Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding problem in our understanding of porphyry ore deposit formation. We approach this problem by investigating the oxidation state of magmatic sulfur, which controls the behavior of ore-forming metals during magma differentiation and magmatic-hydrothermal transition. We use sulfur in apatite to reconstruct the sulfur oxidation state in the Gangdese batholith, southern Tibet. We find that magma sulfate content increased abruptly after India-Eurasia collision. Apatite sulfur content and the calculated magma S⁶⁺/ΣS ratio correlate with whole-rock dysprosium/ytterbium ratio, suggesting that residual garnet, favored in thickened crust, exerts a first-order control on sulfur oxidation in magmatic orogens. Our findings link sulfur oxidation to internal petrogenic processes and imply an intrinsic relationship of magma oxidation with synmagmatic crustal thickening.

Trace amounts of water dissolved in minerals affect density, viscosity and melting behaviour of the Earth’s mantle and play an important role in global tectonics, magmatism and volatile cycle. Water concentrations and the ratios of hydrogen isotopes in the mantle give insight into these processes, as well as into the origin of terrestrial water. Here we show the presence of molecular H₂ in minerals (omphacites) from eclogites from the Kaapvaal and Siberian cratons. These omphacites contain both high amounts of H₂ (70 to 460 wt. ppm) and OH. Furthermore, their ∂D values increase with dehydration, suggesting a positive H isotope fractionation factor between minerals and H₂–bearing fluid, contrary to what is expected in case of isotopic exchange between minerals and H₂O-fluids. The possibility of incorporation of large quantities of H as H₂ in nominally anhydrous minerals implies that the storage capacity of H in the mantle may have been underestimated, and sheds new light on H isotope variations in mantle magmas and minerals.

The friction of magnetene is found to be low despite its covalent bonding, which is correlated to its 2D confinement effects.

The Mineral Identification by Stoichiometry (MIST) algorithm can identify mineral species in geochemical data sets. MIST is applied to X‐ray fluorescence chemical analyses from the Planetary Instrument for X‐ray Lithochemistry (PIXL) on the Mars 2020 Perseverance rover to identify mineral phases in abraded rock targets at Jezero crater. We used a Monte Carlo (MC) error propagation technique to assess confidence in the results. Our study reports 24 high‐confidence mineral phases from the first 1100 sols of Perseverance's traverse. Primary mineral groups include plagioclase, pyroxene, and olivine, in agreement with previously published results, and support an (ultra)mafic rock source. Additionally, MIST identified a range of phyllosilicate minerals, including nontronite, saponite, hisingerite, greenalite, minnesotaite, and sepiolite; identification of such alteration phases is essential for constraining the aqueous alteration history of Jezero's rocks. An initial survey of the reported phases suggests multiple, distinct stages of fluid alteration in Jezero's history: high temperature and acidic, moderate temperature and circumneutral, and later stage ambient alkaline conditions. MIST results from PIXL data help determine rocks of interest on Mars' surface for investigation by Perseverance and will also be important for informing analysis of samples when returned to Earth.

A petrographic investigation of ore samples from the Assarel porphyry copper deposit in the Srednogorie metallogenic zone (Bulgaria) constrains the setting and character of precious metals (Au, Ag, PGE) and related minerals within the deposit. This work supports renewed interest in understanding the deportment of precious metals and provides mineralogical knowledge during the testing and validation of novel drill core 3D X-ray computed tomography–X-ray fluorescence (XCT-XRF) scanning technology being developed as part of the X-MINE project. Scanning electron microscopy–energy dispersive spectrometry (SEM-EDS) results indicate precious metals occur in their native state (Au, Ag), as sulfides (Ag), sulfosalts (Au), tellurides (Ag, Pd), and selenides (Ag), and typically form micron-sized inclusions in pyrite and chalcopyrite or are disseminated in the groundmass of the rock. Preservation of early Fe oxide–chalcopyrite ± bornite assemblage as relics in the more dominant pyrite-chalcopyrite mineralization assemblage supports mineral disequilibrium relationships and multi-stage mineralization events. Several rare minerals (e.g., merenskyite, acanthite, sorosite, tetra-auricupride, auricupride, greenokite, bismuthinite, nagyagite, native Ni) are reported for the first time at Assarel and highlight the mineralogical diversity of the ore. The occurrence of precious metals and related minerals at Assarel attest to a complex hydrothermal system that underwent progressive physicochemical changes during the evolution of the mineralizing system (e.g., redox conditions, fluid chemistry).