Formation of kaolinite-smectite (K-S) mixed layers in a soil toposequence developed from basaltic parent material was examined. The soil formed in a temperate climate with alternating dry and wet seasons in Sardinia (Italy). Chemical composition and charge characteristics of the smectite component in the K-S mixed layers were analyzed to help determine a mechanism for formation. Soils were sampled at the top, intermediate, and base of a steep (35%) slope. As indicated by X-ray diffraction data, the fine clay fraction (>0.1 μm) in the soils is dominated by K-S with a decreasing proportion of kaolinite from the top (70%) to the base (30%). Rapid internal drainage induced by the slope is probably the major factor responsible for the formation of K-S. Chemical composition and charge characteristics of the smectite component in the K-S were analyzed by X-ray diffraction (intercalation with alkylammonium ions), cation exchanged capacity (CEC) and surface area measurements, and infrared spectroscopy. Results indicate that the smectite component is nearly identical over the soil toposequence. The smectite component is the same with respect to charge magnitude and chemical composition, independent of the proportion of kaolinite and smectite components. This suggests the pedogenic formation of K-S by transformation of smectite through dissolution of some smectite layers and subsequent crystallization of kaolinite between the layers of the remaining smectite crystallites.

The Mediterranean flora is characterized by a high number of narrow endemic plant species that are often restricted to a few small populations. One of these species, Valeriana amazonum, a perennial plant occurring only in the Supramontes region of central eastern Sardinia, is categorized as Critically Endangered on the IUCN Red List because of its restricted range, small population size and an inferred decline caused by several threats. During 2007–2022, we monitored all mature individuals of this plant annually and surveyed ecologically suitable sites for the species. We identified two previously unknown populations and also learnt of two successful translocations carried out independently by an unknown local citizen. As our monitoring data indicate there has been no decline in the number of mature individuals over the period of monitoring, the species’ conservation status requires reassessment. We recommend that V. amazonum should be recategorized as Near Threatened as it seems to be poorly known rather than highly threatened. This could also be the case with other narrow Mediterranean endemics, especially those that grow in inaccessible habitats for which long-term studies are needed to assess conservation status.

Clinoptilolite-rich materials from widespread pyroclastic and epiclastic deposits of northern Sardinia were investigated to assess their cation exchange properties and to find the most reliable experimental method to determine their cation exchange capacity (CEC). The CECs were evaluated using a cross exchange method (CEM) and a batch exchange method (BEM). The CEM resulted in values 30–35% lower than the theoretical or expected CEC calculated from the chemical analyses of the clinoptilolite-rich materials. The BEM resulted in CECs 6–12% lower than the expected CECs. Various parameters, such as the grain-size of powders (<64 µm and 125–250 µm) and replacement cation (Na+, K+, Li+, Cs+, NH4+, Ca2+, Mg2+, Sr2+) were evaluated in order to optimize the cation exchange process, i.e. enhance complete exchange. The particle size did not affect the exchange process appreciably. The type of replacement cation had a substantial effect on the experimental CEC determined by the BEM. The NH4+ and Cs+ replacement solutions resulted in the best experimental CECs ranging between 75% and 94% of the theoretical CEC with NH4+ as the replacement cation and 79% and 88% of the theoretical CEC with Cs+ as the replacement cation. The exchange efficiency was also measured as a function of ammonium concentration in the replacement solution (0.50, 1.00, 2.00 and 3.00 M). Experimental CECs ranged between 94% (0.5 M NH4Cl solution) and 99% (1 M NH4Cl solution) of the theoretical CEC for one epiclastic rock sample and between 79% (3 M NH4Cl solution) and 87% (2 M NH4Cl solution) of the theoretical CEC for one pyroclastic rock sample.

