Metamorphic rocks affected by a fault have undergone chemical, mineralogical, and textural changes. The most significant is the enrichment in clay minerals (chlorite, kaolinite, and smectite). Geothermometry of the new chlorites made it possible to determine the temperatures of the processes (predominantly < 225°C), promoted by the fault dynamics (mainly fluid-related alterations). The retrograde alteration also affected the fluid-accessible zones of the original rocks, with growth of the same clay minerals.

Mineralogical, paragenetic, and geochemical data on sulfidic mineralization from the Cínovec greisen-type deposit show that distribution of sulfides is irregular and not strictly bound to prevalent Li–Sn–W mineralization. Progressive development of metal contents in the reduced sulfide-bearing hydrothermal fluid proceeds from Zn–Cu–Sn to Pb–Bi–Ag and As–Sb. Late-stage sulfate- and fluorine-bearing fluids partly altered earlier mineralization but did not deposit significant ore content.

Black opal, a rare amorphous SiO₂ variety, results from the interaction of silica with organic matter and therefore hints at traces of life, including the early Earth and Mars. The Volyn occurrence is one of the few examples of black opal worldwide and is the unique case of a pegmatitic occurrence in a granite; its age is at least 200 Ma. The structure consists of micrometer-large sphere-like arrangements of nano-sized grains and shows shape relicts of fossils, known from Volyn as "kerite".

Argentotennantite-(Fe), ideally Ag₆(Cu₄Fe₂)As₄S₁₃, is a new member of the tetrahedrite group found in the San Genaro mine, Castrovirreyna Province, Huancavelica, Peru. It occurs as anhedral grains up to 100 μm in size, or, more commonly, it forms micrometer-sized rims around crystals of argentotetrahedrite-(Zn) or replaces the latter around cavities and fissures, along with Ag-rich tennantite-(Fe). It is cubic, I3m, with a = 10.4365(5) Å, V = 1136.75(17) ų.

The paper is on the new mineral species piilonenite-(Nd), a new Nd-dominate carbonate with no closely related minerals or synthetic compounds from Mont Saint-Hillarie, Canada.

Deposits of bat guano in cave environments host diverse assemblages of secondary minerals, which can go through partial dehydration processes in response to varying environmental conditions. In this article, we investigate the thermodynamics and kinetics which lead guano-derived taranakite to lose part of its structural water and transform into francoanellite. Our results allow us to present evidence-based hypotheses to explain the occurrence of the latter in natural environments.