Heavy metal being immobilised in the lattice of a mineral is beneficial for its removal, recovery and reuse from wastewater. It is therefore essential to determine how heavy metals can be transferred into minerals controllably. This work developed a potential way for transforming heavy metals (Cu2+, Pb2+, Ni2+, Zn2+ and Cd2+) in wastewater into solids with high efficiency by introducing crystal seeds. The results of this work demonstrate that the addition of hydrotalcite and paratacamite crystal seeds can enhance heavy metal removal, both in simulated and actual acid mine wastewater. The removal rate can be increased by 18–47% and 31.8% for each heavy metal and total heavy metals in the presence of each crystal seed, respectively. Additionally, the recovery products of heavy metals can be changed by crystal seeds. In the systems without crystal seeds, the recovery products are mixtures; but the pure phase can be achieved if crystal seeds are added. For instance, in the Cu2+–Al3+–Cl– system without crystal seeds, the products were mixtures of paratacamite and layered double hydroxides (LDHs). But the products could be altered easily by hydrotalcite or paratacamite seeds. Paratacamite seeds induced Cu2+ to form paratacamite at pH 5.0, but a mixture of LDHs and paratacamite at pH 7.0. In contrast, hydrotalcite seeds induced Cu2+ to form LDHs at both pH 5.0 and 7.0. From the perspective of enthalpies of formation, CuAl-LDH and paratacamite are potential products, but the former is generally more stable, and thus it becomes the dominant product of the reaction systems using crystal seeds. It is believed that the crystal seeds can accelerate the dynamic process of LDH formation. This work suggests a controllable way for heavy metals removal, recovery and reuse.

Diamonds are found occasionally in the United States of America. Diamonds from the Prairie Creek lamproite in Arkansas, USA occur within a north to south corridor of Neoproterozoic-to-mid-Cretaceous magmatism that extends across North America. These diamond-bearing lamproites are unusual because they intrude adjacent to sutured and strongly thinned lithosphere rather than stable within-plate settings and the diamonds themselves provide physical evidence of processes related to diamond formation at the cratonic margin. Indeed, A review of previously published geophysical data, isotopic compositions, inclusion suites and inclusion geochemistry suggest most diamonds were formed in subducted and eclogitic rocks within a highly localised diamondiferous lithosphere beneath the cratonic margin.

The morphology and spectroscopic character of 155 diamonds from the Prairie Creek lamproite suggest typical diamond formation conditions in an otherwise thinned continental lithosphere. Most diamonds examined during this investigation have spectroscopic features indicating strong nitrogen aggregation, a history of thermal perturbation and plastic deformation. Nitrogen contents range up to 1882 ppm and the diamonds preserve ∼70% aggregated nitrogen in the B aggregation state. Furthermore, inclusion elastic barometry and time-averaged mantle residence temperatures suggest most Arkansas diamonds formed at 5.2±0.2 GPa and 1205±63°C (1σ). However, a subpopulation of ∼4% of relatively large and inclusion free, colourless, flattened-to-irregular habit Arkansas diamonds are Type IIa with <5 at.ppm nitrogen. Those stones size, morphology, colour and N content might warrant their inclusion in the class of Cullinan-like, Large, Inclusion-Poor, Pure, Irregular and Resorbed or ‘CLIPPIR’ diamonds. Other diamonds examined commonly exhibit physical evidence of plastic deformation, including brown body colour and deformation lamellae.

