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This work relates to the occurrence and crystal-chemical characterization of fibrous erionite, a carcinogenic zeolite, discovered for the first time in the volcanic rocks of Latium, Italy. The erionite samples were investigated using SEM, TGA, PXRD, FTIR and Raman spectroscopies. Cell parameters, fractional coordinates and site scattering were refined using the Rietveld method. Two different types of erionite were found, having different crystal morphologies, chemical composition, and structure. The first type is an extremely fibrous erionite-K, with Si/(Si+Al) ratio of 0.77, cell parameters a=13.255 Å, c=15.053 Å and cell volume V=2290.49 Å3. The second type is acicular to highly fibrous erionite-Na, with a lower Si/(Si+Al) ratio (0.72-0.73) and larger cell parameters (a=13.291 Å, c=15.146 Å, cell volume V=2317.35 Å3). Both erionite types occur as fibers of inhalable size. The structure of both samples, refined by the Rietveld method on powder X-ray diffraction data, collected in transmission mode on capillaries, is consistent with that of samples with similar extra-framework cations content. Raman and FTIR data are presented and discussed. The described finding of potentially carcinogenic erionite in the volcanic rocks of Latium that are typically rich in zeolites of various nature, both as cavity filling and devitrification products of glass, suggests that this hazardous mineral might be more common than previously believed in the area and points to the need for detailed and more systematic studies., Periodico di Mineralogia, Vol. 92 No. 2 (2023)

This opening paper introduces the contributions of this special issue on mineral fibres and reports a gallery of the major results accomplished within the multidisciplinary project PRIN (PROGETTI DI RICERCA DI RILEVANTE INTERESSE NAZIONALE) 2017 “FIBRES: a multidisciplinary mineralogical, crystal-chemical and biological project to amend the paradigm of toxicity and cancerogenicity of mineral fibres” by the six different Research Units from the Universities of Ancona, Genova, Modena, Rome, Pisa-Parma, and Urbino. The main goal of the project was to increase the knowledge of the mechanisms by which mineral fibres, with special attention to asbestos and fibrous erionite, prompt adverse effects in vivo, linking the fibres’ crystal-chemical-physical parameters to their toxicity/carcinogenicity potential and recasting the existing mechanistic ‘fibre toxicity paradigms’. This special issue contains specific contributions from each Research Unit of the project. The implications of the findings of the project are beyond the advance of the knowledge in the world of mineralogy/crystallography and constitute a remarkable progress in the understanding of the biological activity of mineral fibres in vivo., Periodico di Mineralogia, Vol. 92 No. 2 (2023)

International audience; Tremolite is one of the most common amphibole species and, in the fibrous form (i.e., characterized by crystals/particles consisting of fibres with length > 5 µm, width 3), one of the six asbestos minerals. Until now the attention of crystallographers has focused only on samples from continental environment. Here we report the first chemical and structural data of a tremolite asbestos found along the Mid Atlantic Ridge (MAR) at the eastern intersection of the Romanche Transform Fault (Equatorial MAR). Tremolite is associated with chlorite and lizardite and was formed through the green shale facies lower than zeolite in a predominantly fluid system. MAR tremolite asbestos shows very slight deviations from the ideal crystal structure of tremolite. Differences in cation site partitioning were found with respect to tremolite asbestos from ophiolitic complexes, attributed to the different chemical–physical conditions during the mineral formation. In particular, oceanic tremolite asbestos is enriched in Al and Na, forming a trend clearly distinct from the continental tremolites.

The properties of rocks are determined from the physical properties of minerals composing the rock, which in turn ultimately depend on the crystal phonon modes and electron density of states. Amphiboles (AB2C5T8O22W2, C5 = M12M22M3) are among the major hydrous-silicate mineral constituents of the lithosphere, whose structure consists of strips of 6-membered TO4-rings attached to MO6 octahedra. To elucidate the atomistic origin of the rock conductivity observed in peculiar geological settings, we have studied single crystals of MFe-containing amphiboles from different subgroups by in situ high-temperature polarized Raman spectroscopy and density-functional-theory calculations of the electron band structure of grunerite (A¨Fe2+2Fe2+5Si8O22(OH)2) as a model pure-MFe2+ amphibole [1]. Above a certain temperature resonance Raman scattering occurs, due to the formation of small polarons arising from the coupling between polar optical phonons and electron transitions within Fe2+O6 octahedra, the mobility of which through the mineral bulk is strongly anisotropic. The FeO6-related polarons coexist with delocalized H+, that is, at elevated temperatures typical of lithosphere Fe-bearing amphiboles are conductive and exhibiting two types of charge carriers: electronic polarons and H+ cations, regardless of the oxygen fugacity. However, the presence of external oxygen favours the ejection of H+ and electrons from the crystal. Therefore, at lithospheric temperatures Fe2+-bearing amphiboles can be in a unique metastable state with an anisotropic surface-to-bulk gradient in the chemical potential. Same phenomena are expected for other rock-forming minerals sharing a similar structural feature with amphiboles: linked TO4-rings and MO6-octahedra. [1] Mihailova et al. Commun. Mater. 2, 57/1-10 (2021)

This is the accepted manuscript of the paper "Microlitter pollution in coastal sediments of the northern Tyrrhenian Sea, Italy: microplastics and fly-ash occurrence and distribution", published as final paper in "Estuarine, Coastal and Shelf Science 241 (2020) 106819 https://doi.org/10.1016/j.ecss.2020.106819 Marine litter is included in the eleven descriptors of the Marine Strategy Framework Directive (MSFD) necessary for the assessment of the marine environmental status. In this work, we studied the abundance and typology of microparticles extracted from coastal sediments in the northern Latium area, Tyrrhenian sea, Italy. Particles having different shapes (fragments, microspheres, and filaments), size and color were recognized to belong to two typologies, i.e. microplastics (MPs) and aluminum silicate microspheres (ASMs) interpreted as fly-ash produced by fossil fuel combustion. MPs abundances were comparable with data from the literature related to the same depositional contexts in the Mediterranean Sea and elsewhere, while ASMs contributed 32% to the total average microlitter abundance in this coastal area. MPs and ASMs distribution could reflect the contributions of the land-based sources and the hydrodynamic features of the study area.

Opals and cryptocrystalline silica may be found in a very broad range of geological environments (Chauviré et al., 2017), systematically related to the availability of an aqueous fluid. Due to its conditions of formations, opal may contain abundant H2O, CO2 or both (Sodo et al., 2017), and the presence of these molecules may provide information of their genetic context. In this work we studied a series of samples from the volcanic region of Allumiere-Tolfa, north of Rome (Latium, Italy). This district has a Pliocene-Pleistocene age and is related to the Tuscan acid volcanism. It shows a very intense late-stage hydrothermal alteration that gave rise to two distinct ore basins: one to the south of the Allumiere town, consisting of sulfide (Pb, Fe, Zn, Hg) and Fe-oxide mineralizations, and a second, to the north, mainly consisting of alunite and kaolin. Both ore deposits were intensely exploited during the medieval to recent period. The hydrothermal alteration giving rise to the sulfate and clay deposits is also associated with a pervasive deposition, within the early volcanics, of opaline or microcrystalline silica, consisting of mineral replacements, veins and formation of agate druses. Although the sulphide-sulfate and clay products have been studied, due to their interest as georesources, and relevant petrological, geochemical and isotopic data can be found in the oldest literature (Lombardi and Sheppard, 1977), the silica mineralizations have never been addressed. We studied here a series of samples occurring as vein depositions or as banded crystallizations from different areas in the volcanic district. The samples were examined by using a combination of XRD, SEM-EDS and FTIR + Raman imaging. Opaline silica with different degree of order, from opal AN (hyalite) to opal A to opal CT, was identified. Some samples contain CO2 besides H2O/OH. The banded agates were found to consist of a layering of micro-crystalline and fibrous quartz (chalcedony) with different water contents, interbedded with moganite-rich layers; moganite, in particular was found to be associated to lower H2O contents. The 18O and D/H isotopic data of Lombardi and Sheppard (1977) indicate temperatures around 120-100°C for the hydrothermal process responsible for the hydrothermal deposits, in close agreement with the typical range of T for the formation of opaline silica (Heaney, 1993). The ore forming process can be thus interpreted following the classical model of hydrothermal/metasomatic phenomena at low-depth, accompanied by extensive alteration of the pre-existing rocks, due to mixed magmatic/meteoric fluids, with the formation of kaolinite + alunite + sulfates + silica (Hedenquist et al., 2000). ReferencesChauviré, B., Rondeau, B., Mangold, N. (2017) Eur. J. Miner. 29, 409-421Heaney, P.J. (1993) Contrib. Mineral. Petrol., 115, 66-74.Hedenquist, J.W., Arribas, A.R., Gonzalez-Urien, E. (2000) SEG Reviews, 13, 245-277.Lombardi, G. and Sheppard, S.M.F., (1977) Clay Miner., 12, 147-161.Sodo, A., Casanova Municchia, A., Barucca, S., Bellatreccia, F., Della Ventura, G., Butini, F., Ricci M.A. (2016) J. Raman Spec. 47, 1444-1451.

