Serpentinites are rocks, often used in buildings, formed in large extent by minerals of the serpentine group: chrysotile, antigorite, lizardite, and polygonal serpentine. The fibrous type (e.g. chrysotile) of serpentine group minerals, along with several amphibole varieties (e.g. actinolite and tremolite), are the major components of asbestos family. The exposure to fine fibrous asbestos powder is linked to diseases such as pleural mesothelioma and asbestosis. The identification of the main varieties of the serpentine group, laminated or fibrous, becomes an issue of great interest for public health. This work introduces an analytical strategy able to distinguish the different serpentine polymorphs directly on the sample, allowing the analysis within their textural environment, evidencing at the micrometer scale the mineral reactions of the phases. Samples coming from the Koniambo massif (Grande Terre Island, New Caledonia) were studied by means of optical microscopy, scanning electron microscopy-energy dispersive X-ray spectroscopy, and Raman spectroscopy. Raman peaks observed in the high wavenumber spectral range of 3550-3850 cm À1 , associated with OH stretching vibrations, allow the discrimination of the all four serpentine varieties. The relationship between the different varieties of serpentine, at a micrometric scale, in complex samples, has been investigated by two-dimensional Raman mapping.

The Raman spectrum of diopside has been calculated by using three purely Density Functional Theory (DFT) Hamiltonians (PBE, WCPBE, LDA), the Hartree-Fock Hamiltonian (HF) and three hybrid HF/DFT ones (B3LYP, WC1LYP, PBE0). A comparison has been done between the calculated frequencies with those measured by Raman spectroscopy on a natural sample, along with several different orientations and beam polarizations, or retrieved from literature; such a comparison demonstrated the excellent performances of the hybrid Hamiltonians in reproducing the vibrational spectrum of the mineral, in line with what it is generally observed in literature concerning other mineral phases. In particular, the mean average absolute discrepancies of the calculated frequencies with respect to the experimental data were: 3.2 (WC1LYP), 4.7 (B3LYP), 6.5 (PBE0), 18.0 (PBE), 9.7 (WCPBE), 7.3 (LDA) and 40.6 cm -1 (HF). The very good quality of the WC1LYP results, allowed for a reliable assignment of all of the experimentally observed Raman signals, and the corresponding assignments to specific patterns of atomic vibrational motion (normal modes).

Plagioclase undergoes complex exsolution and ordering and phase transition processes during their evolution in nature, and this has hindered attempts to define simple trends relating the major peaks of their Raman spectra with composition. Here, the peak position and linewidth of major Raman features have been calibrated for a set of 20 plagioclases, spanning from albite to anorthite in composition, with symmetry and ordering states that were already well characterized. Point group symmetry is the most important factor determining the Raman peak behaviour with composition, though C true1¯, I true1¯, and P true1¯ plagioclases show different trends for the position of the main peak νa at ~500 cm−1. Using a simplifying approach, which merges the effect of Al–Si ordering and incommensurate modulations, a method has been developed to estimate the plagioclase composition from calibration of a few determinative Raman peaks. This makes use of the wavenumber difference Δab between the most intense peaks νa and νb around 500 cm−1, the linewidth Гa of the strongest νa peak, and the wavenumber difference Δcb between νc and νb peaks, where νc is a Raman feature at ~560–580 cm−1. The calibration was completed from data sets composed of spectra from metamorphic to pegmatitic plagioclase. The results were then tested against a further data set, mostly made by volcanic plagioclase. In most samples, the difference between electron micro probe analysis (EMPA) and Raman compositions is less than 5%. Higher residuals (beyond 10%) are observed for intermediate plagioclase, suggesting that some differences in Δab exist between volcanic and metamorphic plagioclase of intermediate compositions. The Raman compositional results for a plagioclase from Marsili submarine volcano agree with composition and zoning found from the analysis by laser ablation.

