305,241 research outputs found
Lacalamita, M., Mesto, E., Mongelli, G., Mameli, P., Cerri, G., Pinto, D., Buccione, R., Schingaro, E. 2023. Characterization of Red Muds as valuable resource for sustainability. Convegno Nazionale Italiano sui Geopolimeri. Bari February, 16-17 2023.
No full textAn in situ HT-HP single crystal X-ray diffraction study of armstrongite, a microporous zirconium silicate
No full textArmstrongite, CaZr[Si6O15]·2H2O, is a natural “zeolite-like” Zr-silicate with a heteropolyhedral framework consisting of SiO4 tetrahedra and ZrO6 octahedra that form cavities occupied by Ca-exchangeable cations (Mesto et al., 2014). The behavior at non ambient conditions of armstrongite from Khan Bogdo deposit (Gobi, Mongolia) was studied by in-situ High Temperature Single Crystal X-ray Diffraction (HT SCXRD), both in air and under dry conditions up to 500°C and 375 °C respectively, and by in-situ High Pressure Single Crystal X-ray Diffraction (HP SCXRD) using synchrotron X-ray diffraction data (collected up to 8.01 GPa), a diamond anvil cell and the mix methanol:ethanol:water as hydrostatic pressure-transmitting fluid.
On heating an abrupt discontinuity in the trend of the cell parameters and unit-cell volume occurs at T = 275°C in dry condition and at T = 450°C in air. The cell volume decreased by ~7.5%, compared to that measured at RT, and is compatible with the loss of the two water molecules. The dehydrated phase (solved and refined at 275°C only under dry conditions) exhibits the same space group (C2/m) as RT armstrongite, significantly shortened a and b cell dimensions, increased β angle, and smaller unit-cell volume (a = 13.406(3), b = 13.752(3), c = 7.811(2) Å, β = 110.22(3)°, V = 1351.3(5) Å3) with respect to the hydrated phase (a = 14.0135(7), b = 14.1234(6), c = 7.8388(4) Å, β = 109.401(4)°, V = 1463.4(1) Å3) at RT. The process is also accompanied by the distortion of the cavities as a consequence of Ca splitting and positional disorder of tetrahedral framework oxygens. The dehydration/rehydration process of armstrongite is completely reversible as also found from previous HT XRPD investigation (Schingaro et al., 2018).
HP SCXRD data show a first-order phase transition between 4.01(5) and 5.07(5) GPa. In the high-pressure polymorph, the unit-cell volume triplicates. The bulk compression of armstrongite is mainly accommodated through the tilting of both SiO4 tetrahedra and ZrO6 octahedra around the shared oxygen hinges. The high-P polymorph of armstrongite is found to be stiffer (KV0 increase of ~ 66%), and a remarkable change of the elastic anisotropic scheme occurs. No evidence of crystal-fluid interaction, with a selective sorption of molecules of the pressure-transmitting fluid through the cavities, was observed.
Mesto, E., Kaneva, E., Schingaro, E., Vladykin, N., Lacalamita, M. & Scordari, F. (2014): Armstrongite from Khan
Bogdo (Mongolia): crystal structure determination and implications for zeolite-like cation exchange properties. Am.
Mineral., 99, 2424-2432.
Schingaro, E., Lacalamita, M., Mesto, E. & Della Ventura, G. (2018): Thermal stability and dehydration of armstrongite,
a microporous zirconium silicate. Micropor. Mesopor. Mat., in press
2. Percorsi di inclusione dei migranti nella città metropolitana di Bari tra frammentazione e polarizzazione dei servizi
No full textIl contributo prende in esame il sistema dei servizi per i migranti e la sua organizzazione spaziale nella città metropolitana di Bari (CMB), un territorio caratterizzato da crescente eterogeneità, dovuta anche all'aumento dei flussi di mobilità umana, che sta generando inevitabili continue negoziazioni tra estraneità e incontri interculturali. Mediante un'analisi quantitativa e qualitativa, esso prova a comprendere - e a sviluppare una riflessione critica su - dinamiche e processi di inclusione dei migranti che vivono in questo territorio metropolitano
Buccione R., Cerri G., Cisullo C., Lacalamita M., Mameli P., Mesto E., Mongelli G., Pinto D. & Schingaro E. 2023. Geochemistry and mineralogy of bauxite residues (red muds) from Porto Vesme (Sardinia): from disposal material to new resource. Congresso congiunto SIMP-SGI-SOGEI-AIV “The Geoscience paradigm: resources, risk and future perspectives”, 19-21 Settembre 2023, Potenza.