kircherite (IMA 2009-084), a new member of the cancrinitesodalite group of minerals from Valle Biachella, Sacrofano, (Rome), in the Sabatini volcanic complex, Latium, Italy. The mineral occurs within miarolitic cavities of holocrystalline, syenitic, volcanic ejecta, associated with sodalite, biotite, iron oxides, titanite, fluorite, and a pyrochlore group mineral. The groundmass of the ejecta consists essentially of potasiumfeldspar, with minor sodalite and brown mica. Kircherite occurs typically as parallel associations of hexagonal, thin, tabular crystals (2 or 3 mm in diameter and 1 mm in thickness). Single platelets have a thickness that very rarely exceeds 0.5 mm. Crystals are colourless to light gray to white, translucent to opaque in the most altered parts of the crystals; lustre is greasy to silky. Fluorescence is in light pink under LW UV and deep red under SW UV. Hardness is (Mohs): 5.5; micro-indentation VHN load 10 g, mean 648.4 kg mm-2, range ± 208.9 kg mm-2. Cleavage on {001} is good. Density (calc.) is 2.457 g cm-3. Kircherite is non-pleochroic and uniaxial negative with ω = 1.510(2), ε = 1.502(2). Kircherite is trigonal, space group R32, with , a = 12.8770(7) Å, c = 95.224(6) Å, V = 13677.2(13) Å3, Z = 1. The empirical chemical formula obtained from EMP analyses is: (Na89.09Ca31.63K18.85Fe0.20Mn0.06Mg0.05Ti0.03)Σ=139.91 (Si108.13 Al107.87)Σ=216.00O430.08(SO4)32.59 Cl2.00F0.53(CO3)0.09·6.86H2O, which corresponds to the ideal formula [Na90Ca36K18]Σ=144 (Si108Al108O432)(SO4)36·6H2O. The strongest six reflections in the X-ray powder pattern are [d in Å (I %) (hkl)]: 3.72 (100) (300), 2.65 (100) (2.1.28; 0.0.36), 3.23 (65) (2.1.19), 3.58 (60) (1.2.14), 3.60 (53) (1.0.25), 3.80 (52) (1.2.11). The single-crystal FTIR spectrum rules out OH groups and shows the presence of H2O and CO2 molecules in the structural cages of the mineral. The structure can be described as a stacking sequence of 36 layers of six-membered rings of tetrahedra along the c axis as ACABCABCABCACBCABCABCABCBABCABCABCAB…, where A, B and C represent the positions of the rings within the layers. The structure has 6 cancrinite cagϵe)s, 2(4 sodalite cages (S) and 6 LOSOD cages (L) within the unit cell, and these account for a maximum of 36 SO4 2- groups and 6 H2O molecules (or Cl anions). There is a unique sequence of cages, ϵSSSLSSLSSSϵ and adjacent sequences are shifted 1/3 along [001]. Kircherite, having 36 layers, is the cancrinite with the longest complex sequence described to date. The name is for Athanasius Kircher (1602–1680), a German Jesuit who was the founder of the museum of the Collegium Romanum in 1651, hereafter named the Museum Kircherianum.

Il progetto SMART ENVIRONMENTS, svoltosi negli anni dal 2015 al 2017 presso l’Ateneo Roma Tre, è stato finanziato dalla Regione Lazio con lo scopo di sostenere l’attività di ricerca orientata all’accrescimento della competitività tecnologica del tessuto imprenditoriale della regione e di promuovere il sistema della ricerca e innovazione mediante la valorizzazione delle infrastrutture di ricerca presenti sul territorio. Un indirizzo che aveva, fin da subito, individuato nel trasferimento tecnologico una delle chiavi in grado di sostenere lo sviluppo industriale della Regione Lazio in un periodo difficile dove però la possibile ripresa economica garantiva disponibilità di investimenti. SMART ENVIRONMENTS, con la sua dichiarata progettualità a forte vocazione imprenditoriale, è andato a esplorare, quindi, il nuovo terreno della Terza Missione delle Università, dove il rapporto con il territorio finisce al centro dell’operare accademico non più in una ottica di diffusione del sapere che procede dall’alto verso il basso ma con la pretesa di lavorare insieme al tessuto produttivo, sia esso industriale, di servizio o culturale, per coadiuvare le imprese nel difficile compito di rinnovamento tecnologico e di idee rimanendo al contempo fecondati dalle esigenze sociali e di mercato.

In this work we report on a complete crystal-chemical characterization of a near end-member riebeckite from Malawi, and use the available data to critically compare information obtained from different analytical methods. The sample occurs as well-formed and very large single crystals in pegmatitic rocks. Accurate site-populations were determined by combining single-crystal structure refmement and electron microprobe analysis (EMPA). The Fe3+ /Fe2+ ratio was obtained from Mossbauer spectroscopy. Lithium was quantified by Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS).

In the archaeological Khmer complex (Cambodia), an unusual black patina covering both the exterior and interior walls of the Neang Khmau temple, has been observed during a recent conservative survey. In fact, it is present over all the four facades of the temple, covers a relevant part of the vertical surfaces protected from rainfall and is also homogeneously distributed on the interior of the monument. The upper and the lower areas show, on the contrary, a relevant lichen growth. The temple was built by using laterite bricks, a natural material common in tropical areas as a weathering product of pre-existing rocks. A preliminary investigation on the patina samples together with ecological considerations excluded a biological origin of the black alteration, thus prompting a more detailed study. In this work, we have investigated the physico-chemical origin of this unusual patina by identifying its mineralogical and chemical composition. Raman and FTIR spectroscopies, SEM-EDS, micro-XRF and XRPD have been applied to characterize the alteration products. Analyses have been performed both on single fragments and on polished cross sections collected from all four temple facades and from one area in the temple interior. Optical observations of the cross sections have evidenced irregularities in the thickness of the patina. Raman and FTIR spectra have revealed that the black layers are mainly composed of manganese minerals (hollandite, romanechite and manganite). This peculiar alteration pattern is interpreted as because of the tropical climatic conditions of Cambodia. Indeed the variation of wet and dry seasons favours the migration of iron and manganese ions and their successive immobilization in regions not directly subject to leaching.

Opals are naturally occurring hydrous silica materials (SiO2*nH2O), characterized by different degrees of crystallinity and crystal structure. Because of their optical properties, opals have been largely used in jewelry and as decorative elements in artworks. For this reason, a complete characterization and a provenance study of this kind of materials is mandatory in order both to avoid frauds and to reconstruct ancient and modern trade routes of gems. In this work, we present a combined spectroscopic (Raman, FTIR) and X-ray powder diffraction (XRD) investigation of nine opals from the main deposits around the world (Australia, Madagascar, Slovakia, Mexico, Honduras and Ethiopia). Four of these samples are the rare and precious fire opals, characterized by an intense red–orange color. Ethiopia, Honduras and Mexico opals showed spectra and diffraction patterns typical of Opal-CT, generally associated to volcanic genesis, while Australia, Madagascar and Slovakia opals are Opal-A type, associated to sedimentary origin. Unexpectedly the fire opal from Brazil behaves as a CT one. The presence of CO2 was detected only in the latter group, and exceptionally in the Honduras sample; FTIR-FPA imaging showed carbon dioxide to be homogeneously distributed inside the gems. Opals-CT are CO2-free and give much more complex FT-IR spectra in the NIR region where H2O combination modes occur. The obtained results are discussed in terms of relevance of the above experimental techniques for geosourcing opals, and contribute to increase the database of the chemical–physical properties of opals.

