1,721,010 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 textLacalamita, 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 textFluorophlogopite 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
Kinetics of Fe-oxydation/deprotonation process in Fe-rich phlogopite under isothermal conditions
No full textThe kinetics of the Fe-oxidation/deprotonation process in a natural Fe-rich phlogopite from Mt.
Vulture (Potenza, Italy) was studied under isothermal conditions by in situ high-temperature singlecrystal
X-ray diffraction. Isothermal annealing experiments were performed at five temperatures in
the range 640–750 °C on five crystals with similar chemical composition and lattice parameters. The
Fe-oxidation/deprotonation process at high temperature occurs with a reduction of unit-cell parameters
and cell volume. The changes in unit-cell parameters measured at high temperature and during cooling
show that the same degree of Fe-oxidation/deprotonation process was achieved at all temperatures.
Changes in unit-cell parameters with temperature and time show that the kinetics of Fe-oxidation/
deprotonation in phlogopite follows an exponential law, and the temperature dependence follows the
Arrhenius relation. A kinetic analysis was performed and good agreement was obtained with the onedimensional
diffusion model. An apparent activation energy of 195(4) kJ/mol was determined
Time evolution of Fe-oxydation/deprotonation process in Fe-rich phlogopite under isothermal conditions
No full textCrystal-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
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
CHEMICAL AND STRUCTURAL STUDY OF 1M- AND 2M1-PHLOGOPITES COEXISTING IN THE SAME KASENYI KAMAFUGITIC ROCK (SW UGANDA)
No full textAbstract In the present work, crystal chemical variations
between 1M and 2M1 phlogopites coexisting in the same rock sample from kamafugite of Kasenyi
(southwest Uganda, west branch of the East African Rift) were explored by electron probe
microanalyses, single crystal X-ray diffraction and Mo ̈ ssbauer spectroscopy. Chemical analyses
revealed close similarity both within and between the two polytypic arrangements as well as
high TiO2 (*4.9 wt%) and Al2O3 (*12.9 wt%), and low Cr2O3 (*0.8 wt%), F (*0.3 wt%) and BaO
(*0.2 wt%) con- tents. Room temperature 57Fe Mo ̈ ssbauer investigation proved that the studied
mica is a tetraferriphlogopite with: IVFe3? = 19(1) %, VIFe2? = 58(1) %, VIFe3? = 23(1) %.
Single crystal refinement showed that both polytypes have narrow range of variation in terms of
some relevant unit cell parameters and similar values in terms of mean bond lengths, mean atomic
numbers and distortion parameters. Similar substitutions were active in the structure of the
1M and 2M1 studied phlogopites. However, in 2M1 poly- types the oxy-type substitutions were found
to occur to a greater extent. Comparison of unit layer of 1M mica (in the
2M1 setting) with that of the 2M1 ones showed that the 2M1 polytypes are affected to different
extent by relative shifts of the upper and lower triads of octahedral oxygens along the ±b
directions. This effect did not cause any symmetry
lowering in the T-O-T layer of the studied samples
- …