No full textArmstrongite at non ambient conditions: An in-situ high temperature single crystal X-ray diffraction study
No full textThe dehydration process of armstrongite, CaZr[Si6O15]·2H2O, from Khan Bogdo deposit (Gobi, Mongolia) was studied by in-situ High Temperature Single Crystal X-ray Diffraction (HT SCXRD) in air from 25 to 500 °C and in N2atmosphere from 25 to 375 °C. An abrupt discontinuity in the trend of the a and b parameters and of the unit-cell volume was observed at T = 275 °C in dry conditions and at T = 450 °C in air. This discontinuity is associated to dehydration and to a first-order transition. When compared to RT armstrongite, the dehydrated phase structure (obtained at 275 °C only under dry conditions) is characterized by the same space group (C2/m), cell volume decrease of ∼7.5%, compatible with the loss of the two water molecules, positional disorder of Ca over three sites, splitting of some of the heteropolyhedral framework oxygen atoms, tilting of Zr octahedra and Si tetrahedra and, distortion of four-, six- and eight-membered channels. Differently from other Zr-silicate structures, the channels dimension of the dehydrated structure (defined as the ratio between the longest and shortest diagonals of the channels) allowed the armstrongite structure to completely recover the structural water after 21 days exposure to humid conditions
Cristallochimica e significato petrogenetico dei granati titaniferi del complesso alcalino-carbonatitico di Tapira (Brasile).
No full textPlinius (supplemento italiano all¿European Journal of Mineralogy
Fluorophlogopite and F-rich phases in limestone clasts from the Campanian Ignimbrite quarried at Fiano (southern Italy): mineralogical, geochemical and volcanological insights.
No full textFluorine-rich metamorphosed xenoliths associated to the distal Campanian Ignimbrite (CI) tephra (Campania region,
southern Italy) have long attracted the interest of the mineralogical community (i.e. Scacchi, 1890; Zambonini, 1919;
Masi & Turi, 1972; Balassone et al., 2002). These rocks derive from the Mesozoic carbonate lithotypes of the
Campanian Apennine, embedded in the pyroclastic flow and presently resting at the bottom of the tuff formations. The
sedimentary protoliths suffered from the action of hot, volatile-rich pyroclastic flow, and consequently were affected by
thermal metamorphism to various degrees. Their peculiarity is the occurrence of F- and Mg-bearing phases, with an
ubiquitous presence of neoformed fluorite. The occurrence at Fiano quarries (the so-called “Tufare”) is the classical
locality for these rock xenoliths. Similar rocks were also found in the CI of the Caserta area, and in the Latium region
(Colli Albani). This research aims both at a crystal chemical study of fluorophlogopite occurring in the Fiano xenoliths,
and at a geochemical and volcanological survey, to constrain the petrogenesis processes related to this rare F-, Mg-rich
assemblage and to CI.
The analysed samples belong to two lithotypes: mica-bearing clasts and variably metamorphosed carbonate blocks.
The former lithotype is represented by abundant fluorite, followed by fluorophogopite, F-rich chondrodite, fluoborite,
diopside and (Fe,Mg)-oxides. Minor to trace contents of calcite, humite, tremolite, and grossular also occur. Carbonate
rocks can show calcite only, or also trace amounts of fluorite. The Fiano micas composition approaches that of the
Vesuvius micas from the 1872 eruption (Balassone et al., 2013). The micas belong to the 1M polytype and have crystal
chemical features typical of fluorophlogopites i.e., low c lattice parameter (~ 10.13 Å), (~ 2.060 Å) and (~ 3.135 Å)
distances. New data on minor to ultratrace elements amounts found in the studied clasts, together with Carbon and
Oxygen isotope data will be reported and interpreted in a petrogenetic and volcanological frame.
Balassone G., Franco E., Mattia C.A., Petti C. & Puliti R. 2002. Re-examination of fluosiderite, an unknown mineral
from southern Italy: equal to fluorine-rich chondrodite. Eur. J. Min., 14, 151-155.
Balassone G., Scordari F., Lacalamita M., Schingaro E., Mormone A., Piochi M., Petti C. & Mondillo N. 2013.
Trioctahedral micas in xenolithic ejecta from recent volcanism of the Somma-Vesuvius (Italy): crystal chemistry and
genetic inferences. Lithos, 160-161, 84-97.
