Experimentally, silica activity (aSiO2) has been shown to have an effect on Mg diffusion in forsterite, but no fully satisfactory mechanism has yet been proposed. We calculated the effects of aSiO2 and aluminium content (the main contaminant in some recent experimental studies), and their co-effect, on Mg diffusion in forsterite, using thermodynamic minimisations of defect formation energies [calculated

The previously unknown crystal structure of pingguite was determined and refined from laboratory X-ray powder diffraction data using a synthetic sample. Additional single crystal diffraction of natural pingguite confirms that the crystal structure of the synthetic sample is identical to the natural mineral. This new crystal structure calls for a revised chemistry of the rare mineral pingguite to B

The present work reports the crystal-chemical characterization of micas from the Monte Arsiccio and Buca della Vena mines (Apuan Alps, Italy) through electron microprobe analysis, single-crystal X-ray diffraction, and Raman spectroscopy. The sample from the Monte Arsiccio mine can be classified as an intermediate member of the yangzhumingite-fluorophlogopite series, with average crystal-chemical formula

We performed deformation experiments on dry natural single crystals of magnetite and ilmenite to determine the rheological behavior of these oxide minerals as a function of temperature, orientation, and oxygen fugacity. Samples were deformed at temperatures of 825–1150 \(\,^{\circ }\)C to axial strains of up to 15–24% under approximately constant stress conditions up to 120 MPa in a dead-load-type

Core-level and valence-band X-ray photoelectron spectroscopy was employed to study the dose-dependent radiation effects in the short-range order and the electronic structure of natural U, Th-bearing zircon near-surface layers. Single crystals from different localities (Ratanakiri, Cambodia; Mud Tank, Australia; Highlands, Sri Lanka) exhibiting wide variations in the accumulated radiation dose D≈(0 ÷ 9

The high-pressure behaviour of meyerhofferite [ideally Ca2B6O6(OH)10·2(H2O), with a ~ 6.63 Å, b ~ 8.34 Å, c ~ 6.47 Å, α = 90.8°, β = 102°, γ = 86.8°, Sp. Gr. P\(\overline{1}\)], a B-bearing raw material (with B2O3 ≈ 46 wt%) and a potential B-rich aggregate, has been studied by single-crystal synchrotron X-ray diffraction up to 9 GPa, under hydrostatic conditions. Meyerhofferite undergoes a first-order

The new crichtonite-group mineral saranovskite, ideally SrCaFe2+2(Cr4Ti2)Ti12O38, was discovered in the Glavnoe Saranovskoe deposit, Middle Urals, Russia, and named after the type locality. The associated minerals are chromite, Cr-bearing clinochlore, and calcite. Saranovskite forms black crude equant crystals about 2 mm across. The lustre is submetallic, and the streak is brownish-gray. Cleavage is

The structural parameters and the thermal behavior of a complete series of Ca–Mg carbonates synthesized at high pressure and temperature (1–1.5 GPa, 1273–1373 K) in the range 0–50 mol% MgCO3 have been investigated by in situ powder synchrotron high-resolution X-ray diffraction at ambient and up to 1073 K under self-controlled CO2 partial pressure. The crystal structures are disordered Mg calcite in

The influence of mole fraction and nature of the cations in positions [8]A and [6]B of the pyrochlores containing Na+, Ca2+, Cd2+, U4+, Nb5+, Ta5+, Ti4+, Sb5+, Zr4+, V3+, V4+, W5+, W6+ synthesized under hydrothermal conditions at 800 °C, 200 MPa and controlled oxygen fugacity in NaF solution of 1.0 mol·kg−1 H2O on lattice parameters has been considered. The unit cell parameters of the fluorpyrochlores

Natural radiation-induced red fluorescence of fluorite consists of two broad bands at 750 and 635 nm with very short decay times of 20.3 and less than 5 ns, respectively. The first one is connected to an M center compensated by Na, while the second is connected to an M+ center, possibly formed as result of the M center’s destruction by UV irradiation. The optically active centers in naturally irradiated

The elastic behavior of low albite is investigated ab initio under hydrostatic pressure up to 16 GPa. Our calculations complement and extend previous studies confirming a highly anisotropic character of the feldspar cell compression and, more importantly, revealing a clear change of all structure deformation trends around 8–9 GPa pressure. We correlate this change to the trend of the bulk modulus of

Three new borate minerals rhabdoborite-(V), rhabdoborite-(Mo) and rhabdoborite-(W), forming the rhabdoborite group, are found in the Arsenatnaya fumarole, Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. They are closely associated with each other and anhydrite, diopside, hematite, schäferite, berzeliite, svabite, calciojohillerite

