Abstract - Vol LXXIX, April 2010 n. 1

- Ejected rocks from the 1872 eruption of Vesuvius, Italy: a petrographic and mineralogical overview.

- A set of 30 ejecta from the 1872 eruption of Vesuvius have been selected in the Scacchi’s collection of the Real Mineralogical Museum of University Federico II (Naples) to study their petrographic and mineralogical features and to provide insight into their genetic processes. Petrographic study has established the occurrence of four varieties: 1) homogenous lavas (hl); 2) composite lavas (Cl); 3) lavas and/or metamorphic rocks macroscopically conglomerate-like (lmC); 4) conglomerates (C). Mineral chemistry investigation has shown that the samples investigated consist of a large number of phases. These include minerals which typically occur in the Somma-Vesuvius lavas, like clinopyroxene, leucite (and other feldspathoids), plagioclase, K-feldspar and trioctahedral mica. Moreover a number of late to post-magmatic phases also occur. Textural, petrographic and mineral chemistry evidences indicate that phase crystallization are the result of a number of processes and complex interactions between rising lava, lava protholits and pulse of hydrothermal fluids and fumaroles at variable temperature and composition.

- Petrogenesis of the High-Alumina Basalt-Andesite suite from Sant’Antioco Island, SW Sardinia, Italy.

- Present-day Sant’Antioco Island (SW-Sardinia, Italy) hosted one of the southernmost, and youngest, subduction-related, Cenozoic magmatic events of western Sardinia. A high-alumina basalt-andesite rock association, the focus of this paper, crops out in the southern portion of the island and represents the mafic end-member of volcanism developed during Miocene. Basaltic andesites and andesites are the dominant rock-types, while basalts and dacites are occasional. Minero-petrographic and geochemical characteristics reveal: i) a clear calc-alkaline signature for these rocks, in spite of high FeO*/MgO ratios that mimic a tholeiitic affinity; ii) a magma evolution mainly controlled by fractional crystallization and iii) some degree of crustal assimilation. Phase relationships and compositions, mass balance calculations and T, P, X_H2O estimates consistently indicate that fractional crystallization occurred at low pressure (P=100-400 MPa), under different P_H2O conditions, which explain the observed wide shifts in major oxides (e.g., Al₂O₃ and MgO), for comparable sio2 contents, and the ambiguous tholeiitic character as well. Phase relationships in the least evolved lithotypes point out that higher H₂O concentrations (estimated at up to 6 wt%) in the melts reduced the crystallization of plagioclase and favoured that of olivine, whereas lower H₂O contents (up to 3 wt%) promoted plagioclase fractionation and earlier crystallization of orthopyroxene at the expense of olivine. this X_H2O imprint was recorded up to the most evolved compositions. Finally, the study rock suite can be derived from a parental (near-primary) magma matching in composition high-MgO basalts from the Montresta calc-alkaline district in nW sardinia, in the light of the close compositional similarity between the high-Al₂O₃ basaltic andesites in the two districts. thus, starting from a common parental composition, here we reconstruct liquid lines of descent, where the relative proportions of fractionating plagioclase vs mafic phases, as controlled by X_H2O in the melts, may account for the compositional differences of Sant’Antioco rock-types ab initio.

- Western production of “Ionian cups of type B2”: a preliminary archaeometric study to identify workshops in eastern Sicily.

- This work focuses on the petro-chemical characterisation of Ionian cups of type B2, a ceramic class that was widespread in the Mediterranean during the Archaic period. These cups were manufactured initially in eastern areas of Greece and then became extensively used also in the western Greek colonies, where they were produced until the early fifth century B.C. This contribution represents a first attempt to identify workshops in eastern Sicily. With this aim, Ionian cup fragments from five archaeological sites in eastern Sicily (Mendolito, Monte Castellaccio, Poira- Poggio Cocola, Piano Casazzi, Francavilla di Sicilia) were studied petrographically and geochemically. The resulting data were also compared with ceramic materials that can be identified as indigenous artefacts at each study site, as well as with the presently scanty literature data on Ionian cups from the Greek colonies of eastern Sicily. The results allow us to make some significant observations on the production areas of the studied sherds. Specifically, the Ionian cups from the above archaeological sites are quite different from the indigenous pottery, while both the petrographic and geochemical features of all the Ionian cups indicate a single production site, probably in a still unidentified colony of eastern Sicily. Alternatively, compositional homogeneity may indicate different but extremely specialised production, with the use of similar raw materials and techniques. This uniform production, although similar from a petrographic point of view to that previously identified in the Messina area, is distinguishable for its particular chemical signature.

- SEM-XRD investigation of deterioration morphologies and consolidation prior to restoration: the case of Porta Nuova in Ravenna (Italy).

