Argentotennantite-(Fe), Ag6(Cu4Fe2)As4S13, has been approved as a new mineral species (IMA 2023-126) by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (CNMNC-IMA) using a sample of quartz gangue with argentotetrahedrite-(Zn), pyrargyrite, baryte, and siderite from the San Genaro mine, Castrovirreyna Province, Huancavelica, Peru. Argentotennantite-(Fe) occurs as anhedral grains up to 100 µmλRΣMe = 16 atoms per formula unit, is (Ag3.36Cu2.70)Σ6.06(Cu4.05Fe1.88Zn0.07)Σ6.00(As2.29Sb1.66)Σ3.95S12.82. Argentotennantite-(Fe) is cubic,
Black opal, a variety of opal pigmented by organic matter, from Volyn, western Ukrainian Shield, was investigated by means of scanning electron microscopy (SEM), electron microprobe analyses (EMPAs), μ-X-ray fluorescence (μXRF) element mapping, X-ray diffraction (XRD), and Fourier transformed infrared (FTIR) spectroscopy, and was dated by U-Pb by laser ablation (LA-ICP-SF-MS). Opal occurs as several centimeter large blocks and as cement in a breccia within pegmatites, which intruded into granites of the ca. 1.7–1.8 Ga old Korosten pluton. Opal samples were collected underground in miarolitic cavities of the pegmatites, which also host kerite, fossilized organic material (called Volyn biota). Inclusions in opal are typical pegmatitic minerals such as alkali-feldspar, Li-mica, and quartz. Buddingtonite and ammonium-bearing muscovite, as well as shape relicts of the fossils in opal, indicate interactions of organic material with the pegmatite.The XRD data indicate opal-CT with a complex pattern of the ∼ 4 Å peak. Its microstructure, as seen in SEM and back-scattered electron maps, consists of nanograins 15–35 nm in size, arranged in sphere-like structures, in some samples ∼ 5 µm-large and monodisperse, in others polydisperse with diameters of between 1 and 10 µm, and as lepispheres. Organic matter plus water makes up ∼ 10 wt %–15 wt %. The organic matter is situated within the core, in concentric zones in the sphere-like structures and in the matrix around them. Infrared (IR) spectra confirm the presence of silanol SiOH and CHn. At the contact with pegmatitic material, a pyrite-enriched zone was observed and interpreted as resulting from the infiltration of a late Fe- and Mn-bearing fluid along grain boundaries.Results of U-Pb dating yield a minimum age for opal formation of ∼ 200 Ma, and provide evidence for fluid overprint during the Jurassic (170–155 Ma) and Quaternary. These ages are much older than reported so far in opal from deposits worldwide. Furthermore, the here-reported occurrence of opal in pegmatitic rocks is unique, as all other opal deposits are either sedimentary or volcanic hosted.
Mineralogical, paragenetic, and geochemical data on sulfidic mineralization from the Cínovec Li–Sn–W greisen-type deposit (Bohemian Massif, Czech Republic) were used to refine the evolution of mineralization at this world-class deposit and to clarify the relationship between base-metal sulfides and the Li–Sn–W mineralization. Sulfides occur in three main settings: (i) quartz–zinnwaldite veins, (ii) massive greisens and greisenized granites, and (iii) late baryte–fluorite veins that locally overprint earlier types. Electron microprobe analyses and detailed BSE imaging reveal multiple mineralization stages and a surprisingly large suite of sulfide minerals. They were divided into several mineralization stages, including the greisen stage (molybdenite, arsenopyrite, safflorite), early sulfide stage (stannite–kësterite, stannoidite, sphalerite), intermediate sulfide stage (galena), and late sulfide stage (pyrite, marcasite, chalcopyrite, tennantite–tetrahedrite, enargite, lautite, Cu–Ag–Bi–Pb sulfosalts, native Bi, Cu sulfides, pearceite, cupropearceite, stromeyerite). A minor amount of sulfides was remobilized during later the fluorite–baryte stage. Distribution of sulfide mineralization at the deposit is irregular; sulfides are not strictly bound to prevalent Li–Sn–W mineralization. The dominant sphalerite-bearing assemblages (Zn–Pb–Cu) display average grades of ∼ 100–200 ppm Zn (however, Zn is partly contained in zinnwaldite), 20–50 ppm Pb, and < 50 ppm Cu in disseminated mineralization, with locally elevated In contents (≤ 0.53 wt %) in sphalerite. Progressive evolution of metal contents in the reduced sulfide-bearing hydrothermal fluid proceeds from Zn–Cu–Sn to Pb–Bi–Ag and As–Sb. Late-stage sulfate- and fluorine-bearing fluids partly altered earlier mineralization but did not deposit significant ore content.