Masi U. & Turi B. 1972. Frazionamento isotopico del carbonio e dell'ossigeno negli inclusi calcarei metamorfosati del
"Tufo grigio campano" Auct. di Fiano (Salerno). Per. Min., 41, 291-310.
Scacchi A. 1890. La regione vulcanica fluorifera della Campania. Mem. R. Com. Geol. It., I, 1-48.
Zambonini F. 1919. Il tufo pipernoide della Campania e i suoi minerali. Mem. Descr. Carta Geol. It., 7, 130 pp
Cation-site partitioning in Ti-rich micas from Black Hill (Australia): A multi-technical approach
No full textThe crystal chemistry of Ti-rich trioctahedral micas of plutonic origin, cropping out at Black Hill (South Australia) has been investigated by combining electron microprobc analysis, single crystal X-ray diffraction, Mossbauer spectroscopy and X-ray photoelectron spectroscopy. Chemical analyses have shown the samples taken to be quite homogeneous and Ti-rich (TiO2 approximate to 7 wt.%). Mossbauer investigation yielded Fe2+/Fe3+ approximate to 30. X-ray photoelectron spectroscopy analysis seems to suggest the occurrence of three Ti species: octahedral Ti4+(60%), octahedral Ti3+(26%), and tetrahedral Ti4+( 14%). The analyzed sample belongs to the 1Mpolytype and the relevant crystal data front structure analysis are: a 5.347(l) angstrom, b = 9.261(2) angstrom, c = 10. 195(2) angstrom,beta - 100.29 degrees (1). Anisotropic structure refinement was performed in space group C2/m, and converged at R 2.62, R-w - 2.80. Structural details (the c cell parameter, the off-center shift of the M2 cation towards O4, the bond-length distortions of the cis-M2 octahedron, the interlayer sheet thickness, the projection of K-O4 distance along c*, the difference (outer)(inner)) support the occurrence of the Ti-oxy substitution (R-VI(2+) + 2(OH)(-) reversible arrow Ti-VI(4+) + 2O(2-) + H-2) in the sample. Analysis of structural distortions as a function of the Ti content revealed that the positions of the oxygens 03 and 04 are displaced in opposite senses along [100]. This produces an enlargement of the M1 site with respect to the M2 site and a shortening of the interlayer distance. This trend seems to be in common with other Ti-rich 1M micas of plutonic origin
Manufatti metallici: cultura umanistica e scientifica strettamente interconnessi
No full textSecondo Tucidide, lo scopo dell'archeologia era di "dimostrare di ricostruire il passato non solo attraverso le fonti ma anche attraverso prove scientifiche esatte” evidenziando, quindi, la stretta correlazione che esiste fra cultura umanistica e scientifica (Artioli, 2010). Ecco che i reperti archeologici rinvenuti in aree di scavo o in ritrovamenti subacquei, debitamente interrogati possono raccontarci, in maniera dettagliata, tradizioni, usi, itinerari di viaggio, scambi commerciali delle civiltà che hanno popolato in passato i territori (Parmeggiani, 2003).
La presente ricerca si è focalizzata sullo studio di reperti metallici ritrovati duranti gli scavi archeologici nell’area Siris di Policoro (Matera) al fine di ottenere informazioni sulle caratteristiche chimico – fisiche degli oggetti, sulle tecnologie di realizzazione e sullo stato di degrado/corrosione.
I reperti, consistenti in: specillo (Fig.1), punta di freccia, tappo di fiaschetta, bastoncino in piombo, arma in ferro, punta di giavellotto e fibula sono stati analizzati attraverso una sinergia di metodologie non distruttive quali Microscopia Ottica (MO), Fluorescenza dei Raggi X (XRF), Diffrazione di Raggi X (XRD), X-ray Photoelecton Spectroscopy (XPS) e Spettroscopia Raman. Sui reperti sono state anche condotte indagini microbiologiche per verificare la presenza di biodeteriogeni.
I principali risultati possono essere così riassunti:
le analisi XRD mostrano che i campioni sono costituiti essenzialmente da leghe di ferro e alluminio e ossidi di ferro e rame, sovente con incrostazioni di quarzo e calcite,
le analisi XRF oltre a rivelare gli elementi maggiori quali Fe, Cu e Zn, rivelano per alcuni campioni tracce di Zn e Pb. Nello specifico, “Spec3” , la cui scheda museale riportava come composizione metallica 100% in ferro, è risultata essere una lega di Cu e Zn con tracce di Fe e Pb .Nessun biodeteriogeno risulta essere presente sugli oggetti analizzati.