Opals are naturally occurring hydrous silica materials (SiO2*nH2O), characterized by different degrees of crystallinity and crystal structure. Because of their optical properties, opals have been largely used in jewelry and as decorative elements in artworks. For this reason, a complete characterization and a provenance study of this kind of materials is mandatory in order both to avoid frauds and to reconstruct ancient and modern trade routes of gems. In this work, we present a combined spectroscopic (Raman, FTIR) and X-ray powder diffraction (XRD) investigation of nine opals from the main deposits around the world (Australia, Madagascar, Slovakia, Mexico, Honduras and Ethiopia). Four of these samples are the rare and precious fire opals, characterized by an intense red-orange color. Ethiopia, Honduras and Mexico opals showed spectra and diffraction patterns typical of Opal-CT, generally associated to volcanic genesis, while Australia, Madagascar and Slovakia opals are Opal-A type, associated to sedimentary origin. Unexpectedly the fire opal from Brazil behaves as a CT one. The presence of CO2 was detected only in the latter group, and exceptionally in the Honduras sample; FTIR-FPA imaging showed carbon dioxide to be homogeneously distributed inside the gems. Opals-CT are CO2-free and give much more complex FT-IR spectra in the NIR region where H2O combination modes occur. The obtained results are discussed in terms of relevance of the above experimental techniques for geosourcing opals, and contribute to increase the database of the chemical-physical properties of opals.

This work reports the synthesis and crystal-chemistry of ferri-clinoferroholmquistite in the system Li(2)O - FeO - Fe(2)O(3) - SiO(2) - H(2)O. Ferri-clinoferroholmquistite has a very restricted temperature stability. An almost monophase amphibole product is obtained at 500degreesC for a wide pressure range (1-7 kbar), whereas a Li-bearing pyroxene becomes predominant for T greater than or equal to 600degreesC. The X-ray powder pattern of ferri-clinoferroholmquistite was indexed in the C2/m space group. Refined cell dimensions are: a = 9.489 (2), b = 18.036 (7), c = 5.313 (3) Angstrom; beta = 101.59 (3). Infrared spectra in the OH-stretching region show the presence of a single and very sharp band at 3614 cm(-1), which is assigned to the Fe(2+)Fe(2+)Fe(2+) trimer at the OH-coordinated M1M1M3 octahedra, and a small satellite band at 3644 cm(-1) which was assigned to Li at M3. Mossbauer spectra can be fitted to three doublets assigned to Fe(3+) at M2, Fe(2+) at M1 and Fe(2+) at M3, respectively, with a calculated Fe(2+)/Fe(2+) ratio of 2/3, suggesting a composition close to the nominal one. The spectroscopic data show that synthetic ferri-clinoferroholmquistite has a strongly ordered cation distribution, in agreement with single-crystal refinements done by Caballero et al. (1998) and Oberti et al. (2000) on natural samples with related Li-rich compositions.

This work relates the occurrence and the characterization of fibrous tremolite within the latest pyroclastic deposits of the Colli Albani (Alban Hills) volcano, to the south-east of Rome (Italy). These mineralizations were observed during a systematic rock sampling undertaken to complete the geological survey for the new 1:50,000 map of this volcanic area. The examined specimens were collected inside distal deposits correlated to the last Albano Maar activity, which are geographically located within the boundaries of the Nemi community. Tremolite occurs within both carbonate ejecta and the host pyroclastic rocks. It shows up as whitish to light grey-coloured aggregates of crystals with fibrous aspect and sericeous brightness. Due to the extremely small crystal dimensions, never exceeding 0.5 mu m in diameter, the micro-chemical composition of the fibres could be obtained only by combining P-XRD, SEM-EDX and FTIR methods. Infrared spectroscopy, in particular, proved to be a valuable technique to characterize the studied amphibole. The composition determined is that of a Fe-free F-rich (c. 53 %) tremolite with significant (c. 20 %) richterite components in solid solution. The occurrence of fibrous tremolite in an inhabited place, occurring as natural geological material rather than being due to anthropogenic pollution, should be examined with concern, because it implies complex health and legal responsibilities in the case of mobilization due to extreme climatic events.

The study of magmatic/volcanic volatiles is based on the determination of H2O and CO2 in glasses, assuming they represent the main volatiles reservoirs of volcanic rocks . However, recent works show that some volcanic nominally anhydrous minerals (NAMs) do contain water ( CO2). Leucite (KAlSi2O6) is an anhydrous mineral typical of potassium-rich basic lavas [1]. Recently [2] and [3] studied, using FTIR spectroscopy, a large number of leucites from all volcanic areas of the Roman Comagmatic Region and showed that they typically contain significant amounts, up to several thousand ppm, of structurally bound water. We report here preliminary results of an experimental study aimed at defining pressure and temperature conditions controlling the solubility of H2O into the leucite framework. Experiments were performed in a non end-loaded piston cylinder apparatus, with T in the range 400-800°C and P in the range 200-500 MPa. Leucite fragments were used as starting materials. The fragments were pre-heated at 600 °C and atmospheric pressure in order to abtain completely dehydrated starting material [4]. The anhydrous grains were then introduced in platinum tubes with excess distilled water and run. Single-crystal micro FTIR was used as a technique to analyse the experimental products. Preliminary data show that significant water amounts (650-950 ppm) diffuse into leucite at these conditions. FTIR images show that the crystals run under these conditions for 4 hours are homogeneously hydrated, suggesting a fast H2O diffusion through the feldspathoid matrix, as also suggested by the dehydration experiments done by [4] at 1 atm. References [1] Deer, Howie and Zussman (2004) Rock-forming minerals, 4B. The Geological Society, London. [2] Balassone, Beran, Fameli, Amalfitano, and Petti (2006) Neues Jahrbuch für Mineralogie Abhandlungen, 182, 149-156. [3] Della Ventura, Bellatreccia and Piccinini (2008) Am. Mineral., 93, 1538-1544. [4] Della Ventura, Bellatreccia, and Piccinini (2007) Frontiers in Mineral Sciences, 27-28 June, Cambridge (GB).

We relate here a microchemical and microspectroscopic FTIR (Fourier-transform infrared) study of a set of cordierite samples from different occurrence and with different H2O/CO2 content. The specimens were fully characterized by a combination of techniques including optical microscopy, single-crystal X-ray diffraction, EMPA (electron micro probe analysis), SIMS (secondary ion mass spectrometry), and FTIR spectroscopy. All cordierites are orthorhombic Ccmm. According to the EMPA data, the Si:Al ratio is always close to 5:4; XMg ranges from 76.31 to 96.63 and additional octahedral constituents occur in very weak amounts. Extraframework K and Ca are negligible, with Na up to 0.84 apfu. SIMS shows H2O up to 1.52 and CO2 up to 1.11 wt%. Optically transparent single-crystals were oriented using the spindle-stage and examined by FTIR microspectroscopy under polarized light. On the basis of the polarizing behaviour, the observed bands were assigned to water molecules in two different orientations, and to CO2 molecules in the structural channels. Prior to the quantitative analyses, the samples were examined for their water and carbon dioxide distribution using a focalplane- array (FPA) of detectors. The evidence was that at the m-scale the distribution of H and C in cordierite may be significantly inhomogeneous, particularly for H2O, whose zoning within the crystal can be strongly affected by the geological history of the mineral after its formation. Refined integrated molar absorption coefficients were calibrated for the quantitative microanalysis of both H2O and CO2 in cordierite based on single-crystal polarized-light FTIR spectroscopy. For H2O the integrated molar coefficients for type I and type II water molecules were calculated separately and turned out to be [I]epsilon = 5000 ± 1000 l•mol-1•cm-2 and [II]epsilon = 13200 ± 500 l•mol-1•cm-2, respectively. For CO2 the integrated coefficient is epsilonCO2= 19000 ± 1000 l•mol-1•cm-2.

