Recent  

In this work we report a new locality for the rare mineral hydroromarchite, Sn₃O₂(OH)₂. It was found not in a submarine environment but in soil at the Saint James Church archaeological site in Creussen, Germany. A tin artefact (a tin button) was exposed to weathering in soil for about 300 years. We solved and refined its structure based on single-crystal X-ray diffraction analysis.

We determined the physical conditions at the time of its entrapment for an inclusion pair hosted in a Siberian diamond (Udachnaya kimberlite) and found that it equilibrated under relatively oxidized conditions, near the enstatite–magnesite–olivine–diamond (EMOD) buffer, similarly to Udachnaya xenoliths originating from comparable depths. These results can be reconciled with models suggesting relatively oxidized, water-rich CHO fluids as the most likely parents for lithospheric diamonds.

It was determined that growth bands showing the straight birefringence in octahedral sectors and the enrichment of graphite inclusions in cuboid sectors of Zimbabwean mixed-habit diamonds may both be due to the fluctuation of temperature during crystallization, and they displayed positive anomalies of plastic deformation, residual stress, nitrogen concentration, and VN₃H defects. This conclusion clearly revealed the correlation between birefringence and spectroscopic properties of diamonds.

Minerals have complex crystal structures, but many common minerals are built from the same chemical building blocks. TotBlocks is a novel, open-source tool for investigating these structures. It consists of 3D-printed modules representing the silica tetrahedra and metal–oxygen octahedra that form the shared chemical building blocks of rock-forming minerals. TotBlocks is a low-cost visualization tool that relates mineral properties (habit, cleavage, and symmetry) to crystal structures.

We investigated the effect that fluoride and protons have on each other as structural neighbors in the mineral topaz. This was done using spectroscopic methods, which measure the interaction of electromagnetic radiation with matter. The forces between atoms distort the spectroscopic signals, and this distortion can thus be used to understand the corresponding forces and their effect on the physical properties of the mineral.

Stannite decomposition leads to the precipitation of an amorphous and metastable Sn–Fe–As-rich phase. With ageing, goethite and cassiterite crystallize from the precursor and mark the end of the weathering cycle. Other elements are lost in the initial stage of weathering (e.g. Zn, S) or after full oxidation of the sulfidic material (e.g. Cu, Ag). Electron microprobe (EMP) and transmission electron microscopy (TEM) analyses were performed to witness the mobility of the released elements.

Volcanoes on Earth are divided into monogenetic and composite volcanoes based on edifice shape. Currently the evolution from monogenetic to composite volcanoes is poorly understood. There are two distinct magma chambers, with a deeper region at the Moho and a shallow mid-crustal zone in the Wulanhada Volcanic Field. The crustal magma chamber represents a snapshot of transition from monogenetic to composite volcanoes, which experience more complex magma processes than magma stored in the Moho.

A new mineral has been discovered, an amphibole, with the name ferri-taramite, which has now been approved by the International Mineralogical Association. The paper discusses the significance of the discovery in relation to other amphiboles found worldwide. This taramite is unique in that it is from a skarn associated with ore and is not of magmatic origin. For the description we have used many methods, including X-ray diffraction, chemical analyses and several types of spectroscopy.

First occurrences of the secondary phosphate minerals kenngottite, Mn₃²⁺Fe₄³⁺(PO₄)₄(OH)₆(H₂O)₂; allanpringite, Fe₃³⁺(PO₄)₂(OH)₃·5H₂O; iangreyite, Ca₂Al₇(PO₄)₂(PO₃OH)₂(OH,F)15·8H₂O; and nizamoffite, MnZn₂(PO₄)₂(H₂O)₄, from the Hagendorf Süd pegmatite are reported, with characterisation of their crystal chemistry and phase associations.

Ferro-ferri-holmquistite (IMA2022-020), ideal formula ☐Li₂(Fe₃²⁺Fe₂³⁺)Si₈O₂₂(OH)₂, was found in albitized granite from the Iwagi islet, Ehime, Japan. It is a Fe²⁺Fe³⁺ analogue of holmquistite and belongs to the lithium subgroup amphiboles. Ferro-ferri-holmquistite occurs as blue acicular crystals typically replacing the biotite and is the product of metasomatic mineral replacement reactions by dissolution–reprecipitation processes associated with Na- and Li-rich hydrothermal fluids.

Carbonates reduce the melting point of the mantle, and carbonate melts produced in low-degree melting of a carbonated mantle are considered the precursor of CO₂-rich magmas. We established experimentally the melting relations of carbonates up to 9 GPa, showing that Mg-carbonates melt incongruently to periclase and carbonate melt. The trace element signature of carbonate melts parental to kimberlites is approached by melting of Mg-rich carbonates.

Labradorite displays various structural features which have received attention in science for a long time. In this paper an electron microscopy study was performed investigating the hierarchical structure and connecting its features over several orders of magnitude. In addition, the atomic structure was solved with three-dimensional electron diffraction, showing results comparable to X-ray diffraction data and demonstrating the potential of the method to solve complicated crystal structures.

This paper describes the characterisation of a new mineral from a South Australian phosphate quarry. The characterisation included chemical analyses, infrared spectroscopy, and a determination and refinement of the crystal structure. The results showed that the mineral has a unique crystal chemistry, but it is closely related to the well-known phosphate mineral crandallite.