Subcalcic Cr-rich pyrope is a typical inclusion in natural diamond and considered as the main indicator mineral in diamond exploration. This article presents the results of experiments using a model garnet–spinel–harzburgite with the objective of determining the maximum Cr content of the garnet. This study supplements the existing CaO vs Cr2O3 diagram with new experimentally obtained data on Cr-rich garnets. A high-pressure apparatus (BARS) was used to conduct experiments at a pressure of 5.5 GPa and temperature of 1300°С, which corresponds to the stability field of both garnet and diamond. A model harzburgite was obtained using natural Mg-serpentine, which decomposes at the pressures and temperatures of this experiment into olivine and orthopyroxene. Natural chromite and carbonatite were used as the sources of Cr and Ca, respectively. The samples formed are composed of forsterite, enstatite, Cr-pyrope and Cr-spinel. The maximum Cr2O3 content, 16.23 wt.%, was detected in grains which grew in contact with chromite. The addition of 1–2 wt.% carbonatite resulted in the crystallisation of garnets with varying Ca contents (2.83–7.49 wt.% CaO). The experiments confirmed the boundary at 16 wt.% Cr2O3 for subcalcic pyrope associated with diamond. It is concluded that the origin of natural samples of Ca-rich lherzolitic/wherlitic and Ca-poor harzburgitic garnets with >16 wt.% Cr2O3 can be attributed to the specific Ca/Cr/Al ratios of the host medium.

Neotype material of chukhrovite-(Ce), ideally (Ca3Ce)[AlF6]2(SO4)F·12H2O, was established on the basis of a new occurrence from the Tripi mine, Alì, Peloritani Mountains, Sicily, Italy. In fact the Russian specimens originally considered as type material of this species were later found to correspond to Ce-rich chukhrovite-(Y). At the Tripi mine, chukhrovite-(Ce) occurs as white cube-octahedral crystals, up to 0.05 mm in size, associated with creedite, quartz and fluorite. Electron microprobe analysis gave (in wt.%, normalised to sum = 100.00): SO3 8.40, P2O5 0.16, ZrO2 0.12, Al2O3 11.95, Y2O3 0.48, La2O3 3.64, Ce2O3 7.63, Pr2O3 1.00, Nd2O3 3.23, Sm2O3 0.97, Eu2O3 0.13, Gd2O3 0.97, Dy2O3 0.21, CaO 20.47, F 22.09, Cl 0.07, O = (F, Cl) –9.31, H2Ocalc 27.80. On the basis of 29 anions per formula unit, assuming the presence of 13 (F+Cl+OH) atoms and 12 H2O groups, the empirical formula of chukhrovite-(Ce) from the Tripi mine is Ca3.17(Ce0.40La0.19Nd0.17Pr0.05Sm0.05Gd0.05Y0.04Eu0.01Dy0.01)Σ0.97Zr0.01Al2.04(S0.91P0.02)Σ0.93O4[F10.10Cl0.02(OH)2.88]Σ13.00·12H2O. The occurrence of H2O groups was supported by micro-Raman spectroscopy. Chukhrovite-(Ce) is cubic, Fd$\bar 3$, with a = 16.7608(5) Å, V = 4708.5(4) Å3 and Z = 8. Its crystal structure was refined to R1 = 0.0378 for 604 unique reflections with Fo > 4σ(Fo) and 36 least-square parameters. Chukhrovite-(Ce) belongs to the chukhrovite group and it is isotypic with chukhrovite-(Y), whereas it is homeotypic with chukhrovite-(Ca).

Five typical metal cations (i.e. Na+, K+, Ca2+, Mg2+ and Al3+) were selected as representatives to study the influence of metal cations on the dissolution and transformation of biotite. This work focussed on the mineralogical features of transformation products and phase transformation mechanisms by utilising modern spectroscopic methods and micro-beam characterisation techniques. In comparison with a control system, K+ inhibited the dissolution and transformation of biotite, leading to the generation of amorphous iron hydroxides on the biotite surface. Na+, Mg2+ and Ca2+ promoted the dissolution of biotite but inhibited its transformation into kaolinite, with the Na system producing sodium-bearing biotite, vermiculite, hematite and a small amount of kaolinite, and the Mg and Ca systems producing mainly vermiculite, chlorite and hematite. Al3+ notably accelerated the dissolution and transformation of biotite, resulting in well-crystallised kaolinite and hematite. Furthermore, metal cations changed the formation mechanism of kaolinite by altering the dissolution rate of biotite. Within the blank system, biotite dissolved slowly, with elements (i.e. Al and Si) accumulating on the biotite surface and growing epitaxially into kaolinite; whereas in the Al system, the rapid dissolution of biotite provided a large amount of Si, which combined with Al in the solution, forming kaolinite via a dissolution–recrystallisation process. In addition, the exchange reactions of metal-cation–K+ and the competitive adsorption of metal-cation–proton simultaneously constrained the dissolution process of biotite. This work offers a theoretical basis for an in-depth comprehension of the factors influencing biotite weathering and new insights into the evolution of clay minerals in terrestrial surface environments.