The study of two outcrops of schists in the Padul Fault area has allowed us to corroborate the enrichment in clay minerals in the fault zone. In the case of the dark schist outcrop, the fault rocks show a reduction in mineral diversity with aluminosilicates, characteristics of the regional metamorphism losing and showing an enrichment in quartz and kaolin-group minerals. In the calc-schists, there is a clear presence of chlorite in the fault rocks, which is practically absent in the fresh rocks, as well as R1 illite/smectite and smectite. The geochemical characterization also showed differences between fresh and fault rocks, more evident in the dark schists than in the calc-schists, with an increase in SiO22O3, Fe2O3, and MgO in the fault rocks with respect to the protolith. The presence of authigenic chlorite in the fault rocks from the calc-schists allowed for the application of semi-empirical thermometric methods for the fault rocks giving predominant temperatures < 225 °C. All these data are consistent with the circulation of low-temperature fluids along the fault zone that interact with the rocks, promoting clay mineral formation. Such was also the findings in a previous study focused on the predominant rocks of the Padul Fault area, which are dolostones, affected by the dynamics of this fault. Interestingly, the circulation of fluids promoted by the existence of the Padul Fault has not been restricted to the fault rocks, given that some of these clay minerals (kaolinite and smectite) are also present in the fluid-accessible zones of the metamorphic protolith. These data highlight the importance of faults in the retrograde mineralization processes of metamorphic rocks.
This study evaluates Tibet leucogranites as a potential raw material for high-purity quartz. We systematically investigate the petrography, geochemistry, and purification potential of leucogranites from the Ama Drime Massif of the Dinggye area. Our results demonstrate that these leucogranites hold considerable potential to produce high-purity quartz with SiO22
Erzwiesite, ideally Ag8Pb12Bi16S40, ZThe empirical formula is (Ag,Cu)8.23(Pb,Cd)11.33(Bi,Sb)16.31 (S,Te,Se)40.03Erzwiesite crystallises in space group Cmcma4.085(5), bc = 33.92(4) Å, and V1866(4) ų). Erzwiesite is the first natural (8:8) homologue of the lillianite homologous series and is named after its type locality.
Erzwiesite, ideally Ag8Pb12Bi16S40, Z= 1, is a new sulfosalt mineral discovered in the Erzwies mining area, Gastein Valley, Salzburg Province, Austria. The mineral occurs as small black, irregular needle-like crystals mixed with galena and heyrovskýite in a quartz matrix. In reflected light, erzwiesite is greyish white. Under crossed polars it is distinctly anisotropic, and the rotation tints change from pale brown to pale bluish grey to dark brown. Reflectance measurements in air yield the following
Plumbogottlobite (IMA 2025-075), PbMg(VO4)(OH), is a new mineral from the Glücksstern mine, Gottlob Hill, Friedrichroda, Gotha District, Thuringia, Germany; it is a late-stage, low-temperature hydrothermal mineral occurring on baryte and hausmannite. Plumbogottlobite forms orange-brown tablets up to about 0.2 mm in diameter. The mineral has a light-orange-brown streak, adamantine lustre, a Mohs hardness of ∼ 4 to 4.5, brittle tenacity, irregular to conchoidal fracture, no cleavage, and a calculated density of 5.359 g cm−3. Optically, plumbogottlobite crystals are biaxial (–), with 2V=84(1)°. The empirical formula from electron probe microanalyses based on 5 O apfu0.89□0.11)Σ1.00(Mg0.77Cu
Lopatkaite, ideally Pb10As2Sb6S22Z=4), is a new arsenic-bearing sulfosalt found in the Madoc deposit, Taylor Pit, Ontario, Canada. Associated minerals in the holotype specimen are boulangerite, veenite, and sterryite, all embedded in a calcite matrix. Lopatkaite is greyish black and opaque, with metallic lustre and dark-grey streak. It is brittle without any discernible cleavage and parting and has a Mohs hardness of 3–3.5. In reflected light lopatkaite is greyish white, with distinct bireflectance and pleochroism from white to grey, especially in oil. Under crossed polarisers, anisotropism is distinct, with rotation tints in shades of grey. Reflectance measurements in air yield the following
