Band 110, Heft 5

The small ionic radius of lithium ions (Li + = 0.6 Å) poses a significant challenge in visualizing and quantifying their presence within the lepidolite lattice. Nevertheless, the use of spherical aberration-corrected transmission electron microscopy (AC-TEM) in conjunction with electron energy loss spectroscopy (EELS) offers an innovative approach to surmount this challenge. In this investigation, we conducted a comprehensive analysis of lepidolite samples obtained from lithium-rich pegmatites in the Shaliuquan region of the Quanji Massif, situated at the northwestern periphery of the Qinghai-Tibetan Plateau in north-west China. Utilizing AC-TEM in tandem with EELS, we captured sub-angstrom images revealing the presence and spatial distribution of lithium atoms within the lepidolite lattice. Additionally, we quantified their concentrations and determined the formula for lithium-rich mica. This study solves a long-standing problem regarding the accurate determination of lithium concentration and showcases the viability of AC-TEM-EELS for both visualizing and quantifying lithium within the lepidolite lattice.Our finding facilitates the differentiation of cation ordering, polytypes, and lepidolite’s chemical compositions, which is helpful for advancing lithium extraction techniques and constraining the forming process of pegmatites.

X-raymicro-computed tomography (micro-CT) has been used in the geosciences to visualize the spatial arrangement of minerals and pores within rock samples. It is a powerful technique that can potentially be used to analyze lithium minerals as well, owing to its unique ability to non-destructively image microstructures and quantify mineral abundances in three dimensions (3D). The Tanco pegmatite in Manitoba, Canada, has a high abundance of the lithium-bearing mineral spodumene. In this study, all spodumene-quartz intergrowths were collected from zones 45 or 50 of the Tanco pegmatite. Three textural groups of spodumene and quartz intergrowths (SQUI) were recognized: the most abundant type of spodumene-quartz intergrowths observed at Tanco are elongated and oriented crystals, hereafter referred to as (1) “classic SQUI,” less common are quartz-spodumene intergrowths <1 mm referred to here as (2) micro-SQUI and intergrowths of stubby crystals of spodumene and quartz that are more than 1 cm, termed (3) macro-SQUI. The relative 3D relationships between spodumene and quartz in the different SQUI groups were spatially correlated and quantified by micro-CT. The micro-SQUI group showed a mesh of multiple, complexly intergrown spodumene and quartz symplectites. The classic SQUI type showed a unidirectional crystallization texture in the samples, whereas the macro-SQUI group did not show a preference for crystallographic orientation. The relative proportions of the minerals comprising SQUI within small drill core sample volumes were quantified in three dimensions and contrasted to low spatial resolution bulk assay methods such as Rietveld X-ray diffraction (XRD) and bulk ICP-MS. The quantified results from micro-CT were categorized as spodumene and a “less dense than spodumene” fraction that included mostly quartz with minor amounts of muscovite, analcime, and albite. The absolute percentage differences between the micro-CT quantifications of spodumene from 6 out of 8 samples were within ±7% of Rietveld XRD results and 7 out of 9 samples were within ±10% of the calculations based upon the whole-rock geochemistry. Although not all intergrowths of spodumene and quartz are interpreted to have originated by replacement of petalite, there are many instances where this texture resulted from the breakdown of petalite; this texture has been termed “SQUI.” This should result in intergrowths containing a weight percent ratio of 60% spodumene to 40% quartz. Our micro-CT results show spodumene modal abundances between 54 to 70 wt%, suggesting that SQUI can have multiple origins and that the currently accepted assumption is too simplistic. Our research shows that micro-CT can successfully be used as a 3D visualization and quantification tool of Li-silicate minerals while providing additional contextual information that low spatial resolution bulk techniques cannot provide. This study also shows the diverse possibilities of utilizing micro-CT analysis in visualizing silicate textural information between minerals with density differences of at least 0.55 g/cm 3 , which includes investigating spodumene and quartz in 3D, highlighting an impactful use of micro-CT as a critical mineral visualization and quantification tool in pegmatites. This is important as the texture of spodumene can assist in determining the origins of lithium mineralization and can influence metallurgical processes. Understanding these aspects is vital for identifying further mineralization within deposits and assessing their economic viability.

