In this work, we evaluated the biological and geological contributions to the formation and preservation of the oxidation zones in Ľubietová-Podlipa, Ľubietová-Svätodušná, Poniky-Farbište and Špania Dolina-Piesky. This case study highlights the importance of the biological contribution to weathering processes of ore deposits. It may be extended to other similar sites in order to assess the magnitude of biological input. Using U-Pb dating, secondary minerals from Podlipa were dated to 22 ± 6 and 19 ± 4 Ma (Lower Miocene). At this time, this region experienced deep weathering under a humid and warm climate and tectonic quiescence. The isotopic (O, H) composition of the secondary minerals shows that they formed from Lower Miocene meteoric water under surface temperatures. The δ