Unveiling the pressure‒temperature path of low-grade metamorphic rocks is challenging because of the occurrence of detrital minerals and high-variance mineral assemblages (i.e. chlorite–white mica–quartz). This paper is an attempt to reconstruct the pressure–temperature history on metapelites from a low-grade metamorphic unit, i.e. the Cabanaira Unit, located in the Marguareis Massif (Western Ligurian Alps, Italy). In order to obtain the most robust result possible, multi-equilibrium thermobarometry, forward modelling and crystallochemical index measurements are used together to reconstruct a pressure–temperature path, with consideration of the strengths and weaknesses of these methods.

This multidisciplinary approach allowed us to reconstruct the metamorphic evolution of the unit of interest, characterised by a pressure peak reached under low-temperature conditions (0.85–0.68 GPa and 250–285°C) followed by decompressional warming (low pressure–high temperature, 0.4-0.6 GPa and 300–335°C).

This pressure‒temperature path is consistent with the tectonic evolution of the investigated area proposed by previous studies, where a geological scenario in which the Cabanaira Unit experienced subduction-related processes was postulated, even if the reasons for warming remain unclear.

Multi-equilibrium thermobarometry is considered to be the most suitable method to unravel the metamorphic history of low-grade rocks, whereas forward thermodynamic modelling and the calculation of crystallochemical indexes seem to resolve only some segments of the pressure‒temperature path.

Members of norsethite-type carbonate solid solutions with the compositions Ba(Mg1–xMnx)(CO3)2, (x = 0, 0.25, 0.50 and 0.75) have been synthesised under high-pressure and -temperature conditions (3GPa, 800°C) for the first time. The synthetic transparent crystals gradually changed their appearance from colourless to blue lustre with the increasing Mn2+ content (XMn). The results of the crystal structure analyses reveal that the lattice parameters (a, c, unit-cell volume, Mg/Mn–O bond lengths and Ba–O bond lengths) complied with a linear increase with XMn. In contrast, the C–O bond lengths and O–C–O bond angles decreased, because the CO32– group was squeezed by the expansion of the (Mg/Mn)O6 octahedra. Moreover, the Raman and infrared vibrations, except for the lattice mode T, shift to low frequency with the increasing XMn, and the slight corresponding variations of the atomic positions were also determined. These new results demonstrate the impact of Mg2+–Mn2+ substitution on the crystal chemistry of norsethite-type solid solutions, with further implications for the natural occurrence and environmental of norsethite-type and dolomite/ankerite-type carbonates.

Nano-silicon has been regarded as the most promising anode material for next-generation lithium-ion batteries (LIBs). However, the preparation of nano-silicon suffers from high cost, complex procedures, and low yield, which hinders its commercial application. In this study, porous nano-silicon with particle sizes in the range of 50–100 nm was prepared through molten salt-assisted magnesiothermic reduction using porous nano-silica derived from clay minerals as the precursor. Through combining ball milling and acid activation, the synthesised nano-silica derived from montmorillonite exhibited smaller particle sizes (below 50 nm), higher specific surface area (647 m2 g–1), and total pore volume (0.71 cm3 g–1). This unique structure greatly facilitated the conversion efficiency of silica into nano-silicon by maximising the contact area between silica and magnesium powder and optimising the diffusion kinetics of magnesium atoms. When used as anodes in LIBs, the synthesised nano-silicon materials demonstrated a high specific capacity of up to 1222 mAh g–1 and an excellent capacity retention rate of 79% after 150 cycles at a current density of 0.5 A g–1. This method provides a novel approach for the cost-effective and large-scale production of nano-silicon materials for high-performance anodes.