In the present work, the oxidation and spin state of Fe and the local structure around Fe in the supercapacitor birnessite with different contents of the Fe dopant were investigated using Mössbauer spectroscopy. It was found that Fe ions were exclusively present as high spin Fe3+ in octahedral coordination with about 70% iron occupying the Mn3+ positions and about 30% iron occupying the Mn4+ positions

We report in this paper a new crystal-chemical study of synthetic basic ferric sulfate FeOHSO4. The structure solution performed by the Endeavour program, from new X-ray powder diffraction (XRPD) data, indicated that the correct space group of the monoclinic polytype of FeOHSO4 is C2/c. Selected Area Electron Diffraction (SAED) patterns are also consistent with this structure solution. The arrangement

The high-pressure behavior of manganese diselenide MnSe2 was investigated by synchrotron angle-dispersive X-ray diffraction (ADXRD) and infrared reflection spectroscopy equipped with a diamond-anvil cell. It was found that MnSe2 with a pyrite-type structure undergoes a transformation into a disordered intermediate phase at ~ 12.5 GPa, with a ground state composed of an arsenopyrite-type structure,

The valence and spin states of Fe in (Fe,Al)-bearing bridgmanite (bdg) affect its physical properties, which is important for the interpretation of geophysical observations. Currently, tens of studies on the compressibility and spin states of Fe-bearing bdg have been reported. A consensus is that Fe-bearing bdg shows spin transition, which affects its elastic parameters. However, there is a conflict

Metal halide perovskites have attracted great attention in the past decade due to unique and tunable optical and electrical properties, which are promising candidates for various applications such as solar cells, light-emitting diodes, and laser cooling devices. For cubic perovskites, the lattice constant, a, representing the size of the unit cell, has a significant impact on the structural stability

The free energy of binding between a cation vacancy and charge-balancing tetravalent cation in MgO is calculated from molecular dynamics simulations, at temperatures of 1200–2400 K and pressures of 0–25 GPa. The entropy of binding, obtained from the temperature dependence of the binding free energy, is found to be independent of pressure and to have a value of 13(5) J/mol K (2σ). The binding volume

Phase relations of NaAl3Si3O11 and NaAlSi3O8 were explored at pressures of 20.5–23.5 GPa and temperatures of 2373 and 2573 K by multianvil experiments. For NaAl3Si3O11, a new phase, which is tentatively named NAS phase, was obtained at 22.5 GPa, 2373 and 2573 K and also at 23.5 GPa, 2573 K. NAS phase was found to be isostructural to CaAl4Si2O11 (CAS) phase, but have smaller lattice parameters. The

A new alluaudite-group mineral zincobradaczekite, a Zn–Cu ordered highly zincian analogue of bradaczekite, was discovered in sublimates of the Yadovitaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with bradaczekite, lammerite, lammerite-β, borisenkoite, mcbirneyite, sanidine, hematite

We present a model for multicomponent diffusion in ionic crystals. The model accounts for vacancy-mediated diffusion on a sub-lattice and for diffusion due to binary exchange of different ionic species without involvement of vacancies on the same sub-lattice. The diffusive flux of a specific ionic species depends on the self-diffusion coefficients, on the diffusion coefficients related to the binary

The pressure dependence of the polarized Raman scattering of quartz was studied under hydrostatic conditions up to 9 GPa. We extended the available pressure calibrations, usually limited to the two most intense peaks, to a larger number of modes, providing polynomial functions that describe the relationship between pressure P and wavenumber shift \(\Delta \omega\) for the 128-, 206-, 265-, 464-, 696-

The kinetics of serpentinization were investigated at 400–500 °C and 3.0–20 kbar using natural olivine and peridotite for run durations of 9–38 days. The serpentine varieties were lizardite for all the experiments. The serpentinization kinetics at 400 °C and 3.0 kbar and at 500 °C and 20 kbar displayed a sigmoidal kinetic behavior, with very sluggish reaction rates at the early stage of serpentinization

The thermodynamics of the system Fe–Si–O under high pressure (P) and temperature (T) was examined, starting with modelling the phase transition between a face-centred cubic (fcc) and hexagonal close-packed (hcp) structure in Fe–Si alloy which was previously examined by experiment under high P–T conditions. The mixing properties of Fe and Si for the iron phases were found to be approximated by ideal