Beryl is an accessory mineral typical of pegmatitic rocks, with the ideal formula Al2Be3Si6O18 (space group P6/mcc). Its honeycomb structure is characterized by open channels parallel to the c axis. Chemical compositions of natural beryl substantially deviate from the ideal formula owing to complex cationic substitutions. Although beryl is a nominally anhydrous mineral, channels also typically contain H2O and CO2 molecules. H2O within the structure occurs in two distinct orientations, named type I or II, depending on the orientation of the twofold axis of the molecule relative to the c axis of beryl (Wood and Nassau 1968). Because of its size, the linear CO2 molecule is normal to the c axis and parallel to the larger dimension of the channel (Wood and Nassau, 1968; Charoy et al., 1996). Due to its bearing in petrology, the solubility of water and CO2 in the structurally related cordierite has been studied extensively while there are no data for beryl. We report here the preliminary results of an experimental study aimed at defining the solubility mechanisms of carbon dioxide into the beryl channels. Single-crystals of Cr-doped beryl (emerald) synthesized using the flux method by Hautefeuille and Perrey (1888) obtained from the Natural History Museum of Paris were used as starting materials. These crystals show a perfect hexagonal prismatic morphology and a size not exceeding 1 mm in length and 0.5 mm across; due to the synthesis procedures they are CO2-free and contain only few ppm water (Bellatreccia et al., 2008). Experiments were done using a non end-loaded piston cylinder at P in the range 200-500 MPa and T in the range 700-900°C. Samples were prepared as Pt tubes charged with emerald grains mixed with AgCO3 as a source for CO2. The run products were studied by optical methods using a spindle stage and by FTIR microspectroscopy. The results show that P has a strong effect on the solubility of carbon dioxide and that at least 24 hrs are needed to significantly diffuse CO2 into the beryl channels. Measurement of the refraction indexes show that after the treatment with CO2, the " index remains virtually constant while there is a strong increase of !. This is in agreement with the alignment of the linear CO2 molecule perpendicular to the c axis as also confirmed by polarized FTIR micro-spectroscopy. FTIR images obtained using an FPA detector show that carbon dioxide diffuses along the channel direction. References Bellatreccia, F. et al. (2008) N. Jb. Miner. Abh., 185, 11–16 Charoy, B. et al. (1996) Am. Mineral. 81, 395–403. Hautefeuille, P. and Perrey, A. (1888) Compte Rendues Acad. Sci. Paris, 106, 1800–1802. Wood, D.L. and Nassau, K. (1968) Am. Mineral. 53, 777–800.

Naturally leucite crystallizes in the cubic phase, with space group Ia3d (Peacor, 1968). On cooling below T = 625°C it undergoes a phase transition to a tetragonal I4/a form (Mazzi et al. 1976); there are indications, however, that an additional tetragonal phase is stable over a narrow temperature interval (Lange et al. 1986). Palmer et al. (1997) have shown that the displacive phase transition to tetragonal symmetry is due to twisting of tetragonal prisms of corner-linked (Al,Si)O4 tetrahedra about [001] and a collapse of the [111] structural channels with concomitant volume reduction. Although nominally anhydrous (NAM), leucite typically contains significant amounts of water; this feature was reported for samples from Roccamonfina (Balassone et al., 2006) and the Alban Hills volcano (Della Ventura et al., 2008). Della Ventura et al. (2008) have shown in addition that H2O may be significantly zoned, thus providing a potential tool to monitor the evolution of the magmatic conditions with time. More recently, Martucci et al. (2011) studied the dehydration of synthetic B-substituted leucite (KBSi2O6) by synchrotron powder diffraction and concluded that the structural modifications accompanying the tetragonal  cubic transition is associated with the migration of H2O molecules through the [111] channels. We relate here a single-crystal high-T in situ FTIR study of a set of natural inclusion-free leucite phenocrystals occurring within lava flows, pyroclastic rocks or ejecta in the Roman Comagmatic Province. The spectra show broad absorptions in the 4000-3000 cm-1 region consisting of overlapping components around 3604, 3500 and 3250 cm-1. Interestingly, two different types of spectra are observed in the H2O stretching region, indicating that water molecules may be trapped in leucite in two different environments (hereafter “type I” and “type II”). These different H2O types are systematically associated with samples from different volcanic areas, thus suggesting a possible role of the petrological conditions (pressure, temperature) of crystallization on the H2O entrapment in leucite. FTIR-FPA images show significant H2O zoning across the samples; crystals with homogeneously-distributed water were selected for the dehydration experiments, done using a Linkam T600 heating stage fitted under a NicPlan FTIR microscope at University Roma Tre. The evolution of the water loss as a function of T was monitored by measuring the principal H2O water absorption. The data indicate a continuous water loss with a break in the trend; in “type I” leucite the slope change occurs at ~ 500°C, and dehydration is complete at T > 600°C, probably close to the transition temperature. In “type II” leucite, the slope change occurs at ~ 350-400°C, and dehydration is complete at ~ 500°C. This behaviour is compared with isostructural materials like analcime or pollucite. Mazzi, F., Galli, E., and Gottardi, G. (1976) Am. Mineral., 61, 108-115. Peacor, D.R (1968) Z. Kristall., 127, 213-224. D.C. Palmer, M.T. Dove, R.M. Ibberson, B.M. Powell (1997) Am. Mineral. 82, 16-29. G. Balassone, A. Beran, G. Fameli, C. Amalfitano, C. Petti (2006) N. Jahr. Miner. Abh., 182, 149-156 G. Della Ventura, F. Bellatreccia, M. Piccinini (2008) Am. Mineral., 93 1538-1544. Lange, R.A., Carmichael, LS.E., and Stebbins, IF. (1986) Am. Mineral., 71, 937-945.

Beryllium is widely distributed in soils at low levels (crustal abundance 2-6 mg/kg), but it can also occur naturally in higher concentrations in a variety of materials exploited for many industrial applications. Unfortunately, beryllium is also one of the most toxic natural elements and is known to be a human carcinogen. We report and analyse a diffuse, unusually high (up to 80 mg/kg, average approximately 18 mg/kg), natural occurrence of beryllium in pyroclastic layers related to the Pleistocene activity of the Vico volcano (northern Latium). The naturally occurring beryllium content in most of the studied samples is extremely high and even greater than that found in sites contaminated by the accidental release of beryllium into the environment by industrial activities. Only 8 out of the 120 analysed samples gave values below the Italian limit for potentially unacceptable risk for industrial soil-use (10 mg/kg); in no case values below the limit for residential soil-use (2 mg/kg) were observed. Additionally, experiments to define Be leachability have been carried out for selected samples, providing evidence of significant mobility in contrast with data presented in the literature that indicate beryllium as an element with low mobility in oxidising surface environmental conditions. This is a crucial point to consider, because a relatively high mobility under certain pH and redox conditions involve a significant risk factor. The geochemical behaviour of the element explains the anomalous Be concentration values because its incompatibility in common rock-forming silicate minerals is concentrated via fractionation during magma crystallisation. An additional contribution may be related to the volcanic late-stage fluids permeating through the emplaced rocks. Combined mineralogical (optical microscopy, SEM-EDAX, EMPA and X-ray diffraction) and geochemical analyses suggests that the higher beryllium concentration in pyroclastics and associated soils are related to the presence of finely dispersed Be-containing minerals, such as gadolinite (Cámara et al., 2008), or hellandite-group minerals (Oberti et al., 2001). However, the possible presence of Be in volcanic glasses is also presently under investigation. Finally the occurrence of such natural high background concentrations of potentially harmful elements, as it is the case for beryllium studied here, highlights the need for systematic geochemical studies and mapping to produce multi-purpose reference databases for risk assessment and land management. Cámara, F., Oberti, R., Ottolini, L., Della Ventura, G., Bellatreccia, F. (2008) American Mineralogist, 93, 996-1004. Oberti, R., Ottolini, L., Camara, F., Della Ventura, G. (1999) American Mineralogist, 84, 913-921.

Cordierite is a unique case of a microporous mineral stable under geological conditions spanning from the amphibolite facies to UHT metamorphism to crustal anatexis (Harley et al., 2002; Bertoldi et al., 2004). Because of its structural channels, it is able to trap H2O and CO2 (Armbruster and Bloss, 1980), and for this reason the analysis of the volatile constituents of cordierite may help constraining the geological conditions and the composition of coexisting fluids during its formation (Vry et al., 1990; Harley et al., 2002). It follows that the quantitative evaluation of the channel constituents is crucial in petrologic studies. We address here this point by studying, using a multidisciplinary approach, a set of cordierite samples from different occurrence and with different H2O/CO2 content. The aim of the study was a calibration of reliable absorption coefficients to be used for the quantitative microanalysis of H2O and CO2 in cordierite based on single-crystal polarized-light FTIR spectroscopy. The specimens were fully characterized by a combination of techniques including optical microscopy, single-crystal X-ray diffraction, EMP (electron micro probe), SIMS (secondary ion mass spectrometry), and FTIR spectroscopy. All cordierites are orthorhombic Ccmm; the 2Vα optic axis angle is linearly related to the CO2 content. According to the EMP data, the Si:Al ratio is always close to 5:4; XMg ranges from 76.31 to 96.63 and additional octahedral constituents occur in very weak amounts. Extraframework K and Ca are negligible, while Na may reach values as high as 0.84 apfu. SIM spectrometry shows H2O up to 1.52 and CO2 up to 1.11 wt%. Optically transparent single-crystals were oriented using a spindle-stage and examined under polarized light. On the basis of the literature data and the polarizing behaviour, the observed bands were assigned to water molecules in two different orientations and to CO2 molecules in the structural channels. The spectra also show the presence of 13C and 18O, and weak amounts of CO in the samples. FTIR imaging done using the novel FPA detector system clearly shows that at a m-scale the distribution of H and C in this mineral may be significantly inhomogeneous, and this must be taken into account when collecting analytical data for petrological purposes. This feature is probably less important for carbon molecules than it is for H2O, whose distribution within the crystal can be strongly affected by the geological history of the mineral after its formation. Armbruster, T. e Bloss, F. D. (1982) Am. Min., 67, 284-91. Bertoldi, C., Proyer, A., Garbe-Schönberg, D., Behrens, H., Dachs, E. (2004) Lithos 78, 389-409. Harley, S.L., Thompson, P., Hensen, B.J., Buick, I.S. (2002) J Metam Geol 20, 71-86. Vry, J.K., Brown, P.E., Valley, J.V. (1990) Am Min 75, 71-88.

