1,721,035 research outputs found
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 textMineralizations of the Sila Massif (Calabria, southern Italy): The case study of the Zn-Pb ore deposit of Longobucco
No full textAlthough the mineral deposits of the Longobucco area in the Sila Massif (Calabria, southern Italy) are historically known as metal exploitation sites since ancient times, scientific interest in their study has only recently been renewed (Fregola et al., 2023a). In particular, a detailed mineralogical characterization using modern methodologies and framed in an updated geological context, would help to decipher their genesis. We have collected samples of the mineralized bodies outcropping along a fault zone crosscutting monzodiorites at the “Torrente La Manna” site in the Longobucco area, where Vighi (1953) first observed a sphalerite-galena- pyrite-quartz-calcite mineral association. We have characterized such minerals using optical microscopy, scanning electron microscopy (SEM), electron probe microanalyses (EPMA), and micro-Raman spectroscopy. Sphalerite is the dominant polymetallic mineral, showing color and chemical zoning, and can be used as fingerprint to differentiate the evolution stages of the mineralized deposit; noteworthy its mineralogical characterization is presented in a separate contribution to this congress (Fregola et al., 2023b; session P.40). Our reconstructed paragenetic sequence comprises almost five growth stages. Early minerals include a light- colored Fe-poor sphalerite-I, followed by a darker Fe-richer sphalerite-II formed in association to euhedral quartz-I crystals. The latter show color and chemical zoning of Al, Na, K, Ca. Moreover, we have observed a Mn-rich (1.19±0.03 to 0.49±0.02 wt%) and Mg-poor (up to 0.08±0.01 wt%) calcite, partly hosting REE- fluorcarbonates. The latter minerals are reported here for the first time in the Longobucco area, and consist of synchysite, with 20 to 60 μm grain size, and total REE (Ce, La, Y, Nd, Sm, Pr, Gd, Dy) concentrations ranging between 42.64 and 2.40 wt%. Late stages minerals comprise sphalerite-III, quartz-II, pyrite, and Ag- free galena with low Sb-content (up to 0.09±0.03 wt%).
Fregola, R.A., Ciccolella, A., Festa, V., Ruggieri, G., Schingaro, E., Tursi, F., & Ventruti, G. (2023a) - Review of Polymetallic Mineralization in the Sila and Serre Massifs (Calabria, Southern Italy). Minerals, 13(3), 439. https://doi.org/10.3390/min13030439
Fregola R.A., Ciccolella A., Ruggieri G., Ventruti G., Mesto E. & Schingaro E. (2023b) – Mineralogical characterization of zoned sphalerite from polymetallic mineralization of the Sila Massif (Calabria, Southern Italy): The Longobucco case study. Congresso SGI-SIMP, “The Geoscience paradigm: Resources, Risks and future perspectives”. Potenza, 19-21 sept. 2023, Abstract Book, p. .
Vighi L. (1953) Sulla geologia e sulle mineralizzazioni metallifere della regione di Longobucco in Calabria. Mem. e Note Ist. Geol. Appl. Napoli, 5, 3–61
Cristallochimica e significato petrogenetico dei granati titaniferi del complesso alcalino-carbonatitico di Tapira (Brasile).
No full textPlinius (supplemento italiano all¿European Journal of Mineralogy
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
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
Crystal-chemistry of micas belonging to the yangzhumingite-fluorophlogopite and phlogopite-fluorophlogopite series from the Apuan Alps (northern Tuscany, Italy)
No full textThe present work reports the crystal-chemical characterization of micas from the Monte Arsiccio and Buca della Vena mines (Apuan Alps, Italy) through electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy. The sample from the Monte Arsiccio mine can be classifiedas an intermediate member of the yangzhumingite-fluorophlogopite series, with average crystal-chemical formula (K0.85Na0.01Ba0.09)Σ=0.95(Mg2.11Fe2+0.23Fe3+0.11Cr3+0.01Al0.20Ti0.04☐0.30)Σ=3.00(Si3.20Al0.80)Σ=4.00O10.00F1.90Cl0.02(OH)0.08. Unit-cell parameters are a ~ 5.30, b ~ 9.18, c ~ 10.14 Å, β ~ 100.12°, V ~ 486.22 Å3, corresponding to the 1M polytype. Structure refinements, performed in C2/m space group, converged to R1 = 3.54 and 4.46% and provided Mg plus Fe occupancy in the range 86–94% for the octahedral M1 and M2 sites. Raman spectroscopy shows very weak bands in the OH stretching region at ~ 3690 and 3580 cm−1. The sample from the Buca della Vena mine has been identified as an (OH)-rich fluorophlogopite, with average crystal-chemical formula (K0.84Na0.02Ca0.01)Σ=0.87(Mg2.12Fe2+0.55Fe3+0.10Al0.18☐0.05)Σ=3.00(Si2.99Al1.01)Σ=4.00O10.00F1.02Cl0.09(OH)0.89. Its unit-cell parameters are a ~ 5.33, b ~ 9.22, c ~ 10.23 Å, β ~ 100.09°, V ~ 494.39 Å3. Structure refinements gave good R1 values (3.27 and 4.37%) and revealed octahedral occupancy of 82–84% Mg and 16–18% Fe. Strong Raman signals at ~ 3702 cm−1 and 3595 cm−1 were observed in the OH stretching region. The findings allow to better understand not only the mineralogy of the Apuan Alps but, more generally, the crystal chemical details of intermediate dioctahedral-trioctahedral mica belonging to the yanzhumingite-fluorophlogopite series
A survey on (Na, H3O+, K)Fe3O(SO4)6. nH2O compounds: architectural principles and influence of the Na-K ionic replacement on their structures
No full text
Morphological and mineralogical characterization of surficial weathering on calcarenite rocks in the rupestrian system of ?San Michele delle Grotte? at Gravina in Puglia (Bari, Apulia)
No full textSan Michele delle Grotte is a rupestrian cave excavated into the "Calcarenite di Gravina" formation, resting over the Cretaceous formation of "Calcare di Altamura". Both rock types show evident instability features and intense surficial rock weathering. A detailed mineralogical and morphologic characterization of Calcarenite di Gravina Fm. samples has been carried out by means of optical and petrographic microscope (OM and PM), scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD). In thin section, bioclastic packstone to grainstone fabrics were observed. In the surficial portion of the rock it is possible to find biological colonizations and efflorescences: the first are dominated by algae covering the calcite substrate, whilst the efflorescences contain mainly sulfates such as syngenite, gypsum and arcanite, and other salts including niter and sylvine. A distinctive enhance of microporosity on the rock surface immediately at the contact with the biological colonizations and efflorescences was observed. A high abundance of biological colonizations was found where the hostrock is well exposed to light, whereas efflorescences prevail in the innermost parts of the cavity. Efflorescences may originate from both anthropogenic air pollution (wet and dry airborne deposition that provides sulfate and nitrate anions) and circulation of soil water whose composition can be modified, for instance, by fertilizers. Analysis of the weathering conditions of calcarenite rocks is a crucial factor in determining the likely possibility of failures and collapses in underground environments
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