- Porta Nuova in Ravenna (Northern Italy), built in the XVI century, has been the object of an interdisciplinary study, comprising an architectural survey of the Gate, mapping ashlars stones and drawing thematic maps. the following ornamental stones have been identified: Pietra d’Istria, Rosso Ammonitico Veronese, Marmor Proconnesium, Marmor Troadense, Pietra di Prun and Trachite dei Colli Euganei. Among these, Marmor Proconnesium and Marmor Troadense could be ancient materials recovered from monuments of Roman age. In order to carry out conservative restoration, it is of primary importance to know not only the nature and provenance of ornamental stones and building materials for possible replacement and/or integration, but also to define accurately their deterioration morphologies. The in situ analysis, implemented by mineralogical-petrographic analysis, SEM-EDS and XRD investigations, allowed drawing a map of the main types of deterioration morphologies, i.e. differential deterioration, black crusts, oxalate films, rust spots, fracture systems, biological patina and presence of vegetation (NORMA UNI 11182 - 2006). Moreover, the enhanced deterioration of the architectonic structure of the Gate has required specific investigation by microseismicity, endoscopic tests and georadar analyses. These results allowed to make a preliminary intervention with consolidation of fractured and detached stone elements, and to secure the building elements prior to the restoration intervention.

- Natural zeolites and white wines from Campania region (Southern Italy): a new contribution for solving some oenological problems.

- The purpose of this research is to provide a new mixture of Campanian zeolitized tuffs for solving two specific problems in the production of white wines: the protein and tartaric stability. In fact, a very frequent cause of turbidity and formation of organic deposits in white wines is the occurrence of thermolabile and thermostable proteins colloidal suspensions which precipitate in time, especially in summertime and during the storage and transport. Normally, to mitigate this risk wine producers use organic and inorganic stabilizers and clarifiers. The best known treatment, recognized also by the international Organisation of Vine and Wine (OIV) foresees the use of bentonite with a montmorillonite content not lower than 80%. The present paper aims at evaluating the use of two high zeolite grade Italian volcanoclastites such as the Neapolitan Yellow Tuff (NYT) and the Yellow Facies of the Campanian Ignimbrite (YFCI), in the treatment of three peculiar white wines of the Campanian region (Southern Italy): Falanghina, Fiano di Avellino and Greco di Tufo. Granulates were produced starting from tuff blocks as provided by quarries. Some grain size fractions have been prepared to investigate the zeolite content phillipsite + chabazite + analcime) by X-ray diffraction (XRD). A 2-5 mm grain size fraction was chosen for NYT and a 5-10 mm for YFCI. Three Campanian monocultivar white wines were used for the test: the Falanghina 2006 vintage, the Fiano di Avellino DOCG 2007 vintage, and the Greco di Tufo DOCG 2008 vintage. 48 samples with mixture of the zeolitized tuffs, 1 sample with mixture of a synthetic zeolite a and 1 sample with mixture of a commercial sodium activated bentonite were prepared. ICP-OES analysis for the determination of ECEC, Ion Chromatography (IC) analyses for the determination of some major cations and Turbidimetric tests for the definition of the protein stabilization process before and after treatments were also carried out. It was evidenced that high zeolitized tuff/wine ratios enable the protein stabilization whereas a significant decrease of potassium ion after the treatment with a zeolite-rich powder improves the tartaric stability, a serious problem in all the wine productions. The results of these tests refer to a laboratory scale research. A transfer of the experiment to a pilot plant scale is in progress.

- Lead-antimony sulfosalts from Tuscany (Italy). X. Dadsonite from the Buca della Vena mine and Bi-rich izoklakeite from the Seravezza marble quarries.

- Two very rare Pb sulfosalts, dadsonite and izoklakeite, discovered in the Apuan Alps, represent the first italian occurrence and were characterized by electron probe microanalysis and X-ray diffraction. Dadsonite from the Buca della Vena Ba-Fe deposit (two samples) has formula Pb_22.64Sb_24.90S₆₀Cl_1.12 and (Pb_22.90Cu_0.01)Sb_25.12S₆₀Cl_1.07, in fair agreement with the ideal formula Pb₂₃Sb₂₅S₆₀Cl. XRPD gives the monoclinic unit cell a 19.058(3), b 8.234(2), c 17.352(3) Å, ß 96.33(2)°. Dadsonite, with both pillaite and pellouxite, is the third chlorosulfosalt from Buca della Vena, that reveals a high chlorinity of mineralizing solutions. Izoklakeite from Seravezza has the mean composition (wt.%) Pb 45.69, Bi 24.89, Sb 8.16, Cu 1.08, Ag 0.74, Hg 0.29, S 15.43, Se 2.86, sum 99.14, with structural formula Cu_1.92[Ag_0.77Hg_0.16Pb_24.49(Bi_13.23Sb_7.44)_∑=20.67]_∑=46.09(s53.43 se4.02)_∑=57.45.It is a Bi-rich izoklakeite, close to the ideal Fe- and ag-free formula, Cu₂Pb₂₆(Bi,Sb)₂₀S₅₇. Significant Se and Hg contents constitute chemical peculiarities of this occurrence. XRPD gives the orthorhombic unit cell a 34.272(4), b 38.351(5), c 4.098(1) Å.