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We report about three bismuth sulfates from mineralized quartz dikes from Alfenza (Crodo, Italy), two new phases and a rare mineral, cannonite, all growing on bismuthinite. The first new phase occurs as white, "hortensia-like" aggregates of pseudo-hexagonal platelets, with perfect basal cleavage, similar to 20 mu m wide and few micrometers thick. The approximate composition is Bi2O2(SO4), and cell parameters and symmetry, as determined by automatic diffraction tomography, are a = 22.0(4), b = 16.7(3), c = 15.9(3) angstrom, beta = 102.9(5)degrees, space group Pc or P2/c. A major stacking disorder is detected by HR-SEM images and electron diffraction data.The second new phase was detected only by TEM. It can be distinguished by its random orientation on the TEM grid (i.e., absence of preferential parting), the higher resistance under the electron beam, and different cell parameters and structure, whereas the composition is similar (Bi/S similar to 2.2/1), apart for the presence of tellurium up to similar to 6 cations percents. The unit cell is hexagonal, space group P (6) over bar 2c, a = 9.5(2) and c = 15.4(3) angstrom. In this case, a structure model was obtained ab initio from electron diffraction data. Interestingly, the mineral has a porous structure with one dimensional porosity (diameter of the channel similar to 7 angstrom).Finally, within the same centimeter sized hand-specimens, we detected also cannonite. Its identification was done by automatic diffraction tomography. The measured cell parameters are a = 7.7(2), b = 13.9(3), c = 5.7(1) angstrom, beta = 109.8(5)degrees, the space group P2(1)/c. Cannonite at Alfenza forms radiating, acicular aggregates of colorless, transparent crystals with "scalpel-like" habit, elongated along c, up to 200 mu m in length.

We use petrographic, mineralogical and geochemical data on modern river sediments of the Tupiza basin in the Bolivian Andes to investigate the relationships among human activity, heavy-metal contamination of sediments and modern erosion rates in mountain fluvial systems. Forward mixing model was used to quantify the relative contributions from each main tributary to total sediment load of the Tupiza River. The absolute sediment load was estimated by using the Pacific Southwest Inter Agency Committee model (PSIAC, 1968) after two years of geological field surveys (2009; 2010), together with data obtained from the Instituto Nacional del Agua public authority (INA, 2007), and suspended-load data from Aalto et al. (2006).Our results indicate that the sediment yield in the drainage basin is 910 ± 752 ton/km2year and the mean erosion rate is 0.40 ± 0.33 mm/year. These values compare well with erosion rates measured by Insel et al. (2010) using 10Be cosmogenic radionuclide concentrations in Bolivian river sediments. More than 40% of the Tupiza river load is produced in the upper part of the catchment, where highly tectonized and weathered rocks are exposed and coupled with sporadic land cover and intense human activity (mines). In the Rio Chilco basin strong erosion of upland valleys produce an increase of erosion (~10 mm/year) and the influx of large amounts of sediment by mass wasting processes. The main floodplain of the Tupiza catchment represents a significant storage site for the heavy metals (~657 ton/year). Fluvial sediments contain zinc, lead, vanadium, chromium, arsenic and nickel. Since the residence time of these contaminants in the alluvial plain may be more than 100 years, they may represent a potential source of pollution for human health. © 2013 Elsevier Ltd.

Canonite from Alfenza grows as crowded, radiating, acicular aggregates covering bismuthinite crystals. Individual crystals have a lozenge-shaped habit on {010}, the presumed cleavage plane of cannonite. Crystal structure refinements in the P21/c space group of two single crystals led to the following cell parameters: a = 7.7196(5) A ̊ , b = 13.8856(9), c = 5.6980(4), b = 109.174(1)o (R1 = 0.0424); and a = 7.7100(8), b = 13.8717(14), c = 5.6939(6), b = 109.155(2)o (R1 = 0.0438). Hydrogen atoms were also localized in the density-difference Fourier map and refined with soft restraints on the bond distances. Raman and IR spectroscopy confirm the presence of OH groups and the absence of molecular water, and deliver OH···O geometry wholly comparable with the structure refinement. Electron microprobe analyses revealed no significant levels of elements other than those expected in the ideal formula except fluorine which was present up to 0.14 a.p.f.u. The crystal structure can be described in terms of anion-centred OBi4 edge-sharing tetrahedra forming chains running parallel to z and strongly cemented along x by isolated SO4 tetrahedra. Each OBi4 tetrahedron is further connected along y by OH groups, making walls of composition Bi4O2(SO4)2(OH)4 parallel to (010). These walls are tied to each other along y by fewer Bi–O–S bridges and weaker OH···O bonds.