The new mineral popugaevaite Ca3[B5O6(OH)6]FCl2·8H2O was found at the Internatsional’nyi diamond mine, Internatsional’naya kimberlite pipe, Sakha (Yakutia) Republic, Russia. It belongs to the low-temperature hydrothermal mineral assemblage formed in the contact zone between kimberlite and a boron-bearing halite rock. Popugaevaite occurs as veinlets in massive aggregates of ekaterinite and crusts (up to 0.7 mm thick and up to 1 cm × 4 cm in area) on ekaterinite nodules embedded in halite. Other associated minerals are Fe-rich szaibélyite, serpentine, dolomite, pyrrhotite and chalcopyrite. Crude prismatic crystals of popugaevaite are up to 0.3 × 1 mm. The mineral is transparent, colourless, with vitreous lustre and perfect {010} cleavage. It is optically biaxial (–), α 1.502(2), β 1.523(2), γ 1.530(2) and 2Vmeas = 50(10)°. The chemical composition (wt.%, electron-microprobe, boron by ICP-MS, H2O calculated by stoichiometry) is: CaO 28.54, B2O3 28.62, F 3.19, Cl 11.50, H2O 32.83, O = (F,Cl) –3.94, total 100.74. The empirical formula, calculated based on 23 O+F+Cl and 22 H atoms per formula unit, is Ca3.07B4.96O6.03(OH)6F1.01Cl1.96·8H2O. Popugaevaite is monoclinic, space group Pn, a = 8.7055(11), b = 8.1025(11), c = 14.812(2) Å, β = 91.367(7)°, V = 1044.5(2) Å3 and Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I,%)(hkl)] are: 8.12(100)(010), 4.058(27)(020), 3.577(15)($\bar 1$21), 2.936(10)(123), 2.834(16)(301, $\bar 1$05) and 2.283(10)(133). The crystal structure was solved based on single-crystal XRD data and refined on powder data by the Rietveld method, Rwp = 0.0058, Rp = 0.0043 and Robs = 0.0241. Popugaevaite is an isostructural analogue of brianroulstonite Ca3[B5O6(OH)6](OH)Cl2·8H2O with F– instead of the OH– group non-bound with boron. The structure is based upon the layers of twelve-membered rings of alternating BO3 triangles and BO2(OH)2 tetrahedra. The mineral is named in honour of the Russian geologist Larisa Anatol’evna Popugaeva (1923–1977), one of the principal discoverers of diamondiferous kimberlite pipes in Yakutia.

Different two-dimensional structural units of layered silicate minerals have different chemical and reaction properties. Sulfuric acid solution mineral-leaching systems with pH of 2.0, 4.0 and 6.0 were constructed to investigate the differential dissolution properties of lizardite (1:1 type), chlorite and talc (2:1 type minerals) and the chemical kinetic mechanism of the mineral–water interface reaction. The results showed that the dissolution efficiency of Mg in lizardite is higher than that of chlorite and talc in acidic environments (pH of 2.0, 4.0 and 6.0). The dissolution efficiency of Mg in chlorite is greater than that of talc for acidic environments when pH is 2.0 and 4.0, but chlorite and talc have nearly identical Mg dissolution efficiencies at a pH of 6.0. This phenomenon is related to the defect site on the tetrahedral sheet of chlorite and is controlled by the change of the dissolution efficiency of Al. The dissolution rates of Mg and Si in lizardite, chlorite and talc decreased with the increase of reaction time in the acidic medium for pH = 2.0, 4.0 and 6.0, and there are two linear dissolution trends at different pH values. The dissolution efficiencies of Mg and Si in lizardite, chlorite and talc were simulated and predicted by establishing a logistic model. It was found that the maximum dissolution efficiency of 2:1 type minerals chlorite and talc are only 4.72% and 1.58%, which is much lower than that of 1:1 type lizardite. This research on the reaction mechanism and dissolution kinetics of lizardite, chlorite and talc not only helps to deepen the understanding of the mineral–water interface interaction, but also reveals the different rules for Mg, Si and Al dissolution in different types of trioctahedral mineral–water interface reactions, and provides a crystal chemical basis for the ion migration and action mechanism of minerals.