Natural diamond remains the source of many interesting effects and finds that are difficult to reproduce or detect in synthetic crystals. Herein, we investigate the photoluminescence (PL) of more than 2000 natural diamonds in the range 800–1050 nm. PL spectra were registered with excitation at 405, 450, 488 (Ar+), and 787 nm. The investigation revealed several systems that were not previously described

We used atom probe tomography to complement electron microscopy for the investigation of spinodal decomposition in alkali feldspar. To this end, gem-quality alkali feldspar of intermediate composition with a mole fraction of \(a_{\text {K}}=0.43\) of the K end-member was prepared from Madagascar orthoclase by ion-exchange with (NaK)Cl molten salt. During subsequent annealing at \(550\,^\circ \hbox

Three non-metamict chevkinite-subgroup minerals, space group P21/a, from Cape Ashizuri, Japan, (No. 1), Tangir Valley, Diamar District, Pakistan (No. 2) and Haramosh Mts., Skardu district, Pakistan, (No. 3) were studied by crystal chemical techniques. Powder X-ray diffraction and transmission electron microscopic observations confirmed well crystalline samples. Electron-microprobe analyses indicated

The sound velocities (compressional wave velocity [VP] and shear wave velocity [VS]) of four types of aluminosilicate glasses (Mg3Al2Si6O18 (MAS), Ca3Al2Si6O18 (CAS), Na3AlSi3O9 (NAS), and K3AlSi3O9 (KAS)) are measured using the ultrasonic technique at high pressures of up to 7.8 GPa. The VP and VS of MAS glass decrease up to a pressure of 2 GPa and subsequently increase with increasing pressure. The

Amphiboles, containing up to 2 wt% water in the form of hydroxyl units, contribute significantly to water transport into the deep lithosphere and upper mantle in subduction zones, where dehydration reactions make the water available for metasomatic processes and flux melting of the overlying mantle wedge. Here, we investigate the high-pressure and temperature behavior of the calcic end-member amphibole

The study addresses the topic of fine-structural compression behaviour of solids. MgO / periclase and polyethylene / PE are studied as exemplary materials by volumetric and ultra-sound techniques at room temperature up to 1.5 GPa. The experiments conducted with a high-pressure device of the piston cylinder type rely on: (a) measurements of the piston displacement performed under continuously changing

A black tourmaline sample from Seagull batholith (Yukon Territory, Canada) was established to be a schorl with concentrations of Fe2+ among the highest currently found in nature (FeOtot ~ 18 wt.% and Fe2+ ~ 100% of Fetot) on the basis of a multi-analytical characterization through Mössbauer spectroscopy, electron microprobe, Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry and single-crystal

In this study, we present the first systematic dataset on natural variations of OH defect and trace element contents in quartz within igneous bodies. Samples were derived from bore holes of two plutonic bodies from the Krušné Hory/Erzgebirge (German-Czech border), representing typical A-type (Cínovec/Zinnwald granite cupola) and S-type (Podlesí Stock) granite intrusions. Fourier Transform Infrared

High-temperature Raman spectra of natural sillimanite, andalusite and kyanite were measured in the temperature range of 296–1273 K at ambient pressure. No phase transition was observed over the temperature range in this study. Raman modes for the three samples vary with temperature linearly. The temperature and pressure dependence of the force constants for Si–O stretching vibrations in Al2SiO5 polymorphs

Behaviour of hingganite-(Y), Y2□Be2Si2O8(OH)2, on compression to 47 GPa has been studied by synchrotron-based in situ high-pressure single-crystal X-ray diffraction at room temperature in a diamond anvil cell. In the studied pressure range no obvious phase transitions have been observed. The compression of hingganite-(Y) crystal structure is anisotropic, with b axis showing the maximal compressibility

Sanidine is an important crustal mineral whose high-pressure phase, liebermannite, can be carried down to the mantle transition zone by the subducting slab. Owing to the characteristic channel structure of liebermannite, which can provide a pathway for K+ along the [001] direction, it can serve as a highly conductive phase. In this study, we measured the electrical conductivity of natural sanidine

New spectroscopic data were obtained to distinguish the specific features of brown and pink diamonds from Internatsionalnaya kimberlite pipe (Siberian craton). It is shown that pink and brown samples differ markedly in the content and degree of aggregation of nitrogen defects. Pink diamonds generally have higher nitrogen content and a lower aggregation state compared to brown samples, which often show

This work was undertaken to investigate whether physical data exhibit any tendencies spanning the whole mineralogical system. The chemical compositions of 4973 minerals was projected into two variables, Qual_4 and InfEnt, the first a function of the atomic numbers of elements present, the second, an indication of complexity of their stoichiometry. As the Z coordinates served density (1933 minerals

