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Wingellina is a large Ni-Co laterite deposit, located in Western Australia. The laterite pro le formed from the weathering of the Mesoproterozoic ma c and ultrama c intrusions of the Giles Complex, mainly consisting of peridotite and gabbro. The exploitable Ni-Co resources of the deposit are represented by Ni-Co-bearing Fe/ Mn-oxy-hydroxides mostly occurring in the more sur cial limonite horizon (probable Reserve = 168 Mt @ 0.98% Ni and 0.08% Co). This makes the Wingellina deposit an unusual “oxide-type” laterite. The deeper saprolite horizon has a lower tonnage, but contains higher Ni concentrations (up to ~3 wt%). We have studied the mineralogy of the Ni-phyllosilicates from saprolite samples of the Wingellina deposit collected from two different pro les, overlying a gabbro and a serpentinite (former peridotite) bedrock, respectively. From mineralogical and petrographic analyses, we determined that the initial alteration stage of the gabbro was characterized by the formation of nontronite and montmorillonite, at the expenses of olivine and pyroxene, respectively. The congruent dissolution of plagioclase played an important role, supplying the Al required for montmorillonite formation. The following stage was represented by the alteration of montmorillonite, resulting in the precipitation of kaolinite. This paragenetic sequence is in agreement with a typical lateritization pathway. The alteration of the serpentinite followed instead a multistage route. During the initial lateritization stage, the original serpentine was altered to a Ni-rich srp II, as well as to tri- and dioctahedral smectites (saponite and nontronite). The chemistry of smectites suggests that the saponite-to-nontronite conversion developed through a progressive increase of the Fe content within trioctahedral smectite. In a following stage, in the upper section of the serpentinite-derived saprolite, disordered talc-smectite and chlorite-smectite interstrati ed clays formed at the expenses of the former serpentines and smectites. This process is not typical of humid lateritic environments, but common under arid climates characterized by circulation of saline and alkaline uids. In the Wingellina area, the onset of arid climate during the Late Miocene-Pliocene (Anand and Paine, 2002) likely promoted the formation of these interstrati ed clays. Taking into the nature and the late stage formation of disordered interstrati ed clays in the Wingellina saprolite, the evaporative-driven clays authigenesis can be considered as a counterpart of the per descensum process that explains the garnierite formation in active margins.

Karst collapse sinkholes (KCS) are a peculiar karst morphology resulting from the collapse of the topographic surface caused by subsurface karstification. In Southern Apennine these phenomena are not randomly distributed but concentrate in several zones, named High Sinkhole Concentration Areas (HSCA), showing peculiar geological, structural and hydrogeological conditions. Gas vents and mineral springs are spread out in these HSCA, and are often stricty related to the KCS. Starting from four representative areas, the aim of this study is to ascertain if there is a genetic link between peculiar mineralogical vs. geochemical features of densely fractured/altered rocky masses in KCS, gas vents/springs occurrences and diffuse hypogenic karstification. By means of a multidisciplinar approach (geological/geomorphological, mineralogical and geochemical) we selected and analysed four different kind of samples related to KCS, gas vent and spring occurrences: i) altered to deeply altered limestones sampled in the sinkholes, ii) unaltered limestones sampled in close proximity to sinkhole areas, iii) gypsum‐rich crusts/patinae, precipitated near to gas vents, iv) gypsum‐ and calcite‐rich precipitates occurring at springs or inside caves. Among neoformed non‐carbonate minerals, gypsum is virtually ubiquitous, halides (fluorite, halite, sylvite) also occur in small to trace amounts. The mineralogical assemblages of the different samples show similarities and may be also compatible with hypogenic speleogenesis and with a process of alteration of the carbonate bedrock by means of uprising mineralizing fluids along structural discontinuities. Stable isotopic compositions (S, O) display a strong variability in δ34S and δ18O for sulfate in the different areas, but a deep‐seated sulfur source can be hypothesized for many of the studied KCS‐related samples. This study has important implications for the relationships between areas of high concentration of sinkholes, regional fault systems, mechanical characteristics of rocks and the high seismicity typical of these areas of the Southern Apennines.

A Roman luxury villa (1st century BC) was discovered in the town of Positano, in the Sorrento peninsula (Campania region, southern Italy). Despite being more than 20 km away from Vesuvius, the villa was buried under almost overall 20 meters (total thickness) of pyclastic materials of the Plinian eruption of 79 AD, which destroyed Pompeii and Herculaneum towns. The exceptional level of conservation of this residential complex is due to the peculiar burial process, which determined the excellent state of preservation of both the fresco decorations (Fourth Style) and all other artefacts (masonries, plasters, tiles, furnishing remains, wooden elements, kitchenware, glazed oil lamps, bronze vessels and other metallic findings, etc.). This study presents the results of a multi-analytical archaeometric analysis of plasters, fresco pigments and roof tiles, aimed at identifying their mineralogical and petrographic nature and the provenance of raw materials. Constraints to the geoarchaeological landscape of the Positano area are also given. The analyzed plasters are mainly lime-based, usually with the addition of an aggregate. The anchoring layer is made by a volcanic component, characterized by clinopyroxene, alkali feldspar, garnet, amphibole, biotite and leucite crystals, together with a sedimentary component represented by carbonatic fragments, also with traces of microfossils. The features of plasters confirm the high degree of technological standardization of plasters in classical Roman age. Mineral pigments recognized by preliminary XRD are mainly iron-based for the ochers-red-crimson colors and copper-based for green-blues colors. In the roof tiles two kind of tempers are identified. In three samples a volcanic temper was identified, and represented by clinopyroxene, feldspar, garnet and leucite, whereas the temper of a fourth sample contained pumices with minor amounts of alkali feldspar, clinopyroxene and biotite. The raw materials are of local provenance (Somma-Vesuvius, Phlegraean Fields, Apennine limestones), and the microstructure of the materials are comparable with similar artefacts from Pompeii, Herculaneum and other Roman sites in Campania region. On the basis of geoarchaeological investigations, here reported, it is reasonable to think that there are other unearthed archaeological areas in Positano that will require further study to be properly known

Sodalites and sulfatic sodalites in holocrystalline K-feldspar-rich ejecta from the SommaVesuvius 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 P4¯3n 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.