Planetary surface missions have greatly benefitted from intelligent systems capable of semi-autonomous navigation and surveying. However, instruments onboard these missions are not similarly equipped with automated science analysis classifiers onboard rovers, which can further improve scientific yield and autonomy. Here, we present both single- and multi-mineral autonomous classifiers integrated using the results from a co-registered dual-band Raman spectrometer. This instrument consecutively irradiates the same spot size on the same sample using two excitation lasers of different wavelengths (532 and 785 nm). We identify the presence of mineral groups: pyroxene, olivine, potassium feldspar, quartz, mica, gypsum, and plagioclase, in 191 rocks. These minerals are among the major rock-forming mineral groups, so their presence or absence within a sample is key for understanding rock composition and the environment in which it formed. We present machine learning methods used to train classifiers and leverage the multiple modalities of the dual-band Raman spectrometer. When testing on a novel sample set for single-mineral classification, we show accuracy scores up to 100% (varying by mineral), with a total classification rate (all minerals) of 91%. When testing on a novel set of samples for multi-mineral classification, we show accuracy scores up to 96%, with a total classification rate of 73%. We end with several hypothesis tests demonstrating that dual-band Raman spectroscopy is more robust and improves the scientific yield for mineral classification over single-band spectroscopy, especially when combined with our multimodal neural network.

Long-term storage of CO 2 in nesquehonite (MgCO 3 ·3H 2 O) relies on its transformation to highly stable magnesite (MgCO 3 ) in a naturally occurring, centuries-long process. Here, we pair in situ X-ray diffraction (XRD) and thermogravimetric analysis to investigate the thermal transformation (30–650 °C, 5 °C/min) of nesquehonite to magnesite, under both open and closed experimental conditions in a supplied atmosphere of CO 2 or N 2 , and the presence or absence of self-generated gases (i.e., CO 2 , water vapor). We found that following the structural collapse of nesquehonite, magnesite only forms in the presence of gaseous CO 2 , whether that be externally supplied or self-generated. This is consistent with a dehydration-crystallization mechanism, with increased local accumulation of CO 2 (and in a closed system, H 2 O vapor) shifting thermal events to higher temperatures, allowing for the crystallization of magnesite. Approximately 20 wt% more magnesite formed when nesquehonite was flushed with CO 2 gas during heating in an open system, rather than held within a closed, static CO 2 atmosphere. We hypothesize that this difference is due to complete dehydration being more difficult to achieve in a closed system, delaying the crystallization of magnesite. Additionally, the distribution of passivating reaction products on unreacted mineral cores may occur in closed systems, where self-generated humidity is retained and the dissolution-precipitation of reaction products may occur at mineral surfaces. We also found that amorphousmaterials are dominant intermediate stores for CO 2 , which is significant given they are not typically considered during carbon accounting in natural landscapes or engineered settings. We proposed a novel method to accurately quantify amorphous solids from XRD data during in situ studies where significant gas loss occurs. Our findings further our mechanistic understanding of how magnesite forms from crystalline and amorphous precursors under a range of environmental and industrial conditions, which is key to optimizing stable CO 2 storage in Mg-carbonate minerals. In particular, it highlights the importance of considering the role of amorphous phases, atmospheric composition, and self-generated gas retention during magnesite formation.

