We present the description of new mineral – a Cd-dominant member of the tetrahedrite group, tetrahedrite-(Cd), from the Radětice deposit near Příbram, Czech Republic. All necessary data including crystal structure were successfully determined, and the mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (number 2022-115).

The paper describes the formal establishment of the paulkerrite group of minerals and its nomenclature. It includes the application of a site-merging procedure, coupled with a site-total-charge analysis, to obtain unambiguous end-member formulae. Application of the procedure has resulted in the revision of the end-member formulae for several of the group members.

Despite many articles published about eruptions at Mt. Somma–Vesuvius (SV), the volatile contents of magmas associated with mafic (quasi-primitive) melts were not directly analyzed for many eruptions based on melt inclusions (MIs). We suggest that several high-Fo olivines formed at depths greater than those of the carbonate platform based on MI chemical composition. We also estimated that 347 to 686 t d^-1 of magmatic CO₂ exsolved from SV magmas during the last 3 centuries of volcanic activity.

We study Icelandic silica sinter samples formed in hot-spring environments to evaluate the effect of both temperature and microstructure on the spectral properties of hydrothermal opal. We show that spectral changes can be related to different parameters such as fluid temperatures, hydrodynamics, microbial activity, and silica micro-textures, which are specific to their environment of formation within hot-spring geothermal contexts.

The present study of mafic rocks from Jutulsessen, Gjelsvikfjella, extends the presence of high-pressure rocks in the Maud Belt in Dronning Maud Land, Antarctica. The physical conditions necessary for the development of these rocks were attained during continent–continent collision along the East African–Antarctic Orogen. The new data in this study largely confirm the geodynamic implication outlined by others for the region.

The present study is based on sample chemical and mineralogical analyses of oceanic sediment and rock that were collected in the Guaymas Basin during IODP Expedition 385. The contact aureoles are not only affected by maturation of organic matter and dehydration reaction, but mineralogical reactions concern all sediment components (silicates, sulfides, carbonates, organic matter) and can be the result of the combination of different stages of alteration during and after the sill emplacement.

Li is a critical element that is often enriched in pegmatites. To better understand the enrichment of Li in such systems, it is necessary to understand the underlying transport mechanisms. We performed experiments to investigate diffusion rates and exchange mechanisms of Li between a Li-rich and a Li-poor melt at high temperature and pressure. Our results indicate that fluxing elements do not increase the diffusivity of Li compared to a flux-free melt.

This article introduces a new nomenclature system for the cerite group minerals. This system was necessary to allow the nomenclature of new species of minerals that are currently being described.

Garnet often entraps small droplets of deep melts generated during mountain building processes. Using high-resolution techniques, we studied these droplets in order to provide hard numbers for the quantification of volatile budgets during crustal evolution, show how even melts formed at >1000°C contain water, and clarify how water behaves during metamorphism and melting at the microscale. Moreover, we provide the very first data on chlorine in natural melts from crustal reworking.

The chemical compositions of the synthetic minerals periclase and zincite in the MgO–ZnO binary system change smoothly and systematically with pressure when they exist together in equilibrium. We have studied these changes experimentally over a wide range of conditions and fitted the results to a thermodynamic model. The model may be used to predict the compositions of the coexisting phases accurately at high pressures and temperatures corresponding to the Earth’s crust and uppermost mantle.

Zircon preserves geologic rock history. Electron backscatter diffraction (EBSD) analysis is useful to visualize deformed domains in zircons. Zircons from the Himalayan high-pressure eclogites were analzyed for EBSD to identify intra-grain plastic deformation. The U–Pb isotope age dating, using Nano-SIMS, showed that plastic deformation likely affects the geochronological records. For geologically meaningful results, it is necessary to identify undisturbed domains in zircon via EBSD.

Using an innovative multi-analytical approach, we investigated the trace elements composition of spinel-group minerals in different ultramafic rocks from the Voltri Massif (Central Liguria, NW Italy). The knowledge of the trace elements within these minerals has an interesting implication both in petrological, mineralogical, and geochemical studies as well as environmental fields, since these elements can be potentially toxic and released into the environment during weathering processes.

We performed experiments to investigate the effect of water and chlorine on the growth of minerals called plagioclase, motivated by the evidence for the presence of water and chlorine with the formation of rocks with large plagioclase minerals. Our study shows that indeed water has an effect on the size and abundance of that mineral. The effect of chlorine on the growth characteristic is negligible. Our results have implications for the understanding of the formation of different rock textures.

Rock lenses from the diamond stability field (>120 km depth) within ordinary gneiss are enigmatic. Even more when these lenses form an alternating exposure pattern with ordinary lenses. We studied 10 lenses from W Norway and found that many of them have a hidden history. Tiny needles of quartz enclosed in old pyroxene cores are evidence for a rock origin at great depth. These needles survived the rocks' passage to the surface that variably obscured the mineral chemistry – the rocks' memory.

We examined the reaction phase A plus high-P clinoenstatite to forsterite plus water (Reaction 1) by means of in situ X-ray diffraction measurements with the large volume press at the synchrotron PETRA III, Hamburg. Contrary to other studies, in which all experiments on Reaction (1) were performed at a water activity of 1, the reversed experiments presented in this study were performed at reduced water activity with mole fractions of about X_H2O = X_CO2 = 0.5.