The compositional variation in a multi-coloured, zoned tourmaline from the Cruzeiro pegmatite, Brazil, reflects melt chemical evolution during the entire pegmatite differentiation. In uncontaminated granitic pegmatite systems such as that of Cruzeiro, the compositional evolution of tourmaline progresses from schorl to fluor-elbaite, rather than directly from schorl to elbaite, to reflect co-enrichment in Li and F during fractional crystallization.

The CaSiO₃ system exhibits structural complexity with various polymorphs under different pressure and temperature conditions. This study stabilizes a new high-pressure polymorph, parabreyite, via multianvil syntheses at 4–5 GPa and 600–800 °C. Parabreyite's triclinic structure, with distinct threefold tetrahedral rings, was solved using 3D electron diffraction and X-ray diffraction. Elastic properties, thermal expansion and Raman spectra differences with breyite were analyzed.

Dacostaite is a new fluoride–arsenate mineral found in the Sb(Au) deposit of the Cetine di Cotorniano Mine (Tuscany, Italy). It shows a novel crystal structure formed by heteropolyhedral layers and isolated Mg(H₂O)₆ groups connected by H bonds. The heteropolyhedral layers are similar to those occurring in alunite-supergroup minerals, and this is a further example of the ability of nature to use similar modules in forming the large number of currently known structural arrangements. 

In this work, we used Fourier-transform infrared (FTIR) spectroscopy to analyse 25 rubies and sapphires, including natural, synthetic, and treated specimens. By optimising sample positioning, we identified distinct spectral fingerprints for each type and treatment. This systematic approach enhances gemstone identification accuracy and contributes valuable data to existing gemological databases, enabling faster and more reliable analyses in the future.

Andreybulakhite, ideally Ni(C₂O₄) · 2H₂O, is a new oxalate mineral, which was discovered on the Kola Peninsula, Russia. Andreybulakhite forms segregations of crystals up to 2 × 1 × 1 mm in size disseminated within the fruiting bodies of Lecanora cf. polytropa lichen, whose colonies overgrow the oxidized surfaces of pyrrhotite–pentlandite–chalcopyrite ore. Andreybulakhite is named in honour of Andrey Glebovich Bulakh of Saint Petersburg State University.

Heimaeyite (Na₃Al(SO₄)₃) has been found in fumaroles on Eldfell volcano, which lies on the island of Heimaey, Iceland. Its crystal structure contains Al–sulfate chains and belongs to a known structure type that also comprises K–Nb, K–Ta, Na–V, and Na–Fe representatives. We registered small Fe–Al substitution in heimaeyite, which might indicate a solid solution between Na–Al and Na–Fe compounds. We investigated the specimen with electron microscopy, an electron microprobe, and X-ray diffraction.

The amorphous phase of the natural mineral olivine was synthesized to investigate its mechanical properties. Tensile tests with in situ optical microscopy revealed brittle behaviour of amorphous olivine. Using digital image correlation, we estimated the intrinsic strength of amorphous olivine to be about 1.8 GPa. The measured intrinsic strength of amorphous olivine should help to better identify the “weak link” that initiates or promotes macroscopic material failure.

Many chemical elements occur in rocks, in ore deposits, and in the environment in trace amounts. One of them is the element tungsten. It is not clear, however, where the trace amounts of tungsten reside and how they move around. In this work, we found that the element tungsten can be carried by a common iron oxide mineral, hematite. It can be transported in hematite and released under appropriate conditions, for example in reducing environments.

Tungsten (W) concentrations in fluids in equilibrium with crystalline tungsten oxide are used to improve constraints of thermodynamic parameters for W solubility. W species in the hydrothermal fluids are further characterized by X-ray spectroscopy. Improved thermodynamic properties for a set of W fluid species are provided that cover a wide range of fluid compositions, necessary for understanding and describing the complex processes of W enrichment and mineralization in hydrothermal systems.