The formation of bonanza Au-Ag-telluride ores in adularia-sericite epithermal deposits is hypothesized to be attributed to the input of magmatic fluid into flow systems dominated by barren meteoric water. However, understanding of the role and importance of magmatic fluids in the formation of bonanza ores remains limited. To address these concerns, we conducted Cu isotope analyses of chalcopyrite, which coexists with Au-Ag-tellurides in the Te-rich Sandaowanzi deposit located in northeastern China, as well as ore-bearing quartz veins, coeval igneous rocks, and older igneous rocks that underlie the deposit. To aid interpretation, we use geochemical modeling techniques along with O isotope data from calcite and quartz, as well as thermal outputs from modern geothermal systems. At Sandaowanzi, the δ 65 Cu values of chalcopyrite vary widely, ranging from 0.48 to 0.86‰. These values are higher than underlying Early Jurassic monzogranite (−0.06 to 0.27‰), as well as coeval Early Cretaceous andesite and basaltic andesite (0.01 to 0.11‰) and Early Cretaceous dacite and granodiorite (0.33 to 0.52‰). The O values of calcite vary from −3.2 to 6.7‰. The present isotope data, together with previous δ 18 O analyses of quartz, support the idea that the fluids responsible for ore formation at Sandaowanzi were derived from a magmatic source. Progressive input of magmatic fluids into convecting meteoric water explains the telluride precipitation. Subsequent boiling can explain Au, Ag, and Cu precipitation in the upwelling limb of convection cells. Injection of high-temperature magmatic fluids (∼300 °C) into shallow meteoric groundwater (∼250 °C) and formation of Au-Ag-telluride ores can take place over a relatively short timeframe, typically around 1000 years. In contrast, the process of electrum precipitation occurs at a later stage compared to the formation of Au-Ag-telluride ores in the boiling zones (<300 °C). These findings indicate that Au-Ag-telluride precipitation occurs at the mixing interface under high temperatures (>300 °C), suggesting that it is located at greater depths compared to typical Au-Ag mineralization in adularia-sericite epithermal systems.

Nanomineral opal-CT is a natural precursor to quartz formed by various geological processes, including weathering, biological precipitation, hydrothermal alteration, and shock metamorphism. These processes play a crucial role in the formation of siliceous rocks as well as abiotic and biogenic interactions in natural systems. Hydrous opal-CT was recently found on the surfaces of Mars and the Moon by microanalyses and remote sensing, which has led to further investigation into the characteristics of opal-CT. In this work, we have investigated the local structures of natural opal-CT samples with various degrees of crystallinity using a combination of synchrotron X-ray diffraction (XRD), X-ray scattering structure factor S ( Q ) analysis, transmission electron microscopy (TEM), and pair distribution function (PDF) analysis. The combined results indicate that opal-CT is mainly composed of interstratified tridymite and cristobalite nanodomains with twins and stacking faults. S ( Q ) patterns are used to delineate the XRD data of opal-CT samples, which provide more precise peak profiles, allowing for better determination of the degree of ordering. TEM images and selected-area electron diffraction (SAED) patterns directly show nanodomain structures with planar defects. X-ray PDF analysis is a powerful characterization tool that can further unveil local structures, defects, and crystallinity in opal-CT. The rise in ordered domain size and two peaks at 10.01 and 11.16 Å in G( r ) plot reflect the increase in the amount of cristobalite units and crystallinity. Both four- and eight-membered [SiO 4 ] rings are created by twinning and stacking faults of the tridymite and cristobalite domains. X-ray PDF analysis provides unique insights into the local structures, crystalline sizes, and ordering degree of opal-CT. Quantifying the crystallinity of natural opals is important to understanding the diagenetic processes of opals and the associated diatomaceous clays in sedimentary formations.