Clay minerals from soils of a red-black soil complex developed from basaltic parent material in Sardinia are formed along a short toposequence (200 m). At the foot of the sequence, a clay-rich, black Vertisol forms, whereas at the summit, the soil is a dark reddish-brown Inceptisol. X-ray diffraction, infrared spectroscopy (FTIR), cation exchange capacity (CEC) and permanent and variable charges analyses were used, and the data show that clay minerals varied according to soil horizon and topographic position of the soil. Clay minerals in the Inceptisol are dominated by kaolinite and mixed-layer kaolinitesmectite (K-S, K:S >0.5), whereas the Vertisol contains smectites and K-S with K:S proportions <0.5. In the Vertisol, the proportion of kaolinitic layers in the K-S increases from the C horizon (K:S ∼0.35–0.40) to the Ap horizon (K:S ∼0.40–0.45). This soil clay-mineral distribution, in relation to topography, is similar to that reported for other (kaolinitic) red-black (smectitic) soil associations in subtropical and tropical areas. The sequence forms by downward drainage on summits and slopes, and buildup of ions in ‘lows’ produces smectites. Fourier transform infrared spectra indicate that two types of smectite are formed in the C horizon of the Vertisol; one is more ferric (Fe-beidellite, nontronite), the other more aluminous. Mineralogical evolution in the soil profile (from C to Ap horizon) shows a decreasing proportion of ferric smectite layers (compared to the more aluminous smectite layers). This would indicate that ferric smectite layers are preferentially transformed (or dissolved) to give kaolinite layers, with Fe precipitating as oxides and/or oxy-hydroxides or retained partly in kaolinite layers. Because the surface properties of clay minerals are related to mineralogy, the CEC (33–41 cmol kg−1) in the brown Inceptisol is ∼50% pH-dependent charge while in the Vertisol up to ∼75% of the CEC (48–61 cmol kg−1) comes from accessible permanent charges.

The thermal behavior of two clinoptilolites from an epiclastic and a pyroclastic deposit of central-northern Sardinia and of their exchanged forms (Li, Na, K, Cs, Mg, Ca, Sr and ammonium) were investigated by differential thermal analysis and thermogravimetry up to 1000°C. Their thermal stability was studied by evaluating the residual crystallinity (expressed as rehydration capacity) after 2 h thermal treatments at 450, 600 and 900°C. The water loss at 1000°C was linearly related to the radius (r) and the charge (z) of the exchangeable cations by the equations r2/z or r3/z, which are proportional to the inverse of the charge density over the surface or to the charge density over the volume of the cations.

The cation composition plays a crucial role in determining the thermal behavior of clinoptilolite. The presence of cations such as Cs or K, which have low surface or volume charge densities, was found to increase the thermal resistance. In particular, the crystallinity of Cs- and K-exchanged forms of both clinoptilolites was not affected by thermal treatment at 450°C and was only slightly reduced by thermal treatment at 600°C.

Predicting the thermal behavior of natural and cation-exchanged forms of these clinoptilolites can provide useful information for possible applications in catalysis, in the case of high thermal stability, or for thermal transformation into ceramics or lightweight aggregates.

La Verge de Montserrat is a statue of the Virgin Mary and her son found in Catalonia in the eleventh century in which both characters are depicted as “Black.” This female figure occupies a particular position in current Catalonia since she is considered the patron saint of the country and constitutes one of the symbolic cornerstones of Catalan nationalism. Through the concept of “iconic path,” this article tracks the formation and evolution of this image in Catalonia from its inception until the present day, bringing special attention to the roles and significances that it has acquired within the context of the current pro-independence movement. We also draw a comparison between the “lives” of this image in Catalonia and its development in other countries, namely Puerto Rico, Equatorial Guinea and Sardinia. In each of these places, the image of the goddess has been reinterpreted according to local viewpoints. Yet these conceptualizations are not fixed or homogeneous, but radically dynamic and problematic. The iconic paths of images diverge and converge across time giving birth to new creative exercises. Through this approach, our aim is to propose a relational and processual model for the study of religious images, and images in general, as historical objects.

Field investigations into the sedimentary evolution of the Mulargia–Escalaplano late- to post-Variscan basin in Sardinia have been carried out. This basin is the only Variscan molassic basin in the Southern Variscan Realm where relationships between all the Late Pennsylvanian to Middle Triassic sedimentary cycles have been detailed for the first time. Here the interplay between tectonics and sedimentation can also be inferred. The investigations evidence that the sedimentary response recorded in the basin matches the progress and final collapse of the southern Variscan chain branch. The basin preserves continental deposits of decreasing energy organized in cycles, separated by weak unconformities related to abrupt volcano-tectonic climaxes and influenced by progressively drying climates. The sedimentary facies and stratigraphy suggest a progressive widening of the basin and decreasing depositional energy to the southeast as well as the migration of the basin depocentre in the same direction. Stratigraphic, environmental and evolutionary correlations between the presently separated NW and SE parts of the basin are reconstructed by considering the role of tectonics. As a result, a detailed lithostratigraphic framework for the Mulargia–Escalaplano basin is proposed. The findings in the sedimentary evolution match the evolution of similar coeval basins of France and Germany, following a pull-apart to extensional model. Based on comparisons with the other Sardinian and SW Europe coeval basins, relationships between ‘limnic’ and red bed successions in SW Europe during the collapse of the Variscan chain are discussed. The renaming of the European tectonomagmatic ‘Mid-Permian Episode’ to the ‘Lower Permian Episode’ is proposed.