Manaevite-(Ce), a new vesuvianite-group mineral has been investigated by means of electron microprobe, TGA and DSC and CHN analysis of H2O, powder X-ray diffraction, single-crystal X-ray structure analysis, 139La NMR, 57Fe Mössbauer spectroscopy, IR spectroscopy and optical measurements. Tetragonal unit-cell parameters are a = 15.9247(13) Å, c = 11.9661(10) Å, space group P4/nnc. The structure model

The new mineral borisenkoite Cu3[(V,As)O4]2 was found in sublimates of the Yadovitaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Associated minerals are sanidine, hematite, lammerite, lammerite-β, bradaczekite, zincobradaczekite, mcbirneyite, pseudolyonsite, lyonsite, starovaite, tenorite, rutile, tripuhyite

In recent years, infrared radiation materials have received extensive attention. In this study, a kind of natural carbonate rock was highlighted and its radiation mechanism investigated, using a series of mineralogical and spectroscopy studies such as optical microscope, varying-temperature X-ray diffraction (XRD), Raman spectroscopy, X-ray fluorescence spectrometer (XRF), inductively coupled plasma

Calculations using the density-functional theory (DFT) in combination with the single defect method were carried out to determine the heat of mixing behaviour of mineral solid solution phases. The accuracy of this method was tested on the halite-sylvite (NaCl-KCl) binary, pyrope-grossular garnets (Mg3Al2Si3O12-Ca3Al2Si3O12), MgO-CaO (halite structure) binary, and on Al/Si ordered alkali feldspars

The neon diffusion behavior in goethite has been investigated for the purpose of geological (U-Th)/Ne dating, as Ne produced in goethite by nucleogenic reactions related to natural U and Th alpha decay can diffuse out of the crystal. According to previous works, a multi-scale computational approach combining Density Functional Theory studies at the atomic scale and Kinetic Monte Carlo simulations at

Bastnaesite (Ce0.50La0.25Nd0.20Pr0.05)CO3F is an interesting pattern family of (CO3)2− and F− co-existing phases, which is a meaningful sample to study the influence of multiple volatiles on minerals. Thermal stability of bastnaesite has been investigated by thermogravimetric experiment and in situ high-temperature Raman. The results demonstrate that bastnaesite undergoes a decarbonization transition

We present the results of a high-pressure semi-hydrostatic study of two plagioclase minerals, andesine and albite, using diamond anvil cells (DACs) to characterize in situ variations in Raman spectra under different static pressures. In this work, we also examined the kinetic effects on deformation at both long and short timescales through non-traditional experiments in which the DAC was either dropped

MgO makes up about 20% of the Earth’s lower mantle; hence, its rheological behaviour is important for the dynamics and evolution of the Earth. Here, we investigate the strength of twin boundaries from 0 to 120 GPa using DFT calculations together with structure prediction methods. As expected, we find that the energy barrier and critical stress for shear-coupled migration of the 310/[001] interface

The structure of liquid silicates is commonly described as a statistical mixture of various atomic entities with relative abundances that can vary with pressure, temperature, and composition. Unfortunately, this view remains largely theoretical due to scarce experimental reports on the silicate melt structure, in particular under pressure. We performed X-ray diffraction of the SiO2 end member to probe

We conducted Vickers indentation tests on Fe-free (Mg2SiO4) and Fe-bearing (Mg1.8Fe0.2SiO4) olivine single crystals and high-density polycrystalline material with average grain sizes ranging from 170 to 890 nm. The Vickers microhardness (\(H_{{\text{v}}}\)) of the Fe-free polycrystalline material with the finest grain size is ~ 17 GPa at a load of 0.1 N, while that of the Fe-bearing single crystal

To explain the anomalous anisotropy in thermal expansion properties reported in rhodochrosite (MnCO3) previously Rao and Murthy (J Mater Sci 5: 82, 1970), Li et al. (High Temp High Press, 2019), the evaluation of crystal structure is thought to be indispensable as an important aspect in mineralogy. In this spirit, single crystals of impurity-free rhodochrosite, up to 100 μm in size, were synthesized

The new mineral giacovazzoite, K5Fe3+3O(SO4)6(H2O)9·H2O, has been discovered in the Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. It occurs as orange–brown prismatic crystals, up to 0.1 mm long, with yellowish streak and vitreous luster. It is brittle, with a perfect {100} cleavage. Associated minerals are alum-(K), gypsum, krausite, magnanelliite, and scordariite. Electron microprobe analysis (WDS