Crystallographically oriented lamellar to acicular rutile ± ilmenite inclusions in garnet may record important information about the pressure ( P ), temperature ( T ), and petrotectonic evolution of the lithosphere. However, reading this record requires a robust understanding of titanium (Ti) substitution mechanisms and solubility in garnet. To this end, we examine the Ti substitution systematics revealed by 87 garnet analyses from previously published experimental studies relevant for granulites, high-pressure granulites, and deep crustal magmatic rocks. The experimental P - T conditions range mostly between 850–1230 °C and 1.0–2.7 GPa; four 3.2 GPa, 1075–1150 °C ultrahigh- P , ultrahigh- T examples are also included. We find that normalizing garnet formulas based on two octahedral sites per 12 O atoms provides better Fe 3+ estimates than the standard 8-total-cation scheme. The Fe 3+ must be constrained as both it and Ti substitute on octahedral sites. Graphical analysis reveals that the main substitutions are Tschermak-Ti ( VI Ti 4+ + IV Al 3+ ↔ VI Al 3+ + IV Si 4+ ) and andradite ( VI Al 3+ ↔ VI Fe 3+ ), with lesser but nonetheless important contributions by andradite-Ti ( VITi4+ + IV Al 3+ ↔ VI Fe 3+ + IV Si 4+ ) and alkali-Ti ( VI Ti 4+ + VIII (Na + ,K + )↔ VI Al 3+ + VIII M 2+ ). Here, VIII M 2+ denotes dodecahedrally coordinated divalent cations (Ca, Fe 2+ , Mg, Mn). We also posit a small role for Ti substitution coupled to dodecahedral vacancies. These inferences were independently tested using a Monte Carlo modeling procedure developed herein that quantitatively reproduces both the nature and extent of the observed substitutions. We also compared the experimental data with a representative suite of natural garnet analyses. In general, the natural garnets have far lower Ti and alkali (Na ± K) contents than the experimental ones. We attribute this to Ti and alkali loss in nature during exhumation and cooling by processes including diffusion and interface-coupled dissolution-reprecipitation. Some fraction of the lost Ti can be hosted by exsolved precipitates of crystallographically oriented rutile ± ilmenite. However, in many cases, these are absent, and the Ti must have left the garnet structure entirely. The lost alkalis may be hosted by exsolved amphibole or mica precipitates, but these are relatively uncommon, suggesting that alkalis are typically transferred from garnet to the matrix or to non-precipitate inclusions.

Smectite, a major barrier material for contaminants in Earth’s critical zone, is a layered aluminosilicate mineral with cis -vacant ( cv ) and trans -vacant ( tv ) configurations. High-temperature transformations of smectite are directly related to smectite’s thermal reactions. However, the precise thermal reaction mechanisms and thermally induced structural transitions of cv and tv smectite remain debated. In this study, we systematically investigated the mechanism of thermal reactions of cv and tv smectite models using reactive force field (ReaxFF) molecular dynamics. We explored the deprotonation and the intralayer dehydration steps of cv and tv smectites at 700 and 900 K. The results revealed that the dehydroxylation reaction of cv smectite exhibited more difficulty than tv smectite at 700 K, while demonstrating less difficulty at 900 K. Furthermore, it was found that the dehydroxylated cv and tv smectites evolved to a consistent structure spontaneously. Our findings further confirmed that cv smectite has a higher dehydroxylation temperature than tv smectite and thus provided a theoretical basis for distinguishing cv and tv smectites using thermogravimetric analysis (TGA). Moreover, we gathered TGA data of smectites from different regions, confirming that montmorillonites have a cv structure and almost all smectites from China (over 11 provinces) are cv . This study provides a molecular-level understanding of the thermal reaction mechanisms of smectites and a physical basis for further study and application of smectites.

Iron can exist in serpentinite in various oxidation states. Changes in the oxidation state of Fe play a crucial role in geological processes, including supporting diverse biological systems on the ocean floor and the redox states of aqueous fluids released in subduction zones. Synchrotron X-ray absorption nearedge structure (XANES) spectroscopy has been used to measure the oxidation state of Fe in serpentine minerals; however, a general scheme for estimating the oxidation state of Fe in serpentinite composed of several Fe-bearing minerals has not been established. We evaluated the accuracy of using XANES spectra to estimate the Fe 3+ /ΣFe ratio (molar ratio of Fe 3+ to total Fe) of physical olivine-magnetite mixtures and serpentinites. Two approaches were tested: (1) linear combination fitting (LCF) and (2) pre-edge peak analysis of XANES spectra. Estimating Fe 3+ /ΣFe using analysis of the pre-edge peaks was not always suitable when magnetite was included. Using LCF, XANES spectra are well fitted by the optimal combination of Fe-bearing minerals, even for mixtures of magnetite and Fe-bearing silicate minerals (i.e., serpentine and olivine). The Fe 3+ /ΣFe ratios of the serpentinites were estimated with a root mean squared error (RMSE) of 0.14 with LCF. These results demonstrate that LCF of XANES spectra is useful for estimating the oxidation state of Fe in serpentinites.