Hydrogen can be a major, a minor or a trace constituent of a large variety of minerals. It is usually bonded to oxygen to give H2O, OH-, or more rarely H3O+, H3O2- H5O2+ units, but also NH4+ or organic compounds. It can be a structural component in stoichiometric hydrates, hydroxides, and in many silicate minerals, or can be non-stoichiometrically present as a major extraframework component in microporous minerals (e.g. zeolites). Hydrogen also occur as a minor constituent in structural defects of nominally anhydrous minerals (NAMs) [1]. H exerts a strong influence on the chemical and physical properties of minerals; hence it has a controlling effect on many high-temperature geological processes (e.g. magma genesis, kinetic of phase transformations, etc.), as well as low-temperature alteration processes. Unfortunately, H is a rather elusive element, specially when it occurs in very low amounts, as in NAMs. Conventional micro-analytical techniques (EMPA) and X-ray diffraction are generally unsuitable to characterize this element; secondary ion mass spectrometry (SIMS) and neutron diffraction are not easily accessible and requires complex, time-consuming, analytical procedures. A possible alternative is offered by spectroscopy: Raman, Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR). FTIR is particularly suitable for hydrogen, since the O-H (C-H and N-H) bond absorbs the infrared radiation very efficiently. The relatively low cost, ease of use and ease of sample preparation makes the FTIR technique an extremely powerful tool for the study of H-bearing minerals [2]. Using FTIR spectroscopy we can: a) quantify hydrogen, b) study its distribution [3], c) distinguish its speciation, d) define the structural orientation of the O-H dipole, e) study phase transitions associated with H loss, and f) study thermal processes [4]. We present here the recent developments of the FTIR activities at Roma Tre and describe the new facilities which are currently available in our laboratories (high temperature stages, Focal Plane Array detectors). We will use, as examples, the most recent results obtained by our group, including studies on beryl, cordierite, feldspathoids, phospates and hydrocarbons-bearing materials. [1] H. Keppler, J.R. Smyth (Eds.) Reviews in Mineralogy and Geochemistry 62 (2006) pp. 478. [2] E. Libowitky, A. Beran, Emu Notes in Mineralogy 6 (2004) 227-279. [3] G. Della Ventura, F. Bellatreccia, A. Marcelli, M. Cestelli Guidi, M. Piccinini, A. Cavallo, M. Piochi, Anal. Bioanal. Chem. 397 (2004) 2039-2049. [4] E. Bonaccorsi, G. Della Ventura, F. Bellatreccia, S. Merlino, Micropor. Mesopor. Mater. 99 (2006) 225-235.

Sideronatrite - Na2Fe3+(SO4)2(OH)•3(H2O) - is a secondary iron-bearing, hydrous sulfate formed during oxidation of pre-existing sulfides. It is a typical sedimentary product in some soils and evaporatic deposits. Sideronatrite is formed in acid, sulfate-rich environments, and plays an important role in the acid drainage mobilization of metals and in the monitoring of water quality. The dehydration behavior of sideronatrite from Sierra Gorda (Chile) was investigated by in situ high-T FTIR spectroscopy. The structural variations induced by thermal treatment were monitored by FTIR using the bending (2) mode of the water molecule around 1650 cm-1, the stretching (3 and 1) modes around 3580 and 3420 cm-1, and the corresponding combinations modes in the wavenumber region 4000-6000 cm-1. The reaction sequence that describes the thermal decomposition of sideronatrite in the range RT-400°C , is the following: sideronatrite → metasideronatrite I → metasideronatrite II → Na3Fe(SO4)3 Na2Fe(SO4)2(OH)∙3H2O Na2Fe(SO4)2(OH)∙H2O Na2Fe(SO4)2(OH) Fe - Na - SO4 During the transformation sideronatrite → metasideronatrite I (Ventruti et al. 2010), only two interstitial water molecules, coordinated by the Na atoms, are lost, while the characteristic framework of the structure of sideronatrite, i.e. the [Fe3+(SO4)2(OH)]∞ chain, remains unchanged both in metasideronatrite I and in metasideronatrite II structures. The loss of OH- group corner-sharing between two adjacent Fe3+-octahedra in sideronatrite chain, involves the break down of the [Fe3+(SO4)2(OH)]∞ chains and the subsequent formation of an intermediate amorphous transitional phase from which the Na3Fe(SO4)3 compound will form later. The first and second reaction (i.e. sideronatrite to metasideronatrite I and metasideronatrite I to metasideronatrite II) are certainly topotactic, whereas the formation of Na3Fe(SO4)3 is a typical nucleation and growth reaction process which originates from metasideronatrite II decomposition through the following reaction: 6Na2Fe(SO4)2OH →4 Na3Fe(SO4)3 + Fe2O3+ 3H2O. The presence of Fe2O3 in the observed diffraction pattern is thus justified as a co-product of the decomposition process. In the recrystallization of Na3Fe(SO4)3 from the amorphous phase, the OH– group is replaced by a (SO4)2– group according to: OH– → (SO4)2– + Na+ to preserve the electro-neutrality of the structure. Such (SO4)2– group, together with two bridging (SO4)2– tetrahedral, already present in sideronatrite chain, provides a further linkage between two consecutive Fe3+-octahedra in Na3Fe(SO4)3 (Fig. 1), to build up infinite [Fe3+(SO4)3] chains, which extend along the c axis.

Arrojadites are extremely complex phosphates which are typically found in granitic pegmatites or hydrothermal veins. Their occurrence in metamorphic rocks [1] suggests wide conditions of formation for these minerals. The crystal structure and crystal chemistry of arrojadite have been debated for several decades, until [2] and [3] re-examined a set of samples from various occurrences and revised the structural model, the formula and the nomenclature of the group. One key aspect in the new crystal-structural model for arrojadite is the presence of three OH-groups [2]: two of these (O-H1 and O-H2) are very similar in local octahedral environment, crystallographic orientation and hydrogen-bond system. In contrast, O-H3 is connected with the apical oxygen of a newly defined tetrahedron in the structure, and is involved in a bifurcated hydrogen bridge with surrounding oxygen atoms. The Raman spectra reported in [2] show two higher-frequency, intense and convoluted bands which were assigned to specific local environments of OH1 and OH2; an additional low-frequency, broad and weak feature in the spectra (Fig. 1, left) could not be assigned with certainty. The FTIR spectra collected in the course of present work on various samples studied in [2], are similar to the Raman spectra in the higher-frequency 3600-3500 cm-1 range, with two intense and multi-component bands. In contrast, in the lower-frequency region, FTIR shows a very intense and broad absorption extending from 3500 to 2900 cm-1 (Fig. 1, right).The FTIR spectrum of arrojadite from Rapid Creek (Yukon) shows also an intense doublet at 3190-3087 cm-1 (Fig. 1 right, top) which can be assigned to NH4+ groups, as confirmed by EMPA only in this sample. The orientation of the absorber (i.e. the O-H bond) with respect to the crystallographic axis can be determined from polarized-light measurements along the principal optical direction [4]. For the arrojadite studied here, the data are consistent with assignment of the higher-frequency components to the O-H1 and O-H2 groups obtained from the Xray structure refinements even in the case of partial occupancy, while the assignment of the broad band to the H-O3 group proposed by [2] needs further work. No evidence of molecular water is present in the NIR 4000-6000 cm-1 region. [1] Demartin, F. et al. (1996) Can. Mineral., 34, 827-834. [2] Cámara, F. et al. (2006) Am. Mineral., 91, 1249-1259. [3] Chopin, C. et al (2006) Am. Mineral., 91, 1260-1270. [4] Libowitzky, E. & Rossman, G.R. (1996) Phys. Chem. Miner., 23, 319-327.

