Dauphiné twin (DT) domains in a deformed quartz were visualized for the first time by using orientation-optimized electron channelling contrast imaging under Bragg conditions of the rhombohedral planes. The different contrast of a pair of DT domains in the backscattered electron images originates not from a misorientation between the two domains but from different diffraction intensities between positive and negative rhombohedral planes in quartz.

Lascar volcano, located in northern Chile, is among the most active volcanoes of the Andes. Its activity culminated in the last major explosive eruption in April 1993. We carried out experiments at high temperatures (up to 1050 °C) and pressures (up to 5000 bar) in the lab, and we used a wide variety of geochemical methods to provide comprehensive constraints on the depth and temperature of the magma chamber beneath Lascar volcano.

This work deals with a challenging case of a commercial clay from Gomsiqe–Puka (Albania) contaminated by mineral fibres. Detection and quantification of asbestos in this material push the boundaries of current experimental methods. Using TEM, micro-Raman spectroscopy, and EPMA, we identified the presence of asbestos tremolite, along with a rare fibrous variety of diopside. The impact of milling on the detection and quantification of mineral fibres was also evaluated.

In this study, we analyze a peculiar eclogite from the Western Alps, which not only recorded a classical subduction-to-exhumation path but revealed evidence of Ca-rich fluid–rock interaction. Chemical composition and modeling show that the rock experienced peak metamorphic conditions followed by Ca-rich pulsed fluid influx occurring consistently under high-pressure conditions. This research enhances our understanding of fluid–rock interactions in subduction settings.

The discovery of the K-dominant tourmaline maruyamaite with microdiamond inclusions suggested its ultrahigh-pressure formation. We analyzed the role of K in the tourmaline structure, with a special focus on its stability. High pressure is necessary to squeeze the large cation K⁺ in the stiff framework of tourmaline, although K is the underdog component if Na⁺ is present in the mineralizing fluid. K-tourmaline is stable at high pressure, overcoming the stereotype of a mere crustal component.