We provide new insights into the release of H₂O from the phonolitic melt of the Laacher See volcano. Decompression experiments conducted at superliquidus conditions revealed uniformly dispersed vesicles throughout the samples, with extremely high vesicle numbers regardless of the decompression rate. These findings enhance our understanding of volcanic eruptions and might suggest that rapid volatile release due to off-critical spinodal decomposition increases explosive volcanic activity.

As magma ascends, H₂O-supersaturated melt forms fluid vesicles, creating high vesicle number densities (VNDs) and increasing melt porosity, accelerating magma ascent. This study examines how VNDs vary with decompression rate as vesicles begin to coalesce. The shift from decompression-rate-independent to decompression-rate-dependent VND can strongly influence eruption styles, creating permeable channels or forming closed-porosity foams that trap pressurized gas, potentially leading to explosive eruptions.

An unusual tourmaline was studied using a multi-analytical approach. The sample comes from a granitic pegmatite on the island of Elba and consists of three generations of tourmaline: green prismatic tourmaline, a dark fibrous cap, and colourless acicular single crystals. The most likely scenario for its formation involves the miarolitic cavity fracturing due to mechanical shock, the subsequent circulation of the highly reactive cavity fluids, and the leaching of accessory biotite in the surrounding pegmatite.

Garnet crystals record the evolution of the pressure–temperature conditions during their growth. Thermodynamic modelling and the presence of coesite inclusions testifies that these rocks equilibrated along a pressure–temperature path crossing the equilibrium between quartz and coesite. This allows for discussing the role of energetic barriers during crystal growth. This was found insignificant, except for rocks that contain previous garnet crystals that have difficulties to achieve equilibrium.

In this work, we present the most iron-rich chrysoberyl discovered to date, found in the Sabatini Volcanic Complex (Latium, Italy). We provide a comprehensive overview of its chemical, structural, spectroscopic, and optical properties. The characterization of this chrysoberyl reveals several unique features, offering valuable insights into its genetic model and geochemical constraints, which are consistent with existing literature on the Sabatini complex and with ongoing research.

This study describes the elbaite neotype, found in crystals from a site on Elba island, Italy. Researchers analyzed these nearly colorless crystals and found that their formation was influenced by earlier changes in the surrounding rock. As different minerals formed first, they set the stage for elbaite to develop later in deeper spaces. This work helps us understand how changes in the local environment affect how and when certain minerals grow.

A thorough multimethod characterisation of the green dolomite sampled at the Malentrata magnesite mine has been carried out. We observed (1) a peculiar reduction of the cell volume and (2) the origin of the peculiar green colour, mainly determined by the Fe electronic transitions, probably in combination with those of Cr. In fact, the green dolomite of Malentrata contains aliquots of a number of environmentally relevant elements, in particular Mn, Cr, and Ni.

The thermal reaction Fe²⁺ + OH^- → Fe³⁺ + O^2- + e^- + H⁺ in hydrous silicates has tremendous implications in planetary-scale phenomena like electrical anomalies, water cycling, seismicity, volcanism, and ore generation. We annealed riebeckite crystals up to 750 °C and P = 0.7 GPa and show that the amphibole stability is extended without any Fe oxidation, implying that thermally activated electron hopping contributes to the electrical conductivity of lithospheric rocks during subduction.

Natrolitised Early Cretaceous metaplutonites (melteigites, ijolites) contain various accessory minerals. The natrolitisation was a very low-temperature process, which did not affect most of the primary minerals, including most of the accessories. The evidence shows the release of barium and strontium, possibly from feldspathoids, from primary Na–Ca feldspars, and optionally also from glass, during the natrolitisation.