Motivation for detecting engineered nanoparticles (ENPs) in the environment comes from a need to understand fate and behavior of these materials in natural matrices. The difficulty lies in the low expected ENP particle number concentration (PNC) and the presence of a large and variable background concentration of natural NPs. We report the PNCs and characteristics of cerium-bearing nanoparticles (Ce-NPs) and titanium-bearing nanoparticles (Ti-NPs) in an aquatic matrix (the Seine River and three of its tributaries) with the use of single particle ICP-MS (spICPMS) and electron microscopy (FEG-SEM). Ce-bearing and Ti-bearing particles were observed in suspended particulate matter collected onto 0.2 μm and 1 kDa filters, using FEG-SEM imaging. At Marnay-sur-Seine, the upstream point, PNCs for Ce-NPs and Ti-NPs were 0.47 ± 0.07 × 106 and 1.35 ± 0.17 × 106 particles as measured by spICPMS. The maximum PNC for both Ce-NPs and Ti-NPs, 1.59 ± 0.10 × 106 particles mL−1 and 5.89 ± 0.10 × 106 particles mL−1, respectively, were found in the Marne River, a major tributary to the Seine. It was shown that downstream of each confluence, an increase in the PNC of the Seine is observed, suggesting a significant contribution of the different tributaries. Mass balance of particles flows and elemental ratios of Ce/La showed that in the Marne and the Oise River, a contribution of natural CeO2 NPs exists. The anthropogenic contribution in TiO2 ENPs for the Marne River was further assessed with Ti/Al, Ti/V, and Ti/Y elemental ratios. Near constant element ratios in the Seine below the Orge River and Paris city suggest neither contribute significantly to Ce or Ti NP concentrations. The study provides further investigation of the strengths and limitations of the application of spICPMS to natural samples and contributes data to the currently highly-limited dataset on natural NP backgrounds in rivers, information that is key to assessing the potential for quantifying the input of ENPs to surface waters. Of the total mass of Ce and Ti, 83 and 90%, respectively, could be detected as particles by spICPMS.

Several years after decommissioning, a magnesium dross and mixed waste heap at a former industrial facility is still reactive, as evidenced by the emission of heat, Volatile Organic Carbon (VOCs), acetylene (C2H2), cyanide (HCN) and ammonia (NH3) from deep, discordant, epigenetic fissures. To evaluate the longer-term stability of the waste heap material, four cores were collected to evaluate vertical variations in temperature, moisture, gas composition, geochemistry, and mineralogy. Temperature increased with depth and peaked at around 8 m, reaching in excess of 90 °C. The waste heap was a mixture of unreacted materials (mainly MgO and CaO) and a variety of hydrated secondary reaction products. Formation of the latter could account for the generation of heat and creation of the fissures via thermal and secondary mineral volumetric expansion. With a large inventory of unreacted CaO and MgO and substantial in situ water present, the waste heap will probably remain reactive in the foreseeable future. Importantly, the CaO/MgO ratio of solid materials in the waste heap provides a useful proxy for down hole temperature, pH, and fugitive gas concentrations. Fugitive gases emitted by the waste heap are related to the reaction of co-existing minerals in the heap based on an historical analysis of site waste disposal. These waste materials include calcium carbide (CaC2), magnesium nitride (Mg3N2) and calcium cyanamide (CaCN2). Capping to limit the ingress of additional meteoric water and targeted venting to facilitate cooling and the controlled release and dispersion of gases are recommended to manage the environmental risk.

Asbestos refers to silicate minerals belonging to the serpentine group (chrysotile) and the amphibole group (crocidolite, amosite, tremolite-asbestos, anthophyllite-asbestos and actinolite-asbestos). Such materials have strong effect on health, and real-time instrumentation is on demand to detect asbestos. The current real-time techniques use only some aspects of the optical properties of asbestos, since the scattering properties (brightness and linear polarization scattering functions) of the various natures of asbestos has not been yet fully determined. We present here the brightness and linear polarization scattering functions for 6 natures of asbestos in the 425-1650 nm spectral domain obtained with the PROGRA2 instrument. Although the samples exhibit different shapes, the linear polarization values remain low, bell-shaped as usual for irregular particles, and close to those of mineral particles previously studied with PROGRA2. On the opposite, asbestos brightness curves present strong differences for the different samples. The chrysotile is darker than the other samples in the 80 degrees-150 degrees angle range, probably due to its tubular shape that can act as a light trap for scattering angles greater than a few tens of degrees. Other asbestos particles can be distinguished from building materials such as glass wool or plaster through their brightness curves in some scattering angle ranges. These new laboratory measurements indicate that the optical scattered properties could be used in the future to tentatively detect asbestos particles in a medium generated from building materials. (C) 2020 Elsevier Ltd. All rights reserved.