Laueite/stewartite epitaxy was studied using single-crystal diffraction applied to a composite crystal from Hagendorf-Süd, Bavaria. The orientation relationships between the crystals of the two minerals was facilitated by using a non-conventional B$\bar {1}$ space group setting for stewartite, giving unit cells with parallel axes and with as = 2al, bs = bl and cs = 2cl. Face indexing of the crystals of the two minerals confirmed the epitaxial relationship, with the {100} and {010} faces parallel. The plane of epitaxy is {010}. Refinement of laueite and stewartite datasets extracted from the composite-crystal data collection showed a significant decrease in the mean Mn-site bond distances in laueite, consistent with chemical analyses of the crystals that gave site compositions of Mn0.92Fe3+0.08 for stewartite and Mn0.66Mg0.17Fe3+0.17 for laueite. The epitaxial growth of laueite on {010} planes of stewartite appears to have been initiated by a change in solution chemistry. Possible paragenesis of the secondary phosphate minerals from primary triphylite is discussed.

The sulfide-free metasomatic rocks with chalcophile metals from the Nežilovo ore field, near Veles, Republic of North Macedonia belong to a rare kind of ore. The mineralogy and petrology of these rocks were studied in detail and can be considered as a standard description for ores of this type. A characteristic feature of Nežilovo-type ores is a wide variety of accessory oxide minerals containing chalcophile elements (Zn, Pb, Sb, Cu and As). The new nolanite-supergroup mineral zincorinmanite-(Zn), ideally (Fe3+2Zn)SbZnO7(OH), was discovered in the Nežilovo ore. The associated minerals are quartz, baryte, gahnite, Zn-bearing phlogopite, together with accessory hematite, almeidaite, a Pb-analogue of hydroxycalcioroméite and an insufficiently studied Sb-rich högbomite-supergroup mineral. Zincorinmanite-(Zn) forms lamellar to tabular subhedral single-crystal grains up to 0.5 mm across and up to 40 μm thick. The colour and streak are black and the lustre is submetallic. The new mineral is brittle, with the Mohs’ hardness of 6. No cleavage is observed. The fracture is uneven. The calculated density is 5.446 g·cm–3. In reflected light, zincorinmanite-(Zn) is light grey, no pleochroism is observed. The reflectance values (Rmin, %/Rmax, %/λ, nm) are: 12.6/13.7/470, 12.1/13.2/546, 11.8/12.8/589 and 11.5/12.2/650. The Raman spectrum shows bands corresponding to the O–H and Sb–O stretching vibrations and (Fe3+,M2+)–O–H bending modes. The chemical composition is (electron microprobe data, with iron divided into Fe2O3 and FeO based on the charge balance and H2O calculated from the structural data, wt.%): MgO 1.42, MnO 0.44, FeO 2.04, ZnO 22.55, Al2O3 1.95, Fe2O3 35.59, TiO2 1.51, Sb2O5 33.05, H2O 1.18, total 99.73. The empirical formula is [(Fe3+2.12Al0.18)(Zn0.32Mg0.16Fe2+0.13Mn0.03)Ti0.06]Σ3.00(Sb0.97Ti0.03)Σ1.00Zn1.00O7[(OH)0.61O0.39]Σ1.00. The crystal structure was determined using single-crystal X-ray diffraction data and refined to R = 0.0191. Zincorinmanite-(Zn) is hexagonal, space group P63mc, a = 5.9720(1), c = 9.3578(1) Å and V = 289.031(8) Å3 (Z = 2). The new mineral is isostructural with other members of the nolanite group. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) – hkl] are: 5.176 (46) – 100; 3.473 (77) – 102; 2.989 (46) – 110; 2.674 (86) – 103; 2.520 (100) – 112; and 2.496 (42) – 201.

