Recent  

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.

Assignment of OH-stretching bands to specific atomic-scale environments in tourmaline is still debated, which motivates detailed theoretical studies of their vibrational properties. We have theoretically investigated the OH-stretching spectrum of foitite, showing that specific OH bands observed in the vibrational spectra of iron-rich and Na-deficient tourmalines are affected by the magnetic configuration of iron ions and X-site vacancy ordering.

The paper gives a characterisation of the new mineral species, whiteite-(CaMnFe), which has recently been approved as a new mineral (proposal IMA2022-077). The study included a single-crystal structure refinement that, when combined with electron microprobe analyses, confirmed that the mineral was a new member of the whiteite subgroup of the jahnsite group of minerals. Relationships between the crystal structure and the unit-cell parameters for the whiteite-subgroup minerals are discussed.

Dutrowite is the first tourmaline supergroup minerals having Ti as a species-defining chemical constituent. Its finding improves our knowledge on the crystal chemistry of this important mineral group and allows us to achieve a better picture of the mechanisms favouring the incorporation of Ti.

Bobtraillite is an extremely rare cyclosilicate with a unique composition and complex structure. In this paper, we describe the second occurrence of the extremely rare complex zirconium silicate. The results suggest that the ideal formula of bobtraillite could be written as (Na, □)₁₂(□, Na)₁₂Sr₁₂Zr₁₄(Si₃O₉)₁₀[Si₂BO₇(OH)₂]₆·12H₂O.

When detecting the light element boron in solid materials with, in part, considerably lower concentrations of boron than present in natural tourmalines by using the electron microprobe, irregularities become visible in the analyses. This was for the first time experienced in synthetic diamond that was contaminated with boron to achieve a blue color. With this work, one can check if boron analyses are reasonable, and if not, one can correct them.

Using neural networks with experimental data, we infer the relationship between pressure, temperature and shear properties of MgO. Fixing the form of the relationship, which is a common practice, provides the properties that are largely constrained by the form and not the data. Our approach provides realistic uncertainties in shear properties, which should improve uncertainty quantification in interpretations of observed shear wave speed to infer the structure and dynamics of the Earth’s mantle.

Members of the epidote supergroup, epidote, clinozoisite, allanite, and ferriallanite, are described from the calcium–aluminum silicate and thermometamorphic zones in drill cores obtained from the Mofete and San Vito wells in the Campi Flegrei (Italy) geothermal field. Compositional zoning is ubiquitous. The epidote group encompasses nearly the complete range of coupled Al–Fe³⁺ substitution, and the allanite group is light rare earth element enriched.

Distribution of major and trace elements during anatexis at the source area was investigated in a portion of Variscan mid–lower crust exposed at Palmi (Calabria, Italy). Reactive migration of migmatitic melt imparted a mineralogical and chemical signature in mafic rocks associated with migmatites and promoted the crystallization of amphibole by a coupled dissolution–precipitation process. Amphibole and accessory allanite control the distribution of incompatible elements from the anatectic zone.

Serpentines, magnesian clay-like minerals formed in subduction zones, contain iron in either ferrous or ferric form. The oxidation state of the iron form controls the composition of fluids that form when they are destabilized by heating. Results obtained here with Mössbauer spectroscopy are compared with X-ray spectroscopy and shown to be more reliable for serpentines and magnesium-rich chlorites. Fluids released by serpentines in subduction may be less oxidized than previously thought.

The near-infrared spectra of hydrous minerals involve OH stretching vibrations, but their interpretation is not straightforward due to anharmonicity and vibrational coupling. We analyze the spectra of well-ordered samples of talc, brucite and lizardite to better assess the various factors contributing to the absorption bands. The results clarify the relations between the overtone spectra and their fundamental counterparts and provide a sound interpretation of the two-phonon combination bands.

We present a detailed petrographic, microanalytical and bulk-chemical investigation of 36 mafic rocks from drill hole GT3A from the dike–gabbro transition zone. These varitextured gabbros are regarded as the frozen fillings of axial melt lenses. The oxide gabbros could be regarded as frozen melts, whereas the majority of the rocks, comprising olivine-bearing gabbros and gabbros, show a distinct cumulate character. Also, we present a formation scenario for the varitextured gabbros.