The need to quantify engineered nanoparticles (ENPs) in the environment is due to the increasing incorporation of these particles in the daily products, which threatens human health and can possibly impact natural systems. Ceria NPs (CeO2NPs) and titanium dioxide NPs (TiO2NPs) are two of the most used ENPs in the world. In this study their occurrence was determined in river waters with accurate and relevant techniques such as single particle ICP-MS (spICPMS). In the Loire River (France), the variation of both CeO2NPs and TiO2NPs could be assessed locally, with an increase of the concentrations near a wastewater treatment plant (WWTP) outlet as well as in a lake connected to the river and dedicated to outdoor activities. In the upstream river water, supposedly less impacted by NPs, 6.4 ± 1.2 × 104 part mL–1 Ce-bearing and 13.4 ± 1.8 × 104 part mL–1 Ti-bearing particles were measured. These values increased to 33.9 ± 3.4 × 104 part mL–1 Ce-bearing and 80.3 ± 3.4 × 104 part mL–1 Ti-bearing particles near the WWTP outlet. Equivalent size for sphere distributions ranged from 24 nm to 70 nm for CeO2 and from 80 nm to 500 nm for TiO2 in the river water. In the lake, a raise of the concentrations has been observed with 38.3 ± 2.0 × 104 part mL–1 and 71.6 ± 2.1 × 104 part mL–1 containing Ce and Ti, respectively, with similar size distributions. FEG-SEM imaging confirms the occurrence of Ce- and Ti-bearing particles in the water samples. On the contrary, NPs seem to undergo strong heteroaggregation in the Loire river water. The Ce/La elemental ratios does not evolve from upstream to downstream the WWTP outlet, suggesting that a natural origin cannot be excluded to explain the increase observed in NPs number concentration. On the contrary, the Ce/La ratio increases in the outdoor activities center, which suggests the contribution of NPs potentially related to the cars parked nearby. Besides, elemental ratios Ti/V and Ti/Y have been assessed to highlight an anthropogenic source of Ti in both sampling sites, possibly to the sunscreens used during the summer.

Sheet nacre is a hybrid biocomposite with a multiscale structure, including nanograins of CaCO3 and two organic matrices [1] : (i) the interlamellar, mainly composed of β-chitin and proteins, and (ii) the intracrystalline composed by silkfribroin like proteins. This material is currently studied for the manufacture of small prostheses – eg. rachis or dorsal vertebra prostheses [2] – which can be subjected to slip or fretting motion at the nanoscale. In a recent work, it has been demonstrated that the tribological behavior of sheet nacre is completely controlled by the organic matrices on a large range of frictional dissipated powers. Besides, various dissipative mechanisms are involved within the contact as function of the injected power. Thus, an interesting lubricant effect [3] due to the presence of an organic tribolayer generated by the organic interlamellar phase can be observed in association with some very long recovery-time viscoelastic deformations of the organomineral tablets [1, 3]. However, the influence of these organic matrices on the frictional behavior is not completely

In order to develop a mineralogical and chemical database, which will be associated with an on-line-on mine instrument, for nickel mining exploration, several garnierite samples were studied in laboratory. The collected samples are Ni-bearing laterites from New Caledonia and Dominican Republic and are mainly composed of serpentine-like and/or talc-like and/or sepiolite-like phase. These three types of phases are clearly differentiated by X-ray diffractometry (XRD). The presence of Ni within the crystallographic structure of these phases can be observed from the infrared or Raman spectra, where the effect of Mg/Ni substitutions causes shifts in some bands. The relative intensity of these bands can be correlated with the Ni content. These different parameters are a reliable indicator to define the nature of garnierite and to have an indication on the Ni content.