The exceptional find of the tooth of a sperm whale (Physeter macrocephalus) at Monte d'Accoddi adds to the documentation on the possible presence, and exploitation by humans, of cetaceans in the prehistoric Mediterranean. The dating (3638–3378 BC) appears to make it the oldest cetacean find in Sardinia.

The island of Sardinia is well known for its Late Neolithic and Copper Age underground rock-cut tombs that were used over generations for collective burials. Many tombs were decorated to resemble house interiors and cemeteries are often referred to as villages of the dead. Research so far has focused on excavating stratigraphic contexts within some of these monuments, or on typological classifications of tomb plans and wall decorations, but the landscape context of the cemeteries and their relationship to settlements have been overlooked. The article presents the results of two seasons of survey in Ossi (north-west Sardinia), focusing on two major cemeteries (Mesu ‘e Montes and S’Adde ‘e Asile). Combining fieldwalking, mapping and 3D recording techniques, the survey provides a comprehensive documentation of the cemeteries (from the underground architecture of individual tombs to their landscape setting) and yields evidence of prehistoric settlements in their vicinity. The article discusses the topographic and visual relationships between the tombs and the residential areas and how they may reflect social interactions between the living and the dead in late prehistoric Sardinia.

The Posada–Asinara Line is a crustal-scale transpressive shear zone affecting the Variscan basement in northern Sardinia during Late Carboniferous time. We investigated a structural transect of the Posada–Asinara Line (Baronie) with the aid of geological mapping and structural analysis. N-verging F2 isoclinal folds with associated mylonitic foliation (S2) are the main deformation features developed during the Posada–Asinara Line activity (D2). The mineral assemblages and microstructures suggest that the Posada–Asinara Line was affected by a retrograde metamorphic path. This is also confirmed by quartz microstructures, where subgrain rotation recrystallization superimposes on grain boundary migration recrystallization. Crystallographic preferred orientation data, obtained using electron backscatter diffraction, allowed analysis of quartz slip systems and estimation of the deformation temperature, vorticity of flow and rheological parameters (flow stress and strain rate) during the Posada–Asinara Line activity. Quartz deformation temperatures of 400 ± 50 °C have been estimated along a transect perpendicular to the Posada–Asinara Line, in agreement with the syn-kinematic post-metamorphic peak mineral assemblages and the late microstructures of quartz. The D2 phase can be subdivided in two events: an early D2early phase, related to the metamorphic peak and low kinematic vorticity (pure shear dominated), and a late D2late phase characterized by a lower metamorphic grade and an increased kinematic vorticity (simple shear dominated). Palaeopiezometry and strain rate estimates associated with the D2late deformation event showed an intensity gradient increasing towards the core of the shear zone. The D2early deformation developed under peak temperature conditions, while the D2late event was active at shallower structural levels.

Excavation at nuraghe S'Urachi has yielded a wide range of archaeobotanical materials preserved through charring and waterlogging. This unusual evidence allows us to study the agricultural practices and diet of this community in the first millennium BC and to understand better the economic and cultural interactions between Sardinia and the wider Phoenician and Mediterranean world.

Hip hop, reggae/raggamuffin, and fusions between these genres, emerged in the Italian island of Sardinia in the 1980s and 1990s. In this article, we examine the ways in which these transnational music forms have found fertile terrain in post-colonial Sardinia across generations and cultures through the music of the historic hip hop crew, Sa Razza, the next generation ‘rappamuffin’ artist, Randagiu Sardu, and the Senegalese-Sardinian Afro-reggae musician, Momar Gaye. Through the analysis of selected tracks and video clips we explore how overlapping cultural, social, and political discourses of decolonisation are framed and narrated through language, music, and images as a means of expressing cultural and political agency, critiquing the impacts of exploitation and colonisation, and consciously and self-reflexively reinterpreting and celebrating marginality.