This paper reports on the cathodoluminescence (CL) emission of kamphaugite-(Y) (CaY(CO3)2(OH)·H2O) and kristiansenite [Ca2ScSn(Si2O7)(Si2O6OH)] that display very complex spectra. The carbonate sample, growing in spheres no longer than 3 mm, contains significant concentrations of REE giving rise to sharp and narrow wavebands peaked at 312, 486, 546, 574 and 626 nm. These wavebands would be, respectively

Natural fluorite, anhydrite and apatite under deep UV excitation exhibits several narrow emission bands in the spectral range of 225–300 nm with the strongest peaks at 230–240 nm and 260–290 nm and with half-widths of 20–30 nm. They are characterized by narrow excitation band peaking at 220 nm and very short decay times of 20–50 ns. Those spectral-kinetic parameters enable their interpretation as 4f5d–4f

Chemical compositions and crystal structures of coexisting wadsleyite, clinopyroxene, and phase E (synthesized at 1400 °C and 18 GPa under hydrous conditions) have been analyzed by electron microprobe, single-crystal X-ray diffraction, and Raman spectroscopy. Single-crystal X-ray diffraction analyses indicate that Fe2+ substitution in the crystal structure significantly decreases the configurational

In recent years, despite significant progress in the development of new methods for the synthesis of diamond crystals and in their post-growth treatment, many questions remain unclear about the conditions for the formation and degradation of aggregate impurity nitrogen forms. Meanwhile, they are very important for understanding (evaluating) the origin, age, and post-growth conditions of natural diamonds

Abstract Halamishite, Ni5P4, is a new natural phosphide discovered in pyrometamorphic assemblages of the Hatrurim Formation (Mottled Zone), Southern Levant. The mineral occurs as minute grains up to 20 μm in size intimately intergrown with zuktamrurite, FeP2, and transjordanite, (Ni,Fe)2P, which are disseminated in fine-grained diopside microbreccia. Chemical composition of the holotype material (electron

The influence of pentavalent arsenic and phosphorus on crystal chemical features of the feldspar framework was studied on the minerals belonging to the sanidine–filatovite solid-solution series from fumarolic exhalations of the Tolbachik volcano (Kamchatka, Russia). The reported feldspars demonstrate the first example of natural continuous solid solution between silicate and arsenate. The content of

The Mössbauer, infrared and Raman spectra of iron-rich oxyphlogopite from a new locality, the Bartoy occurrence, Transbaikalia, Russia were obtained and its crystal structure was solved. The mineral is characterized by the absence of OH groups and ordered distribution of Fe2+ and Fe3+ between sites having octahedral coordination. Unlike oxyphlogopite holotype sample which is monoclinic (1M polytype)

The structures of Ti-bearing anhydrous phase B and superhydrous phase B synthesized at 12 GPa/1600 °C and 21 GPa/1600 °C, respectively, have been determined by single-crystal X-ray diffraction. Anhydrous phase B has space group Pmcb. The structure of superhydrous phase B was refined in space groups Pnnm and Pnn2; crystallographic arguments unambiguously indicated that the centrosymmetric space group

Samples of calcium titanate perovskite (CaTiO3) substituted with variable amounts of trivalent La, Pr, Nd or Sm were synthesized by solid-state reaction. The synthesized compounds were characterized by means of electron microprobe (EMPA), powder X-ray diffraction and µ-Raman spectroscopy. The incorporation of the studied lanthanides in the CaTiO3 perovskite leads to the formation of complex (Ca1-2xLn2x)(Ti1-xCax)O3

The structural behaviour of cassiterite (SnO2), pyrolusite (MnO2) and sellaite (MgF2), i.e. AX2-minerals, has been investigated at room temperature by in situ high-pressure single-crystal diffraction, up to 14 GPa, using a diamond anvil cell. Such minerals undergo a ferroelastic phase transition, from rutile-like structure (SG: P42/mnm) to CaCl2-like structure (SG: Pnnm), at ≈ 10.25, 4.05 and 4.80

Diopside (\(CaMgSi_{2}O_{6}\)), the Ca- and Mg-rich clinopyroxene is an important mineral in the Earth’s upper mantle and subducted lithospheric plate. Here, we report the results of high-pressure single-crystal X-ray diffraction experiments conducted on a natural aluminous iron-bearing diopside and a natural, nearly end-member diopside, up to 50 GPa in diamond anvil cell. Density functional theory