In the soil environment, divalent heavy metal ions often interact with trivalent metal ions to form hydrotalcite supergroup nanominerals (also known as natural layered double hydroxides, LDHs), effectively immobilising heavy metals within the minerals structure. Concurrently, these LDH minerals also show high surface reactivity and can adsorb surrounding heavy metal ions, thus they play a significant role in heavy metal pollution purification. However, the impact of the subsequent geochemical evolution of heavy-metal-containing LDHs on the migration and transformation of structural and surface-adsorbed heavy metals as well as its surface reactivity towards surrounding heavy metals remains unclear. Herein, Ni(II)Fe(III)-LDH and Co(II)Al(III)-LDH were taken as examples to reveal the influence of redox evolution on the immobilisation of structural and adsorbed heavy metals. The results of this work indicate that the oxidative–reductive alternating evolution of structural Ni, Fe and Co elements constrain the transformation of heavy metals, as well as their bioavailability greatly. The oxidative–reductive alternating evolution helped reduce the content of bioavailable heavy metals in exchangeable and carbonate-bounded states. It can also enhance the integration of heavy metals with the LDH structure and help transform heavy metals into residual states, thereby reducing their mobility and bioavailability. However, oxidative–reductive evolution significantly reduced the surface reactivity of LDHs, diminishing their interface locking ability for surrounding heavy metal ions. This research provides foundational data for assessing the long-term environmental performance of LDHs.

Ferrodimolybdenite with ideal formula FeMo3+2S4 (C2/c, a = 11.8249(8) Å, b = 6.5534(3) Å, c = 13.0052(10) Å, β = 114.474(9)°, V = 917.27(12) Å3 and Z = 8) was discovered in a differentiated sulfide nodule composed of troilite and pentlandite parts. The nodule was detected in the central zone of a diopside–anorthite–tridymite oval paralava body, ∼30 metres in diameter, within the pyrometamorphic Hatrurim Complex in Daba-Siwaqa, Jordan. Ferrodimolybdenite is the first trivalent molybdenum compound discovered in Nature. Its synthetic analogue crystallises in the C1c1 space group. Ferrodimolybdenite with the empirical formula (Fe2+0.99Cu2+0.07Ni2+0.04)Σ1.10Mo3+1.94(S2–3.98P3–0.02)Σ4.00 was identified in the troilite part of the differentiated sulfide nodule. The nodule contains inclusions of tetrataenite, nickelphosphide, molybdenite, galena and rudashevskyite. Ferrodimolybdenite forms platy crystals with dimensions ranging from 3×100 μm to 20×40 μm. The mineral exhibits a grey colour and a dark grey streak. It is opaque with a metallic lustre, and its Mohs hardness is ∼3. The cleavage observed in the mineral is perfect on {001}, good on {100} and poor on {010}. Its tenacity is sectile, and its fracture is smooth. The calculated density of 5.445 g·cm–3 was derived from the empirical formula and unit cell volume refined from single-crystal X-ray diffraction data. In reflected light, ferrodimolybdenite appears grey to light grey with a blueish tinge. It is anisotropic, with a reflectance in the range of 34–40%. The crystallisation of ferrodimolybdenite occurred in reduced conditions in monosulfide Fe(+Ni) melt at a temperature of 1000–1100°C and at low pressure.

Barium- and Ca-rich stronalsite [ideally SrNa2Al4Si4O16] occurs rarely as pseudomorphs, which are probably after nepheline, and is found in hydrothermally altered Sr-enriched leucocratic dykes or streaks hosted by mesocratic amphibole–pyroxene teschenite in the Silesian Unit (Flysch Belt of the Western Carpathians, Czech Republic). In addition to stronalsite, the pseudomorphs consist of slawsonite, celsian, biotite, muscovite, alkali feldspar, natrolite and thomsonite-Ca. The surrounding groundmass is rich in alkali feldspars and zeolites and sporadically also contains amphibole phenocrysts, chloritised biotite, fluorapatite and other accessory and/or secondary minerals. Both compositional types of stronalsite have identical Raman spectra. The Ba-rich stronalsite contains 0.55–0.83 apfu Sr, 0.12–0.37 apfu Ba, and <0.08 apfu Ca. In contrast, Ca-rich stronalsite contains 0.65–0.82 apfu Sr, 0.10–0.23 apfu Ca, and <0.06 apfu Ba. The substitution mechanisms by which Ca enters the structure of stronalsite could not be satisfactorily clarified from the available data; the best stoichiometric fit suggests for substitution of Sr, which should not be possible due to the different crystal structure of the Ca-analogue of stronalsite, lisetite [ideally CaNa2Al4Si4O16]. The Na contents range is 1.82–2.42 apfu and the K contents are consistently low (<0.09 apfu). The T site contains 3.91–4.26 apfu Si, 3.76–4.00 apfu Al and 0.00–0.11 apfu Fe3+. The main source of Sr was probably primary magmatic plagioclase that underwent hydrothermal alteration by post-magmatic high-temperature brines mixed with fluids of external origin. On the basis of previous research and paragenetic relationships, we estimate that stronalsite crystallised at T ∼250–320°C and P <100 MPa.