Prolonged and episodic magmatic-hydrothermal processes have been proposed to be important in forming large-tonnage Cu volcanogenic massive sulfide (VMS) deposits but are difficult to document and remain poorly understood in ancient VMS systems. In this study, we combine textural evidence and in situ analysis of sulfur isotopic composition with trace elements of pyrite from the well-preserved, large-tonnage Ashele VMS deposit (Central Asian Orogenic Belt, NW China) to elucidate the origin of the ore-forming materials and controlling factors of VMS deposits. The distribution of hydrothermal alteration and mineralization allows the Ashele deposit to be divided into five zones: massive sulfide, quartz-pyrite, chlorite-chalcopyrite-quartz-pyrite, quartz-chlorite-sericite-pyrite, and quartz-sericite-pyrite zones. Cu mineralization is mainly hosed in the massive sulfide and chlorite-chalcopyrite-quartz-pyrite zones. Three texturally and compositionally distinct types of pyrite from the Cu mineralization zones have been recognized. The first type of growth zones with high Cu, As, and volatile elements (e.g., Hg and Tl) concentrations and negative δ 34 S values (−7.83‰to −0.35‰) are observed in pyrite grains from the massive sulfide zone most likely formed from the input of magmatic volatiles degassed from the underlying magmatic systems. The second type of Cu-As-rich growth zones in pyrite grains from the chloritechalcopyrite-pyrite zone is not enriched in volatile elements and has positive δ 34 S values (2.59–6.56‰), which are interpreted to have precipitated during fluid boiling. The third type of growth zone, without Cu-As enrichment but having positive δ 34 S values (0.30–9.76‰) in pyrite grains from both mineralization zones, was probably formed without boiling or magmatic volatile input. Our results suggest that multi-stage magmatic degassing or fluid boiling accompanied by Cu precipitation recorded in individual pyrite grains can reveal episodic magmatic-hydrothermal activity, which is an essential factor in forming large-tonnage VMS deposits.

Igneous microtextures are significant tracers of magmatic processes as these provide important information about magma evolution. Oxy-symplectite intergrowth of orthopyroxene (host) with Fe-Ti oxide (lamellae) is described from the Atlantis Bank, an Oceanic Core Complex (OCC) along the ultraslow spreading Southwest Indian Ridge (SWIR). This texture is widespread in the oxide-rich lithologies recovered from the lower crustal section of the Atlantis Bank. There exists a long-standing debate on the magmatic vs. metamorphic origin of the oxy-symplectites. The symplectitic intergrowth is usually noted wherever the olivine grain is in intimate proximity to the magmatic magnetite and is developed at the expense of the olivine. Comparative oxybarometric results between the ilmenite-magnetite pairs close to the symplectites and those away from the symplectites reveal relatively higher fO2 $f_{\mathrm{O}_2}$range for the former group. These observations along with phase equilibria modeling suggest that oxidation of olivine primo-crysts may lead to the development of oxy-symplectite in the studied gabbros (sensu lato). Furthermore, the compositional variabilities between the symplectitic phases and the discrete magmatic phases away from the symplectite indicate that the origin of the oxy-symplectite took place under subsolidus conditions. Additionally, phase equilibria modeling reveals that for the observed range of olivine compositions, higher oxidizing conditions are required for symplectite formation at higher temperatures. Synthesizing all the results, we suggest that the formation of the oxy-symplectite in this lower crustal section is a subsolidus process, where the oxide phases (especially magnetite) aided the oxidation of olivine.