(1) Eramet IDEAS, Eramet Group, France, Trappes, France (thanh.bui@erametgroup.com), (2) ThermoFisher Scientific (TFS), Artenay, France, (3) Catura Geoprojects, Paris, France, (4) GEOPS-Université Paris Sud-Paris Saclay, Orsay, France (beate.orberger@u-psud.fr), (5) L2S, CNRS, Centrale Supélec, Université Paris-Saclay, France, (6) BRGM, Orléans, France, (7) CRISMAT-CNRS, Normandie Université, Caen, France; , (8) Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, The Netherlands, (9) Eramet Nickel Division, Eramet Group, Trappes, France

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Detection and Identification of Asbestos in Aerosols by LIBS in a Low Temperature Plasma Cédric Duée, Marie Hénault, Thomas Lecas, Laifa Boufendi, Henry Pillière, Xavier Bourrat

Asbestos consists in natural minerals crystallized in a specific habit and possessing in particular properties. In the case of Naturally Occurring Asbestos, usual methods applied to the identification of mineral fibers and the determination of their possible asbestiform nature seems not efficient, especially in the case of mineral fibers included in mineral matrix. We present a new in-situ method based on the use of confocal Raman-in-SEM imaging implemented in a Scanning Electron Microscope as an efficient method for in-situ mineralogy. The limitation of conventional methods is discussed. We applied 2D-Raman imaging to the identification of sub-micrometric fibers included in different mineral matrix. We were able to identify actinolite fibers down to 400 nm in diameter, included in feldspar, quartz and/or calcite matrix. Moreover, Confocal Raman allows the collection of 3D data that would provide access to critical information on the morphology of the amphibole fibers in the volume, such as aspect ratio, fibers distribution and amphibole volume fraction. We performed this method on various examples of rocks containing actinolite fibers of mean structural formula is: Na-0,Na-04-0,Na-12 Mg-2,Mg-79-3,Mg-73 Al-0,Al-29-0,Al-58 K-0,K-01 Ca-1,Ca-79-1,Ca-98 Mn-0,Mn-01-0,Mn-09 Fe2+(0,99-1,91) Fe3+Si-7,Si-64-7,Si-73 O-22(OH)(2). We demonstrated that coupling confocal Raman imaging and SEM is a new and efficient in-situ method for identification and morphological characterization of amphibole fibers.

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The objective of the SOLSA project (EU-H2020) is to develop an analytical expert system for on-line-on-mine-real-time mineralogical and geochemical analyses on sonic drill cores. As one aspect of the system, this paper presents the building of the hyperspectral library and its incorporation into sparse unmixing techniques for mineral identification. Twenty seven spectra representing 14 minerals have been collected for the library. Three sparse unmixing techniques have been investigated and evaluated using simulated data generated from our hyperspectral library, and real hyperspectral data acquired from a serpentinized harzburgite sample. Among the three techniques, the collaborative sparse unmixing by variable splitting and augmented Lagrangian (CLSUnSAL) method provided the best accurate results on the simulated data. In addition, the results of the CLSUnSAL method show high correlation with that of the QEMSCAN® analysis on the harzburgite hyperspectral data.

Sheet nacre is a hybrid biocomposite with a multiscale structure, including nanograins of CaCO3 (97% wt% - 40 nm in size) and two organic matrices: (i) the interlamellar mainly composed of beta-chitin and proteins, and (ii) the intracrystalline composed by silk-fibroin-like proteins. This material is currently contemplated for the manufacture of small prostheses (e.g., rachis and dorsal vertebra prostheses) which are subjected to micro-slip or fretting motion. In this work, the tribological behavior of nacre is studied by varying the frictional dissipated power from few nW to several hundred mW, in order to assess the various responses of the different nacre's components, independently. Results reveal various dissipative mechanisms vs. dissipated frictional power: organic thin film lubrication, tablet's elastoplastic deformations, stick-slip phenomenon and/or multiscale wear processes, including various thermo-mechanical processes (i.e., mineral phase transformation, organics melting and friction-induced nanoshocks process on a large range). All these mechanisms are controlled by the multiscale and anisotropy of its structure - and especially by its both matrices and respective orientation vs. the sliding direction.

On-line-real-time combined mineralogical and chemical analyses on drill cores are highly demanded by mining and metallurgical companies to speed up exploration and mining, as they provide more precise geomodels, and optimal definition of metallurgical parameters. The EU-H2020 SOLSA project (www.solsa-mining.eu), targets to construct an expert system coupling sonic drilling with an on-linereal-time analytical system combining systematic mineralogical and chemical analyses on drill cores. The analytical system comprises a profilometer, a high resolution RGB camera, VNIR (Visible Near Infrared)/SWIR (Shortwave Infrared) (Specim Ltd., Finland) hyperspectral cameras, and a XRF spectrometer. The objective is to reach real-time decision making through scanning of about 60 m drill cores per day. The system will be validated for nickel laterites, which represent 70 % of the Ni resources worldwide. SOLSA will provide open databases for combined analyses. Therefore, a hyperspectral open data base is built for nickel-laterite specific rocks and pure mineral samples. All these samples are also analyzed by conventional laboratory methods (XRD, Raman spectroscopy, SEM, EPMA and QEMSCAN ® ). Currently, 27 spectra representing 14 minerals (i.e., asbolane, chromite, diaspore, olivine (forsterite), clay minerals (kaolinite, saponite, pimelite), magnesite, pyroxene (enstatite), serpentine (lizardite, nepouite, antigorite), talc, calcite) have been collected for our hyperspectral library. We plan to open it to public at https://solsa.crystallography.net/sod/. As the spectra of drill cores often contain a mixture of minerals, spectral unmixing techniques have been investigated and implemented. We employed sparse unmixing techniques, which have connections with the statistical and geometrical frameworks and have recently been demonstrated a great success in unmixing hyperspectral data for remote sensing applications. Sparse unmixing techniques aim at finding the optimal subset of signatures in a spectral library that can best model each mixed pixel. The methods exploit the fact that a spectrum always contains a mixture of a small numbers of endmembers, which is the case in our data acquired from the nickel-laterite samples. Among investigated unmixing methods, the collaborative sparse unmixing by variable splitting and augmented Lagrangian (CLSUnSAL) method provided the most accurate unmixing results on simulated data that were generated from our hyperspectral library. Hyperspectral data acquired from a serpentinized harzburgite sample (SOLSA label of ER-MB00-0012) on a polished surface, were processed by the CLSUnSAL method using our hyperspectral library. The same sample was analyzed by QEMSCAN ® . A good correlation was found for the mineralogy and mineral distribution (olivine, pyroxene, serpentine, chromite) between the results of the CLSUnSAL and QEMSCAN ® methods. These analyses will be cross-evaluated by the Raman spectroscopy mapping.

On-line, real-time chemical and mineralogical analyses on drill cores are highly demanded by mining companies. However, they are a challenge because of drill core surface state and sample heterogeneities. We selected four rock samples: highly porous, siliceous breccia and serpentinized harzburgite coming from the base of a nickel laterite profile in New Caledonia which were sonic drilled, and fine grained, homogeneous sandstone and coarse grained granite which were diamond drilled and provided by Eijkelkamp Sonic Drill with unknown origin. The samples were analysed at five surface states (diamond or sonic drilled, cut as squares, polished at 6 and 0.25 mu m, powdered < 80 mu m) by portable XRF spectroscopy (pXRF) in mining and soil modes and portable infrared spectroscopy (pIR, Visible and Near Infrared-Short Wave Infrared range (VNIR-SWIR)). A total of 52 pXRF and 200 pIR analyses were performed per sample at each surface state. This study shows that the surface state has minor influence on the results of the portable instruments. By comparing pIR and pXRF results with laboratory devices (Raman spectroscopy, XRD with Rietveld refinement, XRF spectroscopy and ICP-AES), we evidence the lower and less accurate information obtained from handheld instruments in terms of chemistry and mineralogy. The porosity and grain size effect on the measurement need to be taken into consideration for on-line drill core analyses. We show that the combination of complementary analytical techniques helps to overcome the drawbacks of the core texture and of the precision of portable instruments in order to define the regions of interest (ROI) for mining companies. We also demonstrate that a precise pXRF calibration is mandatory and that the concentration of light elements (Si, Mg), even if not accurate, shows sufficient contrast along the lateritic profile for ROI definition.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. PLASMIANTE: A plasma filter for the detection of airborne asbestos. Cédric Duée, Marie Hénault, Thomas Lecas, Laifa Boufendi, Xavier Bourrat, Hubert Haas, Henry Pillière

Formation of nacre (mother-of-pearl) is a biomineralization process of fundamental scientific as well as industrial importance. However, the dynamics of the formation process is still not understood. Here, we use scanning electron microscopy and high spatial resolution ion microprobe depth-profiling to image the full three-dimensional distribution of organic materials around individual tablets in the top-most layer of forming nacre in bivalves. Nacre formation proceeds by lateral, symmetric growth of individual tablets mediated by a growthring rich in organics, in which aragonite crystallizes from amorphous precursors. The pivotal role in nacre formation played by the growth-ring structure documented in this study adds further complexity to a highly dynamical biomineralization process.

