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.

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.

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.

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. 

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.

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.

We examined the influence of Al₂O₃ and H₂O on the position of the coesite–stishovite transition by means of in situ X‑ray diffraction measurements with the large-volume press at the synchrotron PETRA III in Hamburg. The position of the transition was found to be shifted almost in parallel by about 1.5 GPa to lower pressures compared to results for the pure SiO₂ system by Ono et al. (2017). Stishovite of this study containing Al and H is only partially quenchable but transforms back to coesite.

Nannoniite, Al₂(OH)₅F, is a new mineral species discovered in the Cetine di Cotorniano mine (Tuscany, Italy). Its description was possible through a multi-technique approach, and its crystal structure was solved through three-dimensional electron diffraction, revealing close relations with gibbsite. The partial replacement of (OH) by F induces subtle by detectable structural changes. This study reveals that Al hydroxides could be a source of F in geological environments.

The growing interest in lithium (Li) diffusion for the determination of timescales of magmatic events increases the necessity to better understand Li diffusion in common mineral phases. In this context we analyzed Li diffusion in plagioclase, one of the most common mineral phases. Our study is the first to confirm two diffusion mechanisms for Li in plagioclase, and our results indicate timescales derived from Li diffusion data in previous studies were underestimated by a factor of up to 100.

In situ U–Th–Pb dating of allanite and monazite provides a robust record of polymetamorphism in greenschist facies metapelites in the Austroalpine Unit. Variations in bulk rock Ca, Al and Na contents produced a wide range of REE-mineral-phase relationships and microstructures, making them excellent geochronometers in complex tectonic settings. Our new pressure, temperature, time and deformation data reveal Permian metamorphism and a major crustal-scale Cretaceous detachment.