributed to OSiO bending modes. Raman bands observed at 2501, 3542, 3558 and 3600cm-1 are assigned to the stretching vibrations of water. Low intensity infrared bands are noted at 3373, 3529 and 3608cm-1. The observation of multiple water bands indicate that water is involved in the structure of analcime with differing hydrogen bond strengths. This concept is supported by the number of bands in the water bending region. Vibrational spectroscopy assists with the characterization of the mineral analcime. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have studied the boron containing mineral ezcurrite Na4B10O17⋅7H2O. [•] Using electron microscopy and vibrational spectroscopy. [•] Both tetrahedral and trigonal boron units are observed. [•] Identify separate bands for the stretching bands of the two boron isotopes. [•] The number of water bending modes is in harmony with the number of water stretching vibrations. [ABSTRACT FROM AUTHOR]

The mineral kidwellite, a hydrated hydroxy phosphate of ferric iron and sodium of approximate formula NaFe93+(PO4)6(OH)11⋅3H2O, has been studied using a combination of electron microscopy with EDX and vibrational spectroscopic techniques. Raman spectroscopy identifies an intense band at 978 cm-1 and 1014 cm-1. These bands are attributed to the PO4³- ν1 symmetric stretching mode. The ν3 antisymmetric stretching modes are observed by a large number of Raman bands. The series of Raman bands at 1034, 1050, 1063, 1082, 1129, 1144 and 1188 cm-1 are attributed to the ν3 antisymmetric stretching bands of the PO4³- and HOPO3²- units. The observation of these multiple Raman bands in the symmetric and antisymmetric stretching region gives credence to the concept that both phosphate and hydrogen phosphate units exist in the structure of kidwellite. The series of Raman bands at 557, 570, 588, 602, 631, 644 and 653 cm-1are assigned to the PO4³- ν2 bending modes. The series of Raman bands at 405, 444, 453, 467, 490 and 500 cm-1 are attributed to the PO4³- and HOPO3²- ν4 bending modes. The spectrum is quite broad but Raman bands may be resolved at 3122, 3231, 3356, 3466 and 3580 cm-1. These bands are assigned to water stretching vibrational modes. The number and position of these bands suggests that water is in different molecular environments with differing hydrogen bond distances. Infrared bands at 3511 and 3359 cm-1 are ascribed to the OH stretching vibration of the OH units. Very broad bands at 3022 and 3299 cm-1 are attributed to the OH stretching vibrations of water. Vibrational spectroscopy offers insights into the molecular structure of the phosphate mineral kidwellite. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have studied the so-called mineral manasseite. [•] Now defined as hydrotalcite Mg6Al2(OH)16(CO3)⋅4H2O. [•] Hydrogen bond distances varied between 2.61 and 3.00Å. [•] Two Raman bands at 1059 and 1064cm−1 are observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Homogeneous cation distribution in LDH was for the first time recognized via MIR and NIR. [•] Relative contents of various hydroxyl species were theoretically calculated. [•] Hydroxyl bands of MIR and NIR were fitted into different species. [•] The fitting results accords well with the theoretical calculations. [Copyright &y& Elsevier]