Late to post-Variscan sedimentary basins of Sardinia were influenced during Pennsylvanian to Permian times by two main tectono-sedimentary cycles: a Pennsylvanian to Cisuralian cycle represented mainly by dark limnic deposits, overlain by a Guadalupian to a possibly Lopingian cycle, mostly characterized by red-bed deposits. Lacustrine waterbodies developed in some sedimentary basins that were filled with siliciclastic to frequently early silicified carbonate deposits, depending on the climate and environmental conditions, landscape morphology and tectonic regime. The limnic successions of the lower tectono-sedimentary cycle were deposited in permanent, tens of metres deep lakes in deep, narrow tectonic strike-slip basins under a temperate to warm-humid climate. They started as lakes with terrigenous sedimentary input and developed minor carbonate deposits mainly at the end of their story. Conversely, the red-bed successions of the upper cycle were deposited in ephemeral, shallow playa lakes related to wider basins in an extensive alluvial plain under a hot and arid climate. Here, the siliciclastic sediments are intercalated with thin carbonate beds that are typical of a high evaporation rate. The evolution of the lake type could be related not only to a major climatic shift, but also to the changing morphotectonic conditions of the Variscan chain influencing the local microclimate. Comparisons with coeval successions in the Provence Basin, the Massif Central Aumance basin (France) and the Saar–Nahe Basin (Germany) show both similarities and differences between the basins.

The gullet worms, classical Gongylonema pulchrum and newly differentiated Gongylonema nepalensis, are prevalent in various mammals in Japan and Sardinia, Italy, respectively. The former species is cosmopolitan in distribution, dwelling in the mucosa of the upper digestive tract of a variety of domestic and wild mammals, and also humans. At present, the geographical distribution of G. nepalensis is known in Nepal and Sardinia, with the nematode having been recorded from the oesophagus of water buffaloes (Nepal), cattle, sheep, goats and wild mouflon (Sardinia). To clarify their natural transmission cycles among domestic and wild mammals, the present study analysed the ribosomal RNA gene (rDNA) and mitochondrial cytochrome c oxidase subunit 1 gene (cox1) of worms of various origins: G. pulchrum worms from sika deer, wild boars, Japanese macaques, and feral alien Reeves's muntjacs in Japan, and G. nepalensis worms from a red fox and a wild boar in Sardinia. Although the internal transcribed spacer (ITS) regions of rDNA and partial cox1 nucleotide sequences of G. pulchrum from native wild mammals in Japan were distinct from those of the worms in cattle, the worms from feral alien Reeves's muntjacs showed the cattle-type ITS genotype and cox1 cattle-I and II haplotypes. The rDNA and cox1 nucleotide sequences of G. nepalensis from a red fox in Sardinia were almost identical to those of the worms from domestic and wild ruminants on the island. The ecological interaction between domestic and wild mammals and their susceptibility to different Gongylonema spp. must be considered when trying to elucidate this spirurid's transmission dynamics in nature.

Excavation at Pauli Stincus in Sardinia has revealed an ancient plough soil, with associated evidence of intensive prehistoric agricultural activities.

Within the Variscan basement of Sardinia (Italy), two main Fe concentrations occur in the low-grade metamorphic tectonic units: (1) an uppermost-Ordovician oolitic ironstone of shallow anoxic water environment; and (2) a concentration of Fe oxyhydroxides lying on a palaeosurface. Two sets of samples were picked from the marine ironstone and from the continental Fe concentration following stratigraphic criteria. Chemical analysis, X-ray diffraction, scanning electron microscopy-energy dispersive X-ray analysis and thin-section studies were performed on 34 samples.

Marine ironstones formed under a highly reducing, anoxic, non-sulphidic methanic environment, and their Fe phases are chamosite, siderite and magnetite. Detrital chlorite and illite, produced during physical weathering, were chamosite precursors. Using the V/Cr proxy, an emergence stage that caused a transition to an oxic environment is documented. In contrast, continental ironstones formed under oxic conditions and the dominant Fe phase is goethite, which can adsorb Zn2+ and U6+. Unexpected negative Ce anomalies occur in this set of samples, suggesting that the oxyhydroxides originated from Ce-depleted solutions. Although the ironstones of Sardinia formed in different environments (marine vs. continental) and under contrasting climatic conditions (sub-glacial vs. tropical) they share similar geochemical features. These dramatic palaeoenvironmental differences did not result in large differences between the geochemistry of the chemical sediments.