Parisite-(Nd) (IMA2024-013), ideally CaNd2(CO3)3F2, as the Nd-dominant analogue of parisite-(Ce), occurs in dolomitic marble in the Bayan Obo Fe–Nb–REE deposit, Inner Mongolia, China. It is associated with calcite, aegirine, magnetite, hematite, fluorite, riebeckite, bastnäsite-(Ce), baryte, aeschynite-(Ce), aeschynite-(Nd), monazite and parisite-(Ce). Parisite-(Nd) occurs as subhedral to anhedral irregular grains from 0.02 mm to 1 mm. Parisite-(Nd) is transparent, yellowish-brown colour, with pale yellow streak and displays vitreous to resinous lustre. Cleavage is distinct on pseudo-{001}; fracture is uneven, or conchoidal. The Mohs hardness is 4 to 5, and it is brittle. The calculated density of parisite-(Nd) is 4.357 g/cm3. Parisite-(Nd) is pseudo-uniaxial (+), ω = (1.679) and ε = (1.754). The empirical formula is (Ca0.945Fe0.058Sr0.015Ba0.007)Σ1.025(Nd0.967Ce0.529La0.191Pr0.137Gd0.070Sm0.029Th0.022Y0.016Nb0.011Ho0.003)Σ1.975(CO3)3F1.893OH0.023. The Raman spectra of parisite-(Nd) show strong and sharp peaks at 1113, 1090, 825, 635 and 1608 cm–1 and moderate to weak bands centred at 255, 392, 739, 924, 1183, 1228, 1296, 1640, 2247, 2924 and 3065 cm–1. Powder X-ray diffraction and TEM studies give the following results: monoclinic, space group: Cc (# 9), a = 12.3283(13) Å, b = 7.1185(4) Å, c = 28.4633(37) Å, β = 98.529(14)°, V = 2470.28(42) Å3 and Z = 12.

The new mineral manganonewberyite (IMA2024–004), Mn(PO3OH)(H2O)3, was found underground at the Cassagna mine, Liguria, Italy, where it is a secondary phase formed by the interaction of bat guano with Mn-rich rock. Manganonewberyite occurs with niahite, kutnohorite, sampleite and serrabrancaite on a tinzenite–quartz–braunite matrix. Crystals are prisms and blades, up to ∼0.15 mm long, elongated parallel to [001], flattened on {100} and exhibiting the forms {100}, {010} and {111}. Crystals are colourless and transparent, with vitreous lustre and white streak. The mineral is brittle with curved fracture. The Mohs hardness is ∼3. Cleavage is perfect on {010}. The density is 2.34(2) g·cm–3. Optically, manganonewberyite is biaxial (+) with α = 1.541(2), β = 1.547(2) and γ = 1.559(2) (white light). The 2V is 71.6(3)°. The optical orientation is X = a, Y = b and Z = c. The empirical formula is (Mn0.960Mg0.016Ca0.015)Σ0.991(H1.02P1.00O4)(H2O)3. Manganonewberyite is orthorhombic, space group Pbca, with cell parameters: a = 10.4273(6), b = 10.8755(8), c = 10.2126(4) Å, V = 1158.13(11) Å3 and Z = 8. The crystal structure (R1 = 2.79% for 892 I > 2σI reflections) is the same as that of newberyite with Mn in place of Mg.

