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Paramontroseite is a V dioxide (a = 4.8960(14) Å, b = 9.395(3) Å, c = 2.9163(5) Å, V = 134.14(6) ų; space group Pbnm). The sample under investigation (Prachovice mine, Czech Republic) bears 20 wt % of Fe₂O₃, and the Fe atoms occupy tetrahedral sites arranged in the empty channel along z. Thermal expansion is anisotropic. At T > 350 °C, paramontroseite decomposes and two new phases form: V₂O₅ (V-pentoxide) and V₄Fe₂O₁₃ (Fe-tetrapolyvanadate).

In this work we have applied the elastic geobarometry approach to a Chinese diamond in order to determine the depth of formation of an olivine-bearing diamond. Together with the temperature of residence at which the diamond resided in the mantle, we were able to discover that the diamond was formed at about 190 km depth. Beyond the geological meaning of our results, this work could be a reference paper for future works on Chinese diamonds using elastic geobarometry.

The first occurrence of centimeter-thick PS-15 polygonal serpentine veins from ultramafics of Monte Avic, Val d'Aosta, is here reported. The combined mineralogical study led by three techniques with different resolutions has provided new analytical tools capable of recognizing the PS-15 polygonal serpentine. In particular, X-ray powder diffraction data (XRPD) and micro-Raman recognize polygonal serpentine more quickly and easily than transmission electron microscopy (TEM) but equally rigorously.

Pyrite crystals with rhombohedral morphology have been known for a long time and were considered up to now as curiosities. The morphological study of well-crystallized, centimeter-sized crystals, often twinned, from the Madan Pb–Zn ore field permitted us to define such a pyrite variety as a pseudo-cubic trigonal derivative of pyrite.

This work presents an in-depth description of a new design for a high-temperature gas-mixing furnace using a mixture of CO–CO₂–SO₂. It has been designed and built with user safety in mind. The furnace can sustain temperatures of up to 1650 °C. This furnace sets itself apart with its size and unique quench mechanism. Crucially, the apparatus has the ability to change the gas mixture during an experiment. This feature allows the user to simulate natural environments, such as volcanoes.

The coexistence of chloritoid and biotite in medium-pressure Barrovian terranes is uncommon, with chloritoid usually occurring at lower temperatures than biotite. A petrologic approach using equilibrium thermodynamic modelling points out how metapelites can attain H₂O-undersaturated conditions even at medium pressure and amphibolite-facies conditions and consequently can be affected by kinetic barriers, which need to be taken into account.

Manganrockbridgeite, Mn²⁺₂Fe³⁺₃(PO₄)₃(OH)₄(H₂O), a new member of the rockbridgeite group, has been characterised using electron microprobe analyses, Mössbauer spectroscopy, optical properties and single-crystal X-ray diffraction. Whereas other rockbridgeite-group minerals have orthorhombic symmetry with a statistical distribution of 50%Fe³⁺/50% vacancies in M3-site octahedra, monoclinic manganrockbridgeite has full ordering of Fe³⁺ and vacancies in alternate M3 sites along the 5.2 Å axis.

We provide a tool for fast preparation-free estimation of the Fe³⁺ content in Al–Fe³⁺ series epidotes by Raman spectroscopy. The peaks near 570, 600, and 1090 cm⁻¹, originating from Si₂O₇ vibrations, strongly correlated with Fe content, and all three signals are well resolved in a random orientation. Among them, the 570 cm⁻¹ peak is the sharpest and easily recognized. Hence, the linear trend, ω₅₇₀ = 577.1(3) − 12.7(4)x, gives highly reliable Fe content, x, with accuracy ± 0.04 Fe³⁺ apfu.

Although rutile does not have water in its chemical formula, it can contain trace amounts. We applied a new measurement protocol to study water incorporation into rutile from eight geological environments. H₂O in natural rutile can be linked to six crystal defects, most importantly to Ti³⁺ and Fe³⁺. Quantifying the H₂O in the individual defects can help us understand relationships of trace elements in rutile and might give us valuable information on the conditions under which the rock formed.

We report a comprehensive data set characterizing and quantifying two types of mineral defects in the most abundant mineral of Earth's upper mantle: olivine. Namely, we investigate translation defects of dislocation and rotation defects, called disclinations, in polycrystalline olivine deformed in uniaxial compression or torsion, at high temperature and pressure. The defects are identified via mapping of the crystallographic disorientation detected using electron backscatter diffraction.

Synthetic lepidolites and Li-muscovites were characterised by nuclear magnetic resonance (NMR) spectroscopy and X-ray diffraction. Both Li and F / OH content influence the occurrence of the impurity phases. A solid solution series exists for lepidolites with polylithionite and trilithionite as endmembers but does not between trilithionite and muscovite. NMR investigations indicate there is a preference for incorporating fluorine and OH groups near Li-rich and Al-rich environments, respectively.

Pleysteinite has been approved as a new mineral species, and we describe here the characterisation of the mineral and its relationship to related minerals benyacarite, paulkerrite and mantienneite. The characterisation includes the determination and refinement of the crystal structure, electron microprobe analyses, optical properties and interpretation of its Raman spectrum.

The carbonation of peridotites occurs during the fluxing of reactive CO²-bearing fluids, ultimately producing listvenites (magnesite and quartz assemblage). We studied the most extended outcrops of listvenites worldwide, found at the base of the Semail Ophiolite (Oman). Our study highlights the partitioning of iron during early pervasive carbonation revealed by chemical zoning in matrix magnesites, and we discuss the conditions favoring the formation of Fe-rich magnesite.

This research was done to understand how toxic elements, such as copper or arsenic, move through the environment. The data presented here can be used to model mobility of such elements and to improve remediation strategies at sites contaminated by mining.

Alicewilsonite-(YCe), a new mckelveyite group, was found at Mont Saint-Hilaire, Quebec, Canada, and subsequently at the Saint-Amable sill, Quebec, Canada, and the Khibiny Massif, Kola Peninsula, Russia.

A new mineral group – the mckelveyite group – consisting of seven carbonate minerals was established. One of the seven members, donnayite-(Y), was re-investigated and its belonging to the mckelveyite group was confirmed.

Volatile diffusivities in silicate melts control the nucleation and growth of bubbles in ascending magma. We investigated the diffusion of CO₂ in an anhydrous and hydrous leucititic melt at high temperatures and high pressure. CO₂ diffusion profiles were measured via attenuated total reflection Fourier transform infrared spectroscopy. CO₂ diffusion increases with increasing temperature and water content. The data can be used to understand the CO₂ degassing behaviour of leucititic melts.