Recent studies on albitite rocks located in the granodiorite complex of Central Sardinia have revealed that epidote has a widespread occurrence as a light rare-earth element (LREE)-bearing accessory common phase. Titanite has been recorded as a heavy rare earth element (HREE)-bearing mineral. The Hercynian granodiorite complex of Central Sardinia is composed chiefly of quartz, Ca-plagioclase, K-feldspar and biotite and of a wide variety of secondary assemblages, mainly allanite, titanite and zircon. Albitic plagioclase and quartz are the main mineral components of the albitites. Additional minerals include, besides allanite and epidote, a more calcic-plagioclase (oligoclase), K-feldspar, chlorite, titanite and more rarely muscovite. The mineral assemblages and REE-bearing minerals of albitites were analysed by wavelength dispersive spectrometry (WDS). Chemical data suggest that there is a near complete solid-solution between epidote and allanite whereas little variations in HREE of titanites were detected. In epidote-group minerals a pronounced zoning in REE was observed while titanite was recorded unzoned. Textural relations were studied by SEM to distinguish primary from secondary epidotes. Chemical criteria to recognize magmatic from alteration epidotes were also applied. The alteration epidotes mainly occur and generally originate from plagioclase alteration and from leaching of magmatic allanite. Comparison of textures using both the SEM technique and EPMA data showed that the characteristic ‘patchy zoning’, observed in epidotes, corresponds with different amounts of REE in these minerals.

The schematic model proposed for the epidote-forming reactions during the metasomatic processes that affected the granodiorites involves: (i) the instability of the anorthitic component of plagioclase; (ii) the simultaneous formation of albite; (iii) the leaching of the magmatic allanite with a redistribution of REE in the epidotes of the albitites.

Mineralogical-chemical techniques (XRD, SEM/EDX, WDXRF) and a sequential selective extraction procedure were applied to mine-waste materials and stream sediments from the Baccu Locci stream catchment (Sardinia, Italy) affected by serious As contamination as a consequence of past mining. Results indicate that solid-state speciation of As is mainly dominated by the presence of Fe(III) hydroxides (arsenical ferrihydrites with various Fe/As molar ratios) occurring as coatings of silicate grains, in which As is contained as sorbed or co-precipitated species. Scorodite (FeAsO4·2H2O) is common too, whereas arsenopyrite is generally subordinate but, owing to its relatively rapid oxidation, environmentally significant. Moreover, some unidentified arsenates of Ca-Fe or K-Fe were also detected. Arsenic contained in these phases is slowly, but continuously, released in relatively small amounts through three main mechanisms: (1) oxidation of residual arsenopyrite to scorodite; (2) decomposition of scorodite into a hydroxide or oxide of Fe(III); (3) desorption/release from Fe(III) hydroxides. Decomposition of the unidentified arsenates is also probable, e.g. Ca-Fe arsenate → calcite + Fe(III) hydroxide + As release. The flotation tailings are widely scattered and distributed in the middle–lower Baccu Locci stream catchment, and represent the most dangerous As-generating contamination source in the study area.

At the abandoned pyrite mine at Genna Luas (Sardinia, Italy), melanterite is the most environmentally important secondary phase associated with pyrite oxidation. A complete cycle, including formation on pyrite surface, dissolution in water, precipitation from water and subsequent alteration, can be observed. The oxidation of pyrite to melanterite is related mainly to the ‘intrinsic’ features of the Genna Luas pyrite, such as its cryptocrystalline pseudo-colloidal texture. During melanterite formation on pyrite there is transient storage of Fe2+, SO42- and acidity. This is controlled mainly by wetting-drying seasonal cycles. Laboratory experiments have shown that the simple dissolution of melanterite is an acidity-generating process which affects the geochemistry of water and, indirectly, contributes to the supply of the Fe3+ required for the aqueous oxidation of pyrite. According to this geochemical model, the interaction between rainwaters and ground pyritic materials accumulated in heaps generates hyperacidic saline waters (pH = 0.6; TDS = 300 g/l) with very high SO42+ contents (203 g/l), Fe2+ contents (73 g/l), Zn contents (11 g/l), and numerous potentially toxic elements. Melanterite precipitates from these waters (SIMelanterite = 0.15, calculated using PHRQPITZ software), giving rise to attractive emerald green crystal aggregates which, when exposed to air, alter to a fine white powder composed mainly of melanterite, and minor amounts of rozenite and szomolnokite.