After cellulose, lignin is the most abundant plant-derived polymer in nature. It provides mechanical support to plants, but it has also a defense role against pests and diseases, thanks to antioxidant, bactericidal, and antifungal properties, deriving from its polyphenolic nature. Huge quantities of technical lignins are obtained during several industrial processes and they actually represent a waste of paper pulp and bioethanol industry. Although in the last decades many efforts have been directed to obtain lignin valorization in several fields and for diverse applications, this biobased polymer is still largely underutilized. In particular, very little is known about the possibility to exploit its antioxidant, antifungal, and antibacterial properties in the agronomical field. On the other hand, pest control is often achieved by using copper-based pesticides, but environmental and health issues urge for novel solutions implying reduced copper content. We here describe novel hybrid organic–inorganic materials obtained by combining copper­(II) salts with two types of technical lignins. Cu-containing materials (lignin@Cu) have been characterized by different techniques, including X-ray powder diffraction and transmission electron spectroscopy analyses, revealing nanocrystals of brochantite (Cu4SO4(OH)6) grown in the lignin matrix. Lignin@Cu was tested for its antifungal and antibacterial profile against a vast panel of pathogens of agronomical interest. Furthermore, preliminary tests on crops in a greenhouse were performed: lignin@Cu had better performances than a commercial pesticide based on copper­(II) hydroxide on tomato plants against Rhizoctonia solani, indicating a great potential of these materials as plant protection products.

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Albite is one of the most common minerals in the Earth's crust, and its polymorphs can be found in rocks with different cooling histories. The characteristic spectrum of vibration of the albite mineral reflects its structural Si/Al ordering. In this study, we report on the comparison between the Raman spectra measured on a natural and fully ordered (as deduced on the basis of single‐crystal X‐ray diffraction data) ‘low albite’, NaAlSi3O8, and those calculated at the hybrid Hartree–Fock/density functional theory level by employing the WC1LYP Hamiltonian, which has proven to give excellent agreement between calculated and experimentally measured vibrational wavenumbers in silicate minerals. All the 39 expected Ag modes are identified in the Raman spectra, and their wavenumbers and intensities, in different scattering configurations, correspond well to the calculated ones. The average absolute discrepancy |trueboldΔboldv¯| is ~3.4 cm−1, being the maximum discrepancy |Δv|max ~ 10.3 cm−1. The very good quality of the WC1LYP results allows for reliable assignments of the Raman features to specific patterns of atomic vibrational motion. Copyright © 2015 John Wiley & Sons, Ltd.

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The crystal structure of three C2/c clinopyroxenes with composition (Ca 0.8 Co 0.2 )CoSi 2 O 6 , (Ca 0.6 Co 0.4 ) CoSi 2 O 6 and (Ca 0.4 Co 0.6 )CoSi 2 O 6 was refined down to R 4σ = 2.6% by single-crystal X-ray diffraction. The crystals were synthesized at P = 3 GPa by cooling from 1500 to 1200 °C in a piston-cylinder apparatus. At the end of the refinement cycles, electron density residuals (up to 2.1 e -) were observed close to the M2 site and related to the site splitting of Ca and Co in the M2 polyhedron in the two subsites M2 and M2′. Split refinement significantly improved the agreement factor and decreased the uncertainty in the atomic coordinates. Similar features were found in (Ca,Mg)MgSi 2 O 6 and (Ca,Fe) FeSi 2 O 6 intermediate pyroxenes.The average structural changes related to the cation substitution at the M2 site in (Ca,Co)CoSi 2 O 6 , (Ca,Mg)MgSi 2 O 6 , and (Ca,Fe)FeSi 2 O 6 pyroxenes are similar: the T tetrahedron becomes more regular, the difference between M1-O bond lengths increases, and the M2-O3 bond lengths with the furthermost O3 oxygen atoms become longer. The changes in the M2-O bond distances are, however, not linear, and they are higher for more increased substitution. The largest structural deformation occurs on the (010) plane, with higher deformation at about 60° from the c axis for any composition. The orientation of the deformation ellipsoid is most related to a shift in tetrahedral chains. The scalar deformation for the cation substitution, ε s , is linearly related to the cation radius of the average M2 site (IR M2 ), i.e., the deformation is higher as the cation size decreases, following the equation: ε s = -0.0072(12)IR M2 + 0.0082(13), R 2 = 0.75. Increasing deformation with cation substitution is supported as the major limiting factor for solid solution.The displacement parameters for unsplit M2, O2, and O3 atoms increase up to the intermediate composition, indicating a local configuration for the M2 polyhedron centered by Ca and Co. However no significant change in U eq of the O3 atom is observed up to 20% substitution of the smaller cation in the M2 site. Comparison with Raman spectral data suggests that local chain structural configurations occur only for the substitution of the smaller cation in the M2 site higher than 20%, and that the substitution mechanism is different for C2/c clinopyroxenes with lower and higher Ca content.