The environmental effects of nanoparticles have attracted widespread attention. The removal and recycling of nanoparticles are crucial for both environmental protection and resource reuse. However, current removal and recycling methods are not yet mature, and there is a need to explore inexpensive materials for the efficient removal and recycling of nanoparticles. This study investigates the effects of pyrite species, thermal modification temperature, pH and ionic strength on the adsorption of gold nanoparticles (AuNPs) by pyrite. The experimental results demonstrate that the adsorption rate of artificially thermally modified pyrite is slightly faster than that of naturally thermally modified pyrite. However, the concentration of Fe ions dissolved from the artificially thermally modified pyrite is higher. Natural pyrite, when thermally modified at 400°C and 500°C, adsorbs 100% of AuNPs within 10 min. The lower the acidity of the system, the faster the adsorption rate. Conversely, an increase in ionic strength decreases the adsorption rate. Artificially thermally modified pyrite primarily adsorbs AuNPs through electrostatic gravitational attraction, which is supplemented by a significant amount of chemisorption. After four recycling cycles, the adsorption and desorption rates of AuNPs using artificially thermally modified pyrite were 92.1% and 94.2%, respectively, indicating excellent adsorption and recovery performance. The results of this study provide a new method for the recycling of nanoparticles and an experimental basis for the further application of thermally modified pyrite in environmental treatments.

A rare silver mineral, dervillite (ideally Ag2AsS2), has been found in specimens from the famous Jáchymov mining district, Czech Republic. It occurs as very rare long-prismatic crystals up to 0.4 mm across in association with proustite, bismuth and native silver in the thin arsenic veinlets within the Trojická vein (Svornost mine). Dervillite is monoclinic, space group Pc, with a = 9.6375(3), b = 12.9462(4), c = 6.8497(2) Å, β = 99.510(2)° and V = 842.88(2) Å3 (Z = 8). The new structure refinement, R1 = 2.94% for 18767 reflections with [I > 3σ(I)] and wR2 = 7.93% for all 20050 reflections, provided a better fit to the data compared to earlier studies, revealing that silver (8 symmetrically independent atomic sites), which adopts various coordinations (from quasi-linear to tetrahedral) in the structure of dervillite vibrates non-harmonically at room temperature. The Gram-Charlier development, describing the atomic displacement parameters of silver atoms, was used to model their non-harmonic behaviour. A discussion on the use of the approach to the data with limited quality is also provided.

The Diely occurrence of metamorphosed As-rich manganese mineralisation is located in the Spišsko-gemerské rudohorie Mountains near the Poráč village and comprises Early Palaeozoic metamorphic rocks of the Gemeric Unit in the Western Carpathian region. Mineralisation is situated in the narrow tectonically delineated belt of Rakovec Group rocks consisting of mafic metavolcanic material generated during the back-arc submarine volcanic activity of the Early Ordovician–Silurian period. The Mn mineralisation is hosted in siliceous laminated lenses (metacherts) embedded in metabasalts and its tuffs. Manganese ore consists of quartz, braunite, rhodonite, nambulite, rhodochrosite, kutnohorite, OH-bearing garnets with dominant andradite composition, hematite, aegirine, aegirine–augite, ferri-ghoseite, ferri-winchite, baryte and pyrophanite. The mineralisation is cross-cut by a system of narrow younger veins composed dominantly of As-enriched minerals of the pyrosmalite group (schallerite, mcgillite and friedelite), tiragalloite, manganberzeliite, brandtite, sarkinite and svabite, associated with hematite, rhodochrosite, kutnohorite, baryte and quartz. Formation of manganese mineralisation at the Diely occurrence was caused by migration of seawater into the basaltic oceanic crust where increasing temperatures and acidity generated hydrothermal fluids enriched in manganese. The Mn-bearing hydrothermal fluids were enriched in Li, providing an additional substituent in the mineralisation. Following initial stages, the subsequent Variscan and Alpine tectonometamorphic events resulted in formation of three main mineralisation stages distinguishable by paragenetic relations and the mineral composition. Based on metamorphic association and amphibole geobarometric calculations, the peak metamorphic conditions reached was upper greenschist facies. The Diely occurrence near Poráč represents a unique metamorphosed manganese mineralisation with abundant arsenates and arsenosilicates previously unknown in the Western Carpathian region.