Calcite has been shown to incorporate trivalent actinides into its crystal lattice, highlighting its potential to contribute to radionuclide retention processes in the environment. Earlier studies on calcite's elemental uptake were conducted under controlled laboratory conditions, which do not fully capture the complexities of natural environments. To gain a deeper understanding of calcite's uptake capacity under natural conditions, a sample from the Wenzel ore mine, Germany, was analyzed, originating from a calcite vein that formed under conditions relevant to deep geological-waste repositories. The chemical analogy between rare earth elements (REEs) and trivalent actinides helps to evaluate the retention potential and incorporation mechanisms of trivalent radionuclides. A micro-X-ray fluorescence (µXRF) element map revealed that the investigated calcite consists of an euhedral crystal core exhibiting sector zoning, characterized by trace element heterogeneity across coevally grown crystal faces. High-resolution laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) further refined and quantified the elemental distribution, revealing preferential incorporation of specific elements, particularly REEs, within one sector of the calcite. Remarkably, this sector showed REE concentrations over 200 times higher than those in the depleted sector, indicating a significant potential for the retention of trivalent actinides. Furthermore, the data indicate that charge equilibration of incorporated trivalent cations occurs via two processes: coupled substitution with monovalent cations and vacancies in the crystal structure. Overall, these results demonstrate that sector-zoned calcite formed under repository-relevant conditions can maintain high retention potential for trivalent actinides, even in environments depleted in monovalent cations.
The Atlantis Bank at the Southwest Indian Ridge (SWIR) is probably the most thoroughly investigated oceanic core complex from a typical slow-spreading ridge. Here, ODP (Ocean Drilling Program) conducted two drilling expeditions at Drill Site 735B. The gabbro massif is characterized by the presence of hundreds of felsic veins, which are rocks consisting of evolved, silica-rich material showing the composition of typical “oceanic plagiogranites”. Two models have been suggested for their generation: (1) the extreme differentiation of a MORB magma, resulting in a highly differentiated melt, and (2) the hydrous remelting of gabbroic rocks in the deep oceanic crust.Detailed petrographical and microanalytical investigations of gabbroic rocks from ODP drill core 735B reveal that many of these gabbros exhibit microstructures characteristic of hydrous partial melting of gabbro. Key features that led to this conclusion are zones of anorthite-enriched plagioclase on grain boundaries, which form parageneses with interstitial brown amphibole and orthopyroxene. These are interpreted as the residual phase assemblage left after hydrous partial melting. These events are triggered by water-rich fluids migrating along grain boundaries within the cooling gabbro complex at temperatures above the wet gabbro solidus. This conclusion is supported by two further observations: (1) trace element concentrations in the An-enriched plagioclase (Ti, Mg, and K) are strongly impoverished, in line with experiments simulating the hydrous partial melting of gabbro. (2) The bulk TiO22-impoverished cumulate gabbro. This contrasts with melt compositions derived through fractional crystallization of MORB, where TiO2
Friisite, ideally Pb8Al3Si8O27Cl3, is a new mineral discovered in a museum sample from the Långban mine in Värmland, Sweden. It occurs as subhedral, flaky grains up to 150 µm in size, forming aggregates within a medium-grained skarn matrix and contiguous to jagoite. Both are associated with melanotekite, aegirine–augite, albite, baryte, fluorapophyllite-K, margarosanite, alamosite, native lead, a serpentine group mineral, and a wickenburgite-like mineral. Friisite is white to colorless with a white streak and sub-adamantine luster. The mineral is transparent and does not fluoresce under UV light. It is brittle, with an uneven fracture and perfect cleavage on {001}. Mohs hardness is 4–5 (by analogy with jagoite). The calculated density is 5.54(1) g cm−3. Optically, friisite is non-pleochroic and uniaxial (–). Point analyses by means of an electron microprobe using wavelength-dispersive spectroscopy resulted in an empirical formula (based on 30 O+Cl):
The new mineral delchiaroite, Cu3I(CH3S)2, has been discovered in La Piana quarry, Colonnata marble basin, Carrara, Apuan Alps, Tuscany, Italy. It occurs as light-yellow acicular crystals, elongated on [010], up to 0.1 mm in length and is brittle, with a light-yellow streak and a greasy luster. In reflected light, delchiaroite is light gray with abundant internal yellow reflections; anisotropism is moderate, with gray tints. Reflectance values for the four COM wavelengths are (λ