Al-hematite occurs in a wide range of terrestrial soils, but the impact of hydrologic factors on the formation and preservation of Al-hematite remains uncertain. Experimental studies indicate that the ratio of the intensity (I) of the (110) reflection to the intensity of the (104) reflection [(I(110)/I(104)] increases with increasing Al content in a series of synthetic Al-hematite analyzed by X-ray diffraction (XRD), whereas the ratio of the full-width at half maximum (W) of the (110) reflection to the full-width at half maximum of the (104) reflection [W(110)/W(104)] decreases. Quantitative constraints were applied to determine the various levels of Al-substituted hematite in a basaltic laterite (a 48-m-long drill hole) from Hainan Island in South China. The spatial correlation between the distribution of hematite with varying Al content and the location of the groundwater table in the basaltic laterite indicates that hydrologic conditions play a crucial role in regulating the formation and preservation of Al-hematite. The weathering of basalt in a stable water-saturated environment with a relatively slower flow rate promotes the formation of Al-poor hematite. Conversely, the formation of Al-rich hematite was favored by a relatively high flow rate and alternating wet and dry conditions above the groundwater table. Additionally, capillary water in the surficial soil facilitates the expulsion of Al during the recrystallization of Al-rich hematite, resulting in the formation of Al-poor hematite in the surficial soil. Observations from landed instruments and ground-based telescopes have led to the longstanding suspicion that Al-hematite exists on the surface of Mars. The potential presence of Al-hematite in certain martian outcrops may suggest the existence of transient liquid water with slightly higher flow rates, such as episodic floods, emphasizing the dynamic hydrologic conditions on Mars. Moreover, this study suggests that visible and near-infrared (VNIR) spectroscopy can be employed to identify and characterize Al-rich hematite. This approach could be employed to assess the potential presence of Al-rich hematite on Mars, aiding in the study of the planet’s hydrologic environment.

Allanite-(Sm), the third samarium mineral to be discovered, was studied using electron microprobe analysis and single-crystal X-ray diffraction. It is isostructural withmonoclinic epidote-supergroup minerals and belongs to the allanite group. The mineral was found in a granitic pegmatite in a serpentine quarry near Jordanów Śląski in Lower Silesia, SW Poland. It occurs as subhedral to anhedral crystals with sizes of up to ∼150 μm accompanied by allanite-(Nd), allanite-(Y), clinozoisite, hingganite-(Y), and xenotime-(Y). Allanite-(Sm) is yellowish-brown and shows a white streak, a vitreous luster, and a Mohs hardness of ∼6. It is brittle, with conchoidal fracture and imperfect cleavage. The calculated density is 3.842 g·cm −3 , and the calculated mean refractive index is close to 1.737. The holotype crystal contains (in wt %) 33.08(11) SiO 2 , 0.08(3) TiO 2 , 21.15(9) Al 2 O 3 , 0.45(6) Sc 2 O 3 , 0.48 FeO 3(calc) , 0.02 2 (1) V 2 O 3 , 2.49(31) Y 2 O 3 , 0.18(4) La 2 O 3 , 0.95(9) Ce 2 O 3 , 0.34(6) Pr 2 O 3 , 3.52(31) Nd 2 O 3 , 6.12(23) Sm 2 O 3 , 0.06(2) EuO, 3.25(21) Gd 2 O 3 , 0.34(2) Tb 2 O 3 , 0.94(7) Dy 2 O 3 , 0.15(4) Ho 2 O 3 , 0.16(3) Er 2 O 3 , 0.07m(6) T 2 O 3 , 0.06(4) Yb 2 O 3 , 0.28(4) MnO, 8.38 FeO (calc) , 0.13(2) MgO, 13.71(15) CaO, and 1.95 H 2 O ()+ calc ; the total is 98.04. The empirical EPMA+SREF formula is Al (Ca 0.966 Mn 0.022 Fe0.0102+ $\mathrm{Fe}_{0.010}^{2+}$) Σ0.998 A2 (Ca 0.372 Sm 0.192 Y 0.121 Nd 0.114 Gd 0.098 Ce 0.032 Dy 0.028 Pr 0.011 Tb 0.010 La 0.006 Er 0.005 Ho 0.004 Eu 0.002 Tm 0.002 Yb 0.002 )Σ 0.998 M1 Al 0.998 M2 Al 0.998 M3 Fe0.6282+Al0.275Sc0.036Fe0.0333+Mg0.018Ti0.005 V0.0023+Σ0.998 $\left(\mathrm{Fe}_{0.628}^{2+} \mathrm{Al}_{0.275} \mathrm{Sc}_{0.036} \mathrm{Fe}_{0.033}^{3+} \mathrm{Mg}_{0.018} \mathrm{Ti}_{0.005} \mathrm{~V}_{0.002}^{3+}\right)_{\Sigma 0.998}$( T1–T3 Si 3.012 O 11 )O(OH), the simplified formula is Ca(Sm,REE,Ca)Al 2 (Fe 2+ ,Al,Fe 3+ )(Si 2 O 7 )(SiO 4 )O(OH), and the ideal formula is CaSm(Al 2 Fe 2+ )(Si 2 O 7 )(SiO 4 )O(OH), which requires (in wt%) SiO 2 30.37, Al 2 O 3 17.18, Sm 2 O 3 29.38, FeO 12.11, CaO 9.45, and H 2 O 1.52; the total is 100. Allanite-(Sm) is monoclinic, space group P 21/ m , with the following unit-cell parameters: a = 8.8923(6) Å, b = 5.7005(3) Å, c = 10.1280(8) Å, β = 115.445(9)°, V = 463.59(6) Å 3 , Z = 2, and a:b:c = 1.5599:1:1.7767. The T site is exclusively occupied by Si, the A1 site is occupied by Ca and Mn, and the A2 site is mainly occupied by rare earth elements (REE), of which Sm is dominant. The M1 and M2 sites are occupied by Al and the M3 site by divalent cations, of which Fe 2+ , characteristic of allanite-type species, is dominant. Allanite-(Sm) and the associated allanite-(Y), allanite-(Nd), and hingganite-(Y) are secondary minerals precipitated from Ca-rich hydrothermal fluid during the metasomatic alteration of the Jordanów Śląski pegmatite. They accumulated REE released by the alteration of nearby xenotime-(Y). The disequilibrium rapid crystallization of REE-selective allanite and hingganite phases in an environment strongly enriched in heavy REE (HREE) relative to light REE (LREE), as well as small-scale heterogeneities in REE abundances in the fluid, resulted in the formation of exotic allanite species, including allanite-(Sm).