In this work we relate the synthesis and crystal-chemical study of amphiboles along the join richterite - ferrorichterite [nominally Na(NaCa)(Mg5-xFe2+ x)Si8O22(OH)2], at 700°C, 1 kbar, under redox conditions imposed by a MW solid buffer. XRPD shows essentially single-phase run products at both endmember compositions, with minor (10-15%) pyroxene and quartz for intermediate compositions. Interestingly, there is a significant evolution of the amphibole morphology across the solid-solution series: Mg end-member richterite is extremely acicular (length up to 15 μm, diameter up to 1 μm) whereas for increasing Fe in the system the amphibole becomes increasingly stubby, with a length:diameter ratio≈ 3:1 for the Fe -rich endmember. Notably, the refined cell parameters show linear variations across the series, suggesting a complete Mg-Fe2+ solid-solution along the join. The OH-stretching FTIR spectra show complex patterns for intermediate compositions with up to eight bands which can be assigned to the various configurations involving Mg/Fe2+ at M(1,3), locally associated with both full and empty A-sites. Combination of Mössbauer and FTIR spectroscopy however shows that the composition of the amphibole is much more complex than expected just from XRPD data: Fe2+ is in fact disordered among all M-sites, and, despite the strongly reducing conditions during syntheses, there is significant Fe3+ in the amphibole; it is fully ordered at M(2). For increasing Fe in the system, the amount of Fetot in the amphibole is systematically lower than expected as is Fe2+ at the M(1-3) octahedra, while M(2)Fe3+ increases toward more ironrich compositions (Fig. 1). These results definitively stress the need for a proper characterization of the experimental run products because these may depart from the expected stoichiometry in a significant way. Direct EMP or single-crystal X-ray refinement is highly desirable, however spectroscopic methods may provide a valuable alternative, particularly when the Fe3+ vs. Fe2+ composition is needed.

In this paper we describe recent applications of micro-infrared imaging in the Earth sciences. We address, in particular, the use of Fourier-transform infrared (FTIR) spectroscopy in characterizing the zoning and speciation of H and C in a variety of geological materials, including microporous minerals, nominally anhydrous volcanic minerals (NAMs), and crystal inclusions. These investigations show that use of the modern techniques of FTIR imaging enables detection of the zoning of volatile species across the studied samples, and possible configuration changes of structurally-bound carbon molecular species (e. g., CO(2) vs CO(3)) during crystal growth. Such features, which are not accessible with other micro-analytical techniques, may provide information about the physicochemical properties which act as constraints in the genesis of the samples, and important information about the evolution of the geological system. Tests performed with focal-plane-array detectors (FPA) show that resolution close to the diffraction limit can be achieved if the amounts of the target molecules in the sample are substantially different. We also point out the possibility of using FTIR imaging for investigations under non-ambient conditions.

Mesoporous and dense sol-gel titania films have been synthesized and processed in similar conditions to make a comparative study of crystallization to anatase in porous and dense samples. We have performed a correlative analysis combining THz spectroscopy with synchrotron radiation, variable angle incidence infrared spectroscopy, spectroscopic ellipsometry and grazing incidence X-ray diffraction to characterize the structure of titania films as a function of thermal processing conditions. THz spectra have shown that small anatase crystalline clusters are already present in the as-deposited samples, and both crystallization and growth process are favored in the mesoporous films. Moreover, the analysis by X-ray diffraction and variable angle incidence infrared spectroscopy has allowed identification of the presence of small textures in the samples.

Melt inclusions (MIs) are micrometric-sized and variable-shaped impurity parcels of glass vesicles solids present within cavities or fractures of crystals. Because representing melt droplets that were trapped during crystal growth, they are believed to record the variable physico-chemical conditions of the hosting multi-phase system. Therefore, MIs are unique probe of near-liquidus magmatic conditions, otherwise inaccessible to Earth Scientists, and are widely used to integrate and corroborate conventional petrological and volcanological techniques based on mineral phases and whole rocks. Electron microprobe (EMP-WDS) and microscopy (SEM-EDS), and Fourier Transform Infra Red (FT-IR) spectroscopy are well-established analytical techniques, commonly used to determine composition of the magma from which MIs formed. Noteworthy, FT-IR is usually adopted to determine the content of dissolved H2O and CO2, providing i) essential information for entrapment pressures, hence depths of crystal growth, and ii) constraints to the volatile budget of magmas. Assessing such volatile contents has significant implications for the understanding of magma evolution and migration, from the depths of parental magma genesis, through the main depths of crustal storage, up to surface. The MI-based quantification of volatile contents and the recognition of degassing patterns are also vital for deciphering magma rheology, which largely affects eruptive dynamics and style. Limits to melt inclusion studies are i) their typically very small size (< 100 m), ii) the possible late and secondary crystallization, iii) the diffusivity-driven chemical exchange between melt and host crystal, iv) and the alteration phenomena that mask or even delete the original melt composition. Here, we present a study of glass/melt inclusions in phenocrysts from Procida Island (Phlegraean Volcanic District, South Italy), analyzed for combined SEM-EDS electron microscopy, EMP-WDS microchemistry and FT-IR spectroscopy. In particular, we have characterized the distribution of volatile H and C species across both the host crystals and the inclusions, by using a focal-plane-array (FPA) of detectors. The FPA technique allows the acquisition of a large number of IR spectra simultaneously and generate mid-IR images with high resolving power of the target molecules in the H-O-C system. The integration of these analytical techniques is a mandatory step in order to provide definite advances in MI characterization and data interpretation

In this paper we describe recent applications of micro-infrared imaging in the Earth sciences. We address, in particular, the use of Fourier-transform infrared (FTIR) spectroscopy in characterizing the zoning and speciation of H and C in a variety of geological materials, including microporous minerals, nominally anhydrous volcanic minerals (NAMs), and crystal inclusions. These investigations show that use of the modern techniques of FTIR imaging enables detection of the zoning of volatile species across the studied samples, and possible configuration changes of structurally-bound carbon molecular species (e.g., CO2 vs CO3) during crystal growth. Such features, which are not accessible with other micro-analytical techniques, may provide information about the physicochemical properties which act as constraints in the genesis of the samples, and important information about the evolution of the geological system. Tests performed with focal-plane-array detectors (FPA) show that resolution close to the diffraction limit can be achieved if the amounts of the target molecules in the sample are substantially different. We also point out the possibility of using FTIR imaging for investigations under non-ambient conditions.

The crystal structure and crystal chemistry of two natural pollucite samples, from Buckfield, Oxford County, Maine (sample M3), and from Kanzit Mawaie, Laghman, Nooristan, Afghanistan (sample N5), have been investigated by means of wavelength-dispersive X-ray microanalysis, thermogravimetric analysis, single-crystal X-ray and neutron diffraction, and single-crystal Fourier-transform infrared spectroscopy. The X-ray and neutron diffraction patterns of the two pollucite crystals show a metrically cubic unit cell [with aM3 = 13.6914(6) Å and aN5 = 13.6808(6) Å by neutron diffraction data; the deviation from isometry is 4σ(Fo) for M3 and R1 = 0.0693 for 31 refined parameters and 331 unique reflections with Fo > 4σ(Fo) for N5. The structure refinements show a disordered Si/Al-distribution in the tetrahedral framework. The analysis of the difference-Fourier maps of the nuclear density confirms the presence of extra-framework water molecules with oxygen sharing the Cs site (at 1/8, 1/8, 1/8, Wyckoff-16b position). However, the minima, ascribable to the proton sites, are very weak in density. Two possible proton positions, leading to a reasonable H2O configuration, are given, and the possible hydrogen bonding is described. Sodium is located at 1/4, 1/8, 0 (Wyckoff-24c position). The main IR absorption bands in the regions typical of H2O are assigned, and the presence of hydroxyls in the studied samples is ruled out. Neutron diffraction and FTIR data agree with the presence of very weak hydrogen bonds in the structure. The detailed description of the crystal structure and crystal chemistry of pollucite (e.g., Si/Al-distribution, configuration of the extra-framework content, possible hydrogen bonding scheme) reported in this study is the key to understand the high thermo-elastic stability of pollucite, the immobility of Cs at non-ambient conditions, and the extremely low leaching rate of Cs, which make this open-framework silicate a promising material with potential use for fixation and deposition of Cs radioisotopes.

Fourier-transform infrared (FTIR) microscopy is a modern analytical technique able to provide a molecular imaging of a complex sample. With this technique, based on the absorption of IR radiation by vibrational transitions in covalent bonds, unique images with a high spatial resolution can be obtained from a sample. The spatial resolution of an infrared microscope, as defined by the diffraction limit, is about 2λ/NA, i.e., from 3 to 4 times the wavelength depending by the NA (numerical aperture) of the instrument. In these last decades the availability of solid-state array detectors revolutionized the fields of molecular spectroscopy and chemical imaging. Nowadays, 2-dimensional IR detectors, Focal Plane Arrays (FPAs), coupled to synchrotron radiation sources allow achieving the highest sensitivity and the highest resolution of molecular imaging in a short time. FPA arrays, composed by small IR detectors (pixels), allow the acquisition of thousands of IR spectra simultaneously and generate mid-IR images with high resolving power, thus improving performances of IR imaging systems equipped by conventional IR sources. A microscope equipped with a FPA has no apertures and its sensitivity is associated to the pixel size: the effective “aperture” of the optical system. FPAs enable different imaging modalities with a resolution of a few microns (depending on the pixel size and magnification of the objective). Massive and fast data collection is possible with a drastic reduction in the acquisition time compared to a confocal geometry. Experiments performed with conventional instrumentations have clearly shown that combining the sensitivity and the speed of read-out of the last generation of FPAs the time may scale down from hours to minutes (Barghawa and Lewin, 2001, Petibois et al., 2008). H-C-O functional groups are characterized by highly polar bonds and absorb infrared radiation with high efficiency, therefore FTIR micro-spectroscopy may be used to qualitatively and quantitatively measure these elements in geological materials (both minerals and glasses) with a high-spatial resolution (Wysoczanski and Tani, 2006; Della Ventura et al., 2009). We will present here and discuss new applications of infrared imaging, with particular reference to the distribution and speciation of H and C in a variety of mineralogical samples, including single-crystals (microporous minerals, NAMs, fluid inclusions) and thin sections, as well as the use of FTIR imaging in high-temperature studies. References Barghawa, R. and Lewin, I. (2001) Anal. Chem. 73, 5157-5167. Petibois C., Piccinini M., Cestelli-Guidi M.A., Déléris G. and Marcelli A. (2009) Nature Phot. 3, 177 Della Ventura, G., Bellatreccia, F., Cesare, B., Harley, S., Piccinini, M. (2009) Lithos, accepted. Wysoczanski, R., Tani, K. (2006) J. Volcan. Geoth. Res., 156, 302-314.

Nonstoichiometric REEAl2.07(B4O10)O0.60(REE=(La, Ce); Ce; Nd) dimetaborates have been crystallized and analyzed by means of single crystal X-ray diffraction. The compounds resulted to be isostructural within hexagonal space group P62m (n. 189), with the following unit cell parameters: a = 4.6060(6) Å, c = 9.3510(8) Å and V = 171.81(3) Å3 (La, Ce); a = 4.5960(6) Å; c = 9.3170(10) Å and V = 170.44(4) Å3 (Ce); a = 4.5830(7) Å, c = 9.2810(14) Å and V = 168.82(4) Å3 (Nd). The REE cations are surrounded by six oxygen atoms, making up a trigonal prismatic coordination; Al cation is surrounded by five oxygen atoms, resembling a square pyramidal coordination, while the BO4 group displays tetrahedral arrangement. The three-dimensional framework can be described as a mica-like structure packed down crystallographic axis c, with layers of six-membered rings of B tetrahedra alternated by inter-layers REE cations and layers of Al polyhedra. A complex network of REE...O and Al...O interactions concur to stabilize the framework.

This paper reports an infrared spectroscopic study of a set of sodalite-group minerals. The specimens have been identified using a combination of X-ray diffraction and microchemical analysis. As expected, the Si/Al ratio is ~1; the extra framework cation content is characterized by a well-defined Na > (Ca+K) substitution. The lattice parameters of the studied samples range from sodalite (sample LM11) with a = 8.889(2) Å , to haüyne (sample HR3S) with a = 9.1265(2) Å . The specimens, having the SO42- group as a dominant anion, show a clear correlation between the a cell edge and the K content. Singlecrystal FTIR spectroscopy shows that haüyne and nosean typically contain enclathrated CO2 molecules, inadditionto H2O and minor carbonate, while sodalite is virtually CO2-free. Detailed microspectrometric mappings show a non-homogeneous distribution of volatile constituents across the crystals, which may be related to the presence of fractures in the crystals. Because of such zoning, a relatively wide variation is observed when calibrating extinction coefficients on the basis of a bulk analytical method such as CHN elemental analysis.

Masutomilite is a rare Mn-analogue of the Li-mica zinnwaldite; it was described by Harada et al. (1976) from the Shiga Prefecture, Japan, and later reported from few other localities (Němec, 1983, Čerńy and Burt, 1984). We relate here an infrared study of two masutomilite specimens from Central Urals, Russia (Mokrusha Pegmatite, Murzinka Region) and Idaho, USA (Sawtooth Mountains, Boise County), respectively. Both samples belong to the 1M polytype. The chemical composition, derived by combining electron microprobe analysis, inductively coupled plasma atomic emission spectrometry (ICP-AES) for Li, and results from the structure refinement are, on the basis of O10(F,OH)2 (Brigatti et al., 2007): (Si3.30Al0.70) (Al1.00Fe0.36Mg0.01Mn0.31Li1.32) (Ca0.01Na0.04K0.94) O10F1.91(OH)0.09 (Mokrusha mine, Russia) and (Si3.11Al0.89) (Al0.91Ti0.02Fe0.46Mg0.03Mn0.52Li1.06) (Na0.05K0.92Rb0.02) O10F1.89(OH)0.11 (Sawtooth Mountains, Boise County, Idaho, USA). Both samples have all Li > 1.0 apfu and variable Fe/Mn. The anionic site is dominated by F with low amounts of OH (0.09-0.12 apfu). Single-crystal, polarized-light FTIR spectra were collected using a NicPlan microscope equipped with a nitrogen-cooled MCT detector, a KBr beamsplitter and a gold wire grid polarizer, at 4 cm-1 resolution. The spot size was ~ 100 μm and 128 scans were averaged for each spectrum. The collected patterns are different as expected from the different chemical composition of the examined samples, however they show broad similarities and a similar behaviour under polarized light. They consist of a higher-frequency component which is centred at 3685 and 3659 cm-1 for masutomilite from Russia and Idaho, respectively; both bands are strongly polarised for E // α. A broader, multicomponent absorption is observed at around 3600 cm-1. In masutomilite from Idaho this band is split in two components of equal intensity, at 3685 and 3659 cm-1 respectively, plus a lower-frequency shoulder at ~ 3552 cm-1. This band shows maximum intensity for E // γ and a medium intensity for E // α, while showing reduced intensity for E // β. A lower frequency, broad band is finally present at ~3500 cm-1 in both samples; this feature is virtually unaffected by rotation of the polarizer. Following the model of Robert et al. (1989) for Li-bearing micas, the higher frequency bands at 3685 - 3659 cm-1 are assigned to OH-dipoles bonded to FeFeFe local environments (TRI-6 environments), while the multicomponent band around 3600 cm-1 is assigned to AlM2+M2+ (with M2+ = Fe or Mn) local environments (TRI-7 environments). The spectra show that all Li is associated to F at the anionic site. From measurement of the dichroic ratio (absorbance along a / absorbance along b, e.g. Serratosa and Bradley, 1962, Vedder and McDonald, 1963) the orientation of the O-H vectors with respect the (001) plane can be evaluated. References Brigatti, M.F., Mottana, A., Malferrari, D. and Cibin, G. (2007) Am. Mineral., 92, 1395-1400. Harada, K., Honda, M., Nagashima, K., Kanisawa, S. (1976) Min. J., 8, 95-109. Němec, J. (1983) Neues J. Miner., Mh., 537-540. Robert, J.-J., Beny, J.-M., Beny, C., Volfinger, M. (1989) Can. Mineral., 27, 225-235. Serratosa, J.M. and Bradley, W.F. (1962) Determination of the orientation of OH bond axis in layer silicates by infrared absorption. J. Phys. Chem., 62, 1164-1167. Vedder, W. and McDonald, R.S. (1963) Vibrations of the OH ions in muscovite. J. Chem. Phys., 38, 1583-1590.

