We conducted this research to gain understanding of the mineral rouxelite, which contains elements like antimony, copper, mercury, and lead. Using advanced X-ray techniques, we re-examined its crystal structure and discovered new details, such as unit-cell parameters, symmetry, and substitutions. These findings provide accurate information about how the mineral forms and behaves. This work not only updates scientific knowledge of rouxelite but also offers insights into its chemical complexity.

Chromites found within the fusion crust of ordinary-chondrite meteorites display significant differences with respect to chromites found in the interior of the same meteorites. Chromites within the fusion crust, when compared to those in the interior of the meteorite, display a significantly higher Mg / (Mg + Fe) ratio; moreover, ca. 15 % of the chromites formed within the crust display small but detectable amounts of Ni.

A new rare-earth-bearing silicate is described from a manganese ore deposit in the Pyrenees. It belongs to the epidote family and is characterised by the formula Mn²⁺Ce(MgAlMn²⁺)(Si₂O₇)(SiO₄)F(OH).  This new mineral commonly contains inclusions of an Mn-rich yttrium borosilicate, a potentially new mineral of the hellandite family. This is a new type of occurrence for hellandite – while rare earths are under the spotlight.

The Léon region in France offers a window into the dramatic geological processes that shaped continents. Studying ancient rocks called eclogite, we uncovered a history of magma generation, deep burial and rapid crustal movement between 390 million and 300 million years ago. The area was shaped by subduction dynamics, where shifting tectonic plates stretched and compressed the crust. These findings help us understand how ancient geological processes continue to influence the Earth’s surface today.

Zircon in highly differentiated systems such as rare-metal granites often exhibits unusual texture and composition that need to be clarified. Based on a detailed study on zircon from the Beauvoir rare-metal granite (France), we show that zircon crystals were partially replaced during the magmatic–hydrothermal transition of these systems, resulting in a significant change in their crystal texture and chemistry.

Single-crystal X-ray diffraction has been used to characterise the structural properties of a CaIrO₃ orthorhombic perovskite-type structure under ambient and high pressures. It has been found that the structure of this compound is more distorted than other CaO perovskites. Structural determination at high pressure also shows a peculiar compression behaviour that is different from the other CaO perovskites. This explains why this material is much stiffer than expected.

Seventeen tourmalines from Brazil were investigated by structural and chemical techniques. Most samples are Na-dominant and belong to the alkali group. They correspond to fluor-elbaites or elbaites, except one sample, which corresponds to a rossmanite. Structural data indicate that the B site is fully occupied by boron, that the T site is occupied by Si, and that the Z site is mainly occupied by Al. The X site contains vacancies, Na, K, and Ca, and the Y site is mainly occupied by Li, Al, and Fe²⁺.

Marioantofilliite, ideally [Cu₄Al₂(OH)₁₂](CO₃)•3H₂O, is a new member of the hydrotalcite supergroup occurring as a supergene mineral in the Cu–Fe deposit of Monte Copello–Reppia (Liguria, Italy). Its name honours Mario Antofilli (1920–1983) for his contribution to the knowledge of the mineralogy of Liguria. Its discovery and description improve the knowledge of layered double hydroxides (LD), with implications for the group of Cu–Al LDH actively studied for its technological properties. 

A suite of clinopyroxenes from ankaramitic magmas of the Miocene Teno massif and Roque del Conde shield volcanoes (Tenerife, Canary Islands) were studied to obtain geothermobarometric information on the anatomy of the volcano plumbing system.

Suenoite is a new Pnma amphibole discovered in the Mn ore deposit of Scortico–Ravazzone, Apuan Alps, Tuscany, Italy. Its discovery adds further complexity to the amphibole supergroup, and it represents the first Pnma amphibole with ^BMn²⁺.

Calcium silicate perovskite (Ca-pv) is the third most abundant mineral in Earth's interior. Knowledge of its elasticity is significant for deciphering the origins of seismic signatures. Elasticities and sound velocities of Ca-pv have been theoretically investigated. Compositional effects on elastic properties and velocity anisotropies of Ca-pv are significant at lower-mantle pressures. Ca-pv may be related to the observed seismic anomalies associated with subducted oceanic crust in the lower mantle.

During project STARDUST, over 5500 specimens were recovered. Among them, a micrometeorite from Oslo (NMM/L2) revealed a new Al–Cu alloy with Al₄Cu₉ stoichiometry. This phase was approved as a new mineral named jonlarsenite. The microspherule shows features typical of micrometeorites. Its extraterrestrial origin is confirmed by oxygen isotope composition and chondritic chemistry, similar to previously known Al–Cu meteoritic materials.

The two most recent eruptive events of Nisyros volcano (Greece) record the interaction between variably evolved magmas by the presence of mafic enclaves, indicative of multiple recharge events within the magma chamber. We use the mineral chemistry composition to constrain the location of the main eruptible reservoirs and their evolution at the transition from explosive to effusive activities, with implications for magma migration and storage in the crust.