In surface soils and sediments, iron monosulfide (FeS) species, including nanocrystalline mackinawite, tend to quickly form in the presence of iron and sulfide in anoxic conditions. As such, FeS species are the main precursors for the formation of other iron sulfides such as Fe3S42K-edges to study the structural and electronic properties. Moreover, in order to strengthen our interpretations, we confirmed the shape and relative energy of pre-edge features in the S K-edge XANES spectra of mackinawite (FeS) and pyrite (FeS2) model compounds via first-principle calculations. Our results show that, after FeS has precipitated from aqueous Fe(II) and
Gem-quality corundum varieties of ruby and sapphire are one of the most valuable and desired gemstones. Due to their rarity, new methods of synthesis and treatment were developed over the last decades, complicating the reliable identification between natural, treated, and synthetic specimens. Among the geochemical methods used for identification, trace element analysis using laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) is widely applied. However, solely relying on LA-ICP-MS trace element analysis for differentiation between natural and synthetic corundum origins, especially when grown by the hydrothermal method, can potentially lead to misidentifications. To further enable geochemical tracing of corundum, this study explores secondary ion mass spectrometry (SIMS) oxygen isotope analysis. High-spatial-resolution SIMS δ18O
Hydrogen diffusion in major hydrous minerals determines the closure temperatures of isotopic exchange used to track fluid–rock interactions. Deuterium–hydrogen (D–H) exchange was experimentally investigated between minerals and deuterated gas (D2) in an ambient-pressure furnace over the temperature range of 400–650 °C (tremolite, vesuvianite) and between minerals and D2O at high pressure (1.5–3 GPa) and temperature (315–500 °C) in a belt press (glaucophane, epidote). D 
Loparite is a natural perovskite (ABO3) with a complex composition, essentially a solid solution between loparite(-Ce) (Na0.5Ce0.5TiO3), lueshite (NaNbO3), and perovskite (CaTiO3), with small amounts of many other elements. The majority of reported loparite crystals are spinel-type interpenetration twins with compositional zoning. Associated with the high variability of compositions, different crystal structures of loparite were described, and the origin of twinning has not been addressed so far.In this work, we studied a loparite twin composed of two symmetrically intergrown cuboctahedra. Microprobe analyses revealed that the cubic and octahedral growth sectors have slightly different compositions. According to atomic-scale analyses, the cubic sectors with a lower Na:LREE ratio have a disordered orthorhombic structure, while the octahedral sectors with a higher Na:LREE ratio show partial ordering of Na and light rare-earth elements along A-type lattice planes in the [001] direction. The degree of ordering was evaluated by quantitative high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Atomic-scale analyses of (111) and {112}Our observations suggest that the loparite twin was established in the nucleation stage of crystallisation, followed by independent crystallisation of both twin domains from the melt. The initial crystal form was cubic; octahedral sectors evolved when the crystal size was still in the nanometre range, as a result of slow crystal growth. Differences in structural ordering between adjacent growth sectors developed during slow cooling due to the compositional variations. Our results imply that compositionally zoned crystals might show different structural ordering within single domains, which should be considered when interpreting bulk diffraction data of compositionally zoned perovskites.
Götzenite and wöhlerite were found as part of a fissure assemblage in the Fohberg phonolite (Kaiserstuhl, SW Germany), in close association with natrolite and clinopyroxene (aegirine–augite). Crystal grains were separated and investigated by single-crystal X-ray diffraction (SXRD), electron probe microanalysis (EPMA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), showing the presence of two intimately intergrown phases, götzenite and wöhlerite. SXRD analyses showed that both minerals are twinned. Götzenite (Na1.50Ca5.18Sr0.13Fe
Two new minerals, zhenruite, ideally (MoO3)2⋅H2O, and tianhuixinite, ideally (MoO3)3⋅H2O, were discovered, respectively, from the Freedom #2 mine in the central part of the Marysvale volcanic field, Utah, USA, and an unnamed short adit on the Summit group of claims near Cookes Peak, Luna County, New Mexico, USA. Zhenruite occurs as acicular or prismatic crystals (up to