Campi Flegrei (CF) is a large volcanic complex west of Naples, in a densely populated region at high volcanic risk due to recurrent ground uplift and subsidence (bradyseism) that has been ongoing since at least Greco-Roman times. We compare the current period of unrest beginning in 2005 with that of the bradyseism crisis of 1982–84. Despite the similarity in the quasi-radially symmetric pattern of ground deformation suggesting a similar source location and overpressure, the current uplift rate is about 8 times lower, and the seismic release energy is an order of magnitude lower than in 1982–1984 and mainly located in isolated regions below the Solfatara-Pisciarelli area. We interpret the recent earthquake swarms at Solfatara-Pisciarelli as a reflection of the activation of a fault system that was inactive during previous bradyseism crises. Furthermore, the increase of Solfatara-Pisciarelli fumarole mass flux is the manifestation of fluid discharge that significantly reduces the uplift rate of the ongoing bradyseism event. As a result, the effects of bradyseism in the CF system have self-attenuated through increased fluid expulsion (“breathing or exhalation”) from the deep, lithostatically pressured reservoir. Having gained a clear understanding of the causes of bradyseism at CF, we suggest that modern geoengineering approaches developed to exploit high-temperature geothermal reservoirs may be employed to manage fluid flow and reduce the pressure exerted by geothermal fluids in the Solfatara-Pisciarelli area with the aim of minimizing the risk of phreatic eruptions and, concomitantly, reducing uplift and seismicity. This approach requires concerted and cooperative efforts between geoscientists, engineers, government officials, and the general public.

This issue of New Mineral Names provides a summary of the newly described minerals from 2024 and selected information for recent descriptions from September 2024 to January 2025. New mineral name trends and observations are presented with an objective examination of new species and their broader implications. All minerals presented have been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC).