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Abstrae~Clinoptilolite and mordenite occur as diagenetic products of medium-grained, moderately welded and poorly sorted pyroclastic flows belonging to the Tertiary calc-alkaline volcanism of Sardinia. Both clinoptilolite and mordenite occur within pyroclastic flows of the same stratigraphic unit. Mordenite frequently occurs in the late volcanic sequences from Anglona area (northern Sardinia). Textural features indicate that zeolites are products of glass alteration. Thin sections show either complete alteration of glassy shards by clinoptilolite and mordenite or unaltered shards with clinoptilolite or mordenite confined to the cineritic matrix. During the zeolitization process, interacting fluids were important in the mobilization and distribution of alkali elements. The compositional variations of clinoptilolite and mordenite within a single sample showed trends that suggest steps in a continuous process probably evolving towards equilibrium conditions.

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Sodalites and sulfatic sodalites in holocrystalline K-feldspar-rich ejecta from the Somma Vesuvius volcanic complex, Italy, have been characterized by combined chemical, structural and spectroscopic analyses. Sodalite has a relatively homogeneous chemical composition, with the ubiquitous presence of CO32– and H2O/OH–. The sulfatic sodalites are isomorphous and have cage structures which can contain a wide variety of anions, molecular species and cations. Molecular CO2 and H2O/OH– are present in sulfatic sodalites, instead of the CO32– anions that are present in sodalite sensu stricto. The cell dimensions of the all of the studied sodalite samples are very similar, the sulfatic sodalite cell dimensions are more variable. Structure refinement of a distinctly green sample confirms the P3n space group. Metasomatic magma-derived fluids that are rich in H2O, CO2, Cl and S are believed to be responsible for the genesis of the relatively late-stage phases which form the ejecta containing the sodalite-group minerals.

This work is part of a project focused on the Somma–Vesuvius volcano and aimed at identifying Cu minerals related to mineralizing processes associated with magmatic activity in an active magmatic-hydrothermal system. A mineralogical survey was carried out on a set of samples represented by sublimates and fumarolic products from the collection of the Mineralogical Museum of the University of Naples Federico II (Italy). These samples are mainly related to most recent eruptive episodes of Vesuvius activity, from 1631 onward. Copper-bearing minerals were characterized, as well as associated minerals, by X-ray diffraction (XRD) scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). An investigation on the structural complexity of Cu-mineral assemblages with different temperature formations was also carried out using the TOPOS software package. The main copper phases are sulfates, followed by vanadates, hydroxyhalides, oxides, carbonates, silicates and finally, phosphates. New mineral occurrences for Vesuvius, both Cu-bearing and Cu-free, are described. Nevertheless, the fumarolic/alteration minerals at Vesuvius cannot be considered of economic relevance as a copper reservoir, this type of mineralizations are significant for copper crystal chemistry and for the knowledge of the mineralogical variants. The obtained datasets can be of interest for the knowledge of volcanic byproducts of copper ore deposits (i.e., porphyry copper systems) and of (base) metal segregation processes.

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