Zinkgruvanite, a barium manganese iron silicate with sulfate, is a new mineral found in drill core samples from the Zinkgruvan zinc, lead and silver mine in Sweden. It is associated with other minerals like baryte, barytocalcite, diopside and sulfide minerals. It occurs as flattened and elongated crystals up to 1 mm. It is almost black. Zinkgruvanite is closely related to the mineral yoshimuraite and based on its crystal structure, grouped with the ericssonite group of minerals.

Dense hydrous magnesium silicates, like the 3.65 Å phase, are thought to cause deep earthquakes. We investigated the dehydration of the 3.65 Å phase at P and T. In both directions of the investigated simple reaction, additional metastable water-rich phases occur. The observed extreme reduction in grain size in the dehydration experiments might cause mechanical instabilities in the Earth’s mantle and, finally, induce earthquakes.

Dark patinas rich in manganese (Mn) developed on several sandstones of the Lunéville château (France) contrasting with the general yellow color of the building. The characterization of the Mn compounds in the patinas, but also in the building stones, allowed us to propose a model for the patina formation based on the dissolution of the Mn phases initially present in the stone bulks. The results obtained in this study might enlighten processes occurring on other buildings or in natural settings.

In the paper we discuss the origin of large chamber pegmatite bodies which contain giant gem-quality crystals of black quartz (morion), beryl, and topaz. We conclude that these pegmatites develop under the influence of later intrusions of mafic rocks that cause reheating of the partly crystallized granite massifs and that they supply a large amount of fluids that facilitate the inflation of pegmatite chambers and crystallization of giant crystals of various minerals.

This work reports the full crystal-chemical characterization of gersdorffite from Contrada Zillì (Peloritani Mountains, Sicily, Italy). The structural type shown by gersdorffite (ordered polytype 2₁3) and its chemistry agree with low-temperature crystallization conditions. Moreover, the chemical zoning of the studied crystals recorded changes in the crystallization physicochemical conditions. This zoning may be due to a multistage crystallization, related to the evolution of the ore deposits.

Ellinaite, a natural analog of β-CaCr₂O₄, was discovered at Hatrurim Basin, Israel, and in an inclusion within the super-deep diamond from the Sorriso Creek placer, Brazil. Chemical composition, structural data and physical properties are given for this mineral. It is related to multiple oxides AB₂O₄ with tunnel structure. This group now includes eight minerals. The overview of ellinaite from all localities suggests different PT–X–fO₂ conditions for the mineral and its host rocks.

The study presents and discusses mid- and near-infrared spectra of three Mg–Ni mineral series (serpentine-like and talc-like minerals, sepiolite) commonly found in reactivated faults and sequences of clay infillings of the New Caledonian Ni-silicate deposits. This spectroscopic study sheds light on the nature of the residual mineral phases found in the clay infillings (serpentine-like minerals) and reveals the aptitude of the newly formed minerals (talc-like minerals and sepiolite) to store Ni.