Fine ultimo della ricerca consisterà nell’identificazione e pianificazione di successivi interventi green di risanamento e consolidamento
Mineralogical Characterization of Zoned Sphalerite from the Zn-Pb Ore Deposit of Longobucco (Sila Massif, Calabria, Southern Italy)
No full textPolymetallic ore deposits of the Sila Massif were subjected to raw metals exploitation starting from the Bronze and Iron ages. In spite of this, the scientific literature on their mineralogical characterization is not comprehensive and mostly out-of-date, as recently reported (Fregola et al., 2023). A mineral chemistry study with special focus on some phases could certainly contribute to decipher the origin of these mineral deposits. In this contribution, we present a mineralogical characterization of zoned sphalerite samples collected from the mineralized bodies outcropping along a fault zone cross-cutting monzodiorites at the “Torrente La Manna” site in the Longobucco area (Sila Massif, Calabria). In a separate contribution, we also present results on the whole mineralogical association of this mineralized site, including paragenetic considerations (Ciccolella et al., 2023; Session P.74). Sphalerite from Longobucco has been analysed by optical microscopy, micro-Raman spectroscopy, scanning electron microscopy (SEM), electron probe micro analyses (EPMA), and single crystal X-ray diffraction. Chemical micro-analyses revealed that sphalerite contains minor to trace amounts of Fe (0.803±0.021 to 9.550±0.064 wt%), Cd (up to 0.685±0.020 wt%), Hg (0.176±0.033 to 0.461±0.039 wt%), Cu (up to 0.454±0.011 wt%), and Co (up to 0.023±0.005 wt%). Sphalerite from Longobucco systematically shows colour and chemical zoning, with darker coloured growth bands due to enriched Fe-content. Sector zoning of Cd is also observed. The optical and paragenetic study allowed us to associate the different colour zones to different growth episodes. In particular, sphalerite of the first generation (sphalerite-I) is lighter coloured and Fe-poorer, with respect to the darker and Fe-richer one of the second generation (sphalerite-II). Micro-Raman spectroscopy and single crystal X-ray diffraction were performed on the different colour zones. In particular, Raman spectra show that number, position and relative intensity of the bands in the spectral range 250-400 cm-1 are related to the colour zoning and Fe-content of the sphalerite growth bands. These results are in good agreement with the previous literature (Buzatu et al., 2013). Preliminary single crystal X-ray diffraction data detected a slight difference between the lattice parameters of the lighter sphalerite-I (5.4140 ± 0.0009 Å) and of the darker sphalerite-II (5.4194 ± 0.0007 Å). Based on the relationship between Fe-content and cell parameters found in synthetic FexZn(1-x)S solid solutions (Osadchii & Gorbaty, 2010), our results would correspond to a difference from 0.06 to 0.15 mole fraction of FeS. Zoned sphalerite indicates a variation in the composition of the mineralizing fluid(s) during the geological history of the Longobucco ore deposit.
Buzatu A., Buzgar N., Damian G., Vasilache V. & Apopei A.I. (2013) – The determination of the Fe content in natural sphalerites by means of Raman spectroscopy. Vibrational Spectroscopy 68, 220-224. https://doi.org/10.1016/j.vibspec.2013.08.007
Ciccolella A., Fregola R.A., Ruggieri G., Tursi F., Festa V., Ventruti G. & Schingaro E. (2023) - Polymetallic mineral deposits of the Sila Massif (Calabria, southern Italy): The case study of Longobucco. Congresso SGI-SIMP, “The Geoscience paradigm: Resources, Risks and future perspectives”. Potenza, 19-21 sept. 2023, Abstract Book, p. .
Fregola, R.A., Ciccolella, A., Festa, V., Ruggieri, G., Schingaro, E., Tursi, F., & Ventruti, G. (2023) - Review of Polymetallic Mineralization in the Sila and Serre Massifs (Calabria, Southern Italy). Minerals, 13(3), 439. https://doi.org/10.3390/min13030439
Osadchii E.G. & Gorbaty Y.E. (2010) - Raman spectra and unit cell parameters of sphalerite solid solutions (FexZn1-xS). Geochim. Cosmochim Acta, 74, 568-573. https://doi.org/10.1016/j.gca.2009.10.02
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