Within the framework of responsible mining, a SOLSA project (www.solsa-mining.eu) to develop an in-situ tool allowing a quick mineralogical identification of site drill cores has been recently launched. Its objective is to develop new or improved highly-efficient and cost-effective, sustainable exploration technologies. It combines and integrates non-destructive sensors: X-ray fluorescence, X-ray diffraction, infra-red and Raman spectroscopy and 3D imaging. The challenge is to address mixtures of hard and soft rocks, as encountered in a lateritic environment. This paper focuses on the determination of spectral characteristics of laterite drill-cores in the visible to short wave infrared spectral range. One of the most important prerequisites is to study the influence of the surface roughness effect on infra-red spectroscopy analyses. For this purpose, four different rock samples: breccia, sandstones, granite and peridotite, each at five surface states have been considered: as-drilled, as-sawn, polished at 6 μm, polished at 0.25 μm and crushed to powder. The reflectance spectra have been acquired with an ASD Fieldspec 3® spectroradiometer with a contact probe at a sampling surface of 1.76 cm 2 , allowing a spectral analysis at wavelengths from 350 up to 2500 nm. The powder spectrum of breccia presents a higher reflectance than the four other spectra from the same material but weak absorption features. The as-sawn sample presents the higher absorption depth, followed by as-drilled sample and the two polished samples (figure 1). At wavelength 2219 nanometers, a peak of absorption is present. The presence of clay minerals is assumed like illite/sericite with more or less smectite, due to the relatively deep water absorption around wavelength 1900 nanometers.

In order to evaluate the instrumental parameters for the combined on-line-on-mine-real-time expert system SOLSA (http://www.solsa-mining.eu), portable and laboratory analyses were carried out on coarse granite, sandstone, serpentinized harzburgite and siliceous breccia. Each sample was studied at 5 different surface roughnesses (sonic or diamond drilled, cut, polished at 6 mu m and 0.25 mu m, sample powders). X-ray diffraction (XRD), portable Infra-Red (pIR) and X-ray-fluorescence (pXRF), and laboratory micro-Raman spectroscopy gave complementary and corroborating results. No major effect on the analyses was noted for the selected surface states. pXRF gave variable results except for the homogeneously serpentinized harzburgite, related to coarse or contrasting grain sizes or pores, small spot size (3 mm) and needs close-to-surface analyses. Portable IR (spot size 1.76 cm(2)) is carried out close to surfaces while Raman spectroscopy (1-2 mu m) is performed at distance. Sampling strategies have to be defined for each lithology. Major challenges for a combined on-line analysis are to adapt the specificities of the techniques to (1) analyse similar surface areas (from 2 cm(2) (pIR) to < mu m (Raman)), (2) smartly combine all the techniques into a single instrument, and (3) develop appropriate databases to reach a reliable "real-time" outcome results, which can be used for more precise geomodeling, and to rapidly define exploration and beneficiation parameters.

Pearls are greatly valued by the jewelry industry as shiny organic gems. Their glossiness, results of a defense mechanism against foreign particles. Pearls (Hyriopsis cumingii) are produced from a natural biomineralization process controlled by organic molecules. Pearl biocrystal is a hybrid composite: organic / mineral (3 % / 97 %). The regular form of pearl mineralization is aragonite, an orthorhombic polymorph of calcium carbonate. Each biocarbonate plateletis a polygranular composite of aragonite nanograinsstuck by proteins. It diffracts as a single crystal and is so called mesocrystal. Platelets have a polygonal shape, few hundreds of nanometersthick, whichstack along the c-axis with chitin organic 'cement'. This layered structure produces the well-known 'pearly' aspect. Sometimes, pearls show a biomineralization defect characterized by a lack of shine (also called 'milky pearl'). It has been established that this defect is related to the change in crystallization form: from orthorhombic aragonite to hexagonal vaterite [1]. Fig. 1: SEM observation of the interface: same area as seen with cathodoluminescence (CL, left) and in secondary electron mode (SE, right)