The study of volatile constituents in minerals has potential applications ranging from environmental studies to ore research to volcanic hazards. In this paperwe present newdata on the volatile (particularlyCO2) content of a series of feldspathoids belonging to the cancrinite-sodalite group of minerals, in combination with other data collected over the last few years. The work has been essentially done using FTIR microspectroscopy to detect and characterize the speciation of H and C in the micropores of these minerals. We show that most cancrinite-sodalite group of minerals are able to trap CO2 in their structure in addition to other molecular and anionic species such as H2O, OH, F, Cl, SO4, SO3 etc. A combination of in situ and annealing heat-treatments shows that the different species in the cancrinite-sodalite group release CO2 at different temperatures, due to the different connectivity of their pores.Detailed FTIR microspectrometry mappings typically show non-homogeneous distributions of hydrogen and carbon across the samples, and suggest a possible use of these minerals as a tool for geothermometric modelling. The finding that most cancrinite-sodalite group minerals are able to trap carbon dioxide opens a new frontier in the design of materials having potential for carbon sequestration from the atmosphere.

The study of volatile constituents in minerals has potential applications ranging from environmental studies to ore research to volcanic hazards. In this paperwe present new data on the volatile (particularly CO(2)) content of a series of feldspathoids belonging to the cancrinite-sodalite group of minerals, in combination with other data collected over the last few years. The work has been essentially done using FTIR microspectroscopy to detect and characterize the speciation of H and C in the micropores of these minerals. We show that most cancrinite-sodalite group of minerals are able to trap CO(2) in their structure in addition to other molecular and anionic species such as H(2)O, OH, F, Cl, SO(4), SO(3) etc. A combination of in situ and annealing heat-treatments shows that the different species in the cancrinite-sodalite group release CO(2) at different temperatures, due to the different connectivity of their pores. Detailed FTIR microspectrometry mappings typically show non-homogeneous distributions of hydrogen and carbon across the samples, and suggest a possible use of these minerals as a tool for geothermometric modelling. The finding that most cancrinite-sodalite group minerals are able to trap carbon dioxide opens a new frontier in the design of materials having potential for carbon sequestration from the atmosphere.

We relate here a combined single-crystal polarized-light FTIR (Fourier transform infrared) and neutron diffraction study of two natural cancrinites from Cameroun and Canada, respectively. Electron microprobe analyses show both samples to be almost end-member carbonate-cancrinites [ideal chemical formula Na6Ca2(Si6Al6O24)(CO3)2•2H2O]. The structural refinements show that the extra-framework content in the large 12-membered rings channels is represented by one independent Na-site (Na2) and two independent, and statistically distributed, CO3 groups. The geometry of the CO3 groups appears to be almost regular, with C1-OC1 ~ 1.298(7) Å and C2-OC2 ~ 1.300(5) Å, in agreement with the previous studies [1,2,3]. The atoms of the carbonate-groups are not perfectly coplanar, being z(C1) ≠ z(OC1) and z(C2) ≠ z(OC2). The H2O molecules and a further Na-site (Na1) lie in the cancrinite-cage; the H2O oxygen site (OW) lies off from the triad axis, giving rise to a statistical configuration with three equivalent and mutually exclusive water molecules, as already suggested by [1,2]. The high-quality neutron data show that the water molecule is almost symmetric, with very similar Ow-H1 and Ow-H2 bond-distances, and is slightly tilted from the (0001) plane. It is involved in bifurcated hydrogen bridges, with two possible bonds for H1 (i.e. OW-H1•••O2 and OW-H1•••O4) and two for H2 (i.e. OW-H2•••O3 and OW-H2•••O2). The Ow•••O donor-acceptor distances are all > 2.7 Å. The polarised-light FTIR spectra show two main absorptions, at 3602 and 3531 cm-1, respectively. The former is polarised for E  c, while the latter is polarized for E  c. On the basis of the neutron diffraction data, the 3602 cm-1 band is assigned to the anti-symmetric stretching mode (ν3), while the 3531 cm-1 band is assigned to the symmetric stretching mode (ν1) of the same water molecule, in agreement with the presence of a single bending mode at 1630 cm-1. One additional weak component at 4108 cm-1 could possibly indicate the presence of low amounts of additional OH groups in the structure of cancrinite. Several overlapping bands in the 1300-1500 cm-1 range are strongly polarized for E  c, and are assigned to the vibrations of the CO3 group. References. [1] H.D. Grundy, I. Hassan, Can. Mineral., 20, 239-251, 1982; [2] P. Ballirano, A. Maras, Eur. J. Mineral., 16, 135-141, 2004; [3] I. Hassan, S.M. Antao, J.B. Parise, Am. Mineral., 91, 1117-1124, 2006.

The P21/m ↔ C2/m phase-transition has been studied by high-T FTIR analysis on a series of synthetic amphiboles in the Li2O–Na2O–MgO–SiO2–H2O (LNMSH) system. Spectra were collected in the T range 25–450 °C on KBr disks. All examined amphiboles have P21/m symmetry at room T. Their OH-stretching FTIR spectrum consists of two main bands at ∼ 3740 and 3715 cm−1. At the transition temperature (Tc), these bands merge into one single absorption centred at ∼ 3720 cm−1, and no further change is observed beyond this T. Significant modifications consisting in peak shifting and band broadening are also observed in the MIR (medium infrared) 1300–640 cm−1 region. Tc values for the different compositions were estimated based on various methods; the most reliable procedure is considered to be the fit of Landau 2-4-6 potentials using band shifts observed in the MIR region. The Tc values obtained for all samples are consistent with previous results obtained on two members of the series examined here by single-crystal or synchrotron powder HT-XRD (high-T X-ray diffraction). They correlate linearly with the aggregate cation radius at M(4) [Tc (°C) = 803–533 ; R2 = 0.97]. This work thus provides a measure of the role played by the size of the M(4) polyhedron in determining the Tc in simple chemical systems where the B-site occupancy (and geometry) is the only variable. The slope of the equation is far less steep in the LNMSH system than in cummingtonite; crystal-chemical reasons for this behaviour are discussed, and the local order between A and monovalent B cations is suggested to be the major constraint. In more complex systems, inspection of the available data shows that other factors such as the aggregate size of the strip of octahedra must be taken into account.

This paper describes a single-crystal polarised-light FTIR study of the original emerald synthesised by Hautefeuille & Perrey (1888) using the flux method. The microchemical data show the analysed sample to be very close to the stoichiometric composition and homogeneous except for a significant variation in the Cr2O3 content (from 1.45 to 2.59 wt%). Trace amounts of Ti, Mg, Fe, Zn, Na, K and F were also detected. The cell parameters are (in Å) a = 9.2264(25) and c = 9.1904(2), c/a = 0.9961. Despite the synthesis conditions, FTIR spectra in the OH-stretching region show the presence of weak but significant H2O vibrations in the crystals. The polarised FTIR spectra collected with E⊥c consist of a unique sharp and intense band at 3643 cm-1, whereas the E//c spectra consist of two minor bands at 3643 and 3587 cm-1. These bands are assigned to the ν3 antisymmetric stretching, and ν1 symmetric stretching modes of type II water in the structural channels, respectively. These water molecules are probably associated with Li impurities in the mineral, due to the flux employed for the syntheses. Using the molar absorption coefficient εi = 27126 l * mol-1 * cm-2 from the calibration curve of Libowitzky & Rossman (1997), a water content of ∼ 30 ppm is derived for the studied emerald.

The principal goal of the Rome group is studying crystalline materials, especially minerals: MS information (Fe oxidation state, Fe3+/Fetot ratios, Fe ions ordination number, Fe atoms aggregation state) is used together with stmchlral and chemical data collected on the same single-phase material to retrieve the topochemical model and to explain the physical properties. Outstanding materials shldied so far are: nahlral and synthetic spinels, natural borosilicates (tourmaline and axinite), natural amphiboles (especially fibres), natural and synthetic zeolites, but also obsidian, pumice, day and other heterogeneous materials.

All updated data of scientific and historical interest on the 15 mineral species first described in Rome and in the surrounding area i.e., from lake Bracciano, to the North, to lake Nemi, to the South, are assembled and discussed. Their typical morphologies are also presented as photographs. In addition, a full list of all minerals described over the area is given. A distinction is made between minerals occurring as euhedral, conspicuous crystals and those present as rock forming grains. Most minerals are discussed with reference to their significance for establishing the pressure and temperature conditions at which they formed, with special attention for those occurring in the lavas and pyroclastics related either to the Sabatini volcanic complex or to the Alban Hills volcano, both belonging to the world-renowned Roman Comagmatic Region. The few sedimentary minerals of palaeomagnetic and geothermal significance in the Tiber valley and in ancient lakes and ponds scattered through the Roman campaign are also listed and briefly discussed.