In recent years, many efforts have been made on the synthesis of new self-assembled materials, and on scientific understanding of the formation mechanism from building molecules. With the aim to develop new functional materials, layered inorganic compounds recently attracted considerable interests for the preparation of nanoscale organic/inorganic hybrids. A large class of minerals presents inherently nanostructured morphologies. Within this group, we cite, to name a few, chrysotile, crocidolite, and montmorillonite, being examples of crystalline aggregates of nanotubes, nanorods, and nanosheets, respectively. On this basis, synthetic “geo-inspired” materials are being developed, with the aim to enhance their possibility to be employed as nanomaterials in technological applications. On the other hand, the surface of such minerals is rich of chemical groups which can bind covalently or electrostatically organic compounds capable to confer technological functionalities to the ultimate hybrid system. In order for a transition from bare mineral to functional material to be achieved, the development of processes for the deposition of highly-oriented thin film phases of such mineral nanoparticles are mandatory. Indeed, their marked anisotropic morphology influences also their physical properties, which may vary to a great extent depending on the probed direction. Here, we show the results of a scanning probe and electron microscopy, X-ray diffraction, and IR optical analysis of nanostructured thin films of natural and synthetic minerals obtained by liquid phase deposition of colloidal solutions. By assisting the deposition process with a static magnetic field, we demonstrate the possibility to induce a preferential orientation of the deposited nanoparticles, thanks to the anisotropy of their diamagnetic or paramagnetic susceptibilities. This effect is also studied in minerals deliberately doped with paramagnetic species such as Fe(II) and Fe(III) ions. Hybrid inorganic-or

Nine black powders found in Pompeii houses in three different types of bronze vessels (cylindrical theca atramentaria, unguentaries, and aryballoi) were characterized in order to assess a correspondence between the composition and the type of vessel and, possibly, to verify if these powders were inks or not. For the compositional characterization, a multi-analytical approach was adopted, which involved the use of scanning electron microscopy-energy dispersive X-ray, Fourier-transformed infrared spectroscopy, Raman, X-ray diffraction, electron paramagnetic resonance spectroscopy, thermogravimetric analysis, gas chromatography coupled with mass spectrometry (GC/MS), and pyrolysis GC/MS. Powders contained in cylindrical theca atramentaria form a homogeneous group, and their organic and inorganic compositions suggest that they were writing inks, while powders contained in unguentaries and aryballoi could have had several different uses, including writing inks and cosmetics. Furthermore, the composition profile of the powders found in cylindrical cases shows that, at 79 AD: , in Pompeii, carbon-based inks were still used for writing, and iron gall inks had not been introduced yet

Mesoporous Cr or Pt-doped WO3 thin films to be employed as ammonia gas sensors were prepared by a fast one-step sol–gel procedure, based on the use of triblock copolymer as templating agent. The obtained films were constituted by aggregates of interconnected WO3 nanocrystals (20–50 nm) separated by mesopores with dimensions ranging between 2 and 15 nm. The doping metals, Pt and Cr, resulted differently hosted in the WO3 mesoporous matrix. Chromium is homogeneously dispersed in the oxide matrix, mainly as Cr(III) and Cr(V) centers, as revealed by EPR spectroscopy; instead platinum segregated as Pt (0) nanoparticles (4 nm) mainly included inside the WO3 nanocrystals. The semiconductor layers containing Pt nanoclusters revealed, upon exposure to NH3, remarkable electrical responses, much higher than Cr-doped and undoped layers, particularly at low ammonia concentration (6.2 ppm). This behavior was attributed to the presence of Pt nanoparticles segregated inside the semiconductor matrix, which act as catalysts of the N–H bond cleavage, decreasing the activation barrier in the ammonia dissociation. The role of the mesoporous structure in influencing the chemisorption and the gas diffusion in the WO3 matrix appeared less decisive than the electronic differences between the two examined doping metals. The overall results suggest that a careful combination between mesoporous architecture and metal doping can really promote the electrical response of WO3 toward ammonia. Keywords Pt and Cr—doped WO3 Mesoporous thin film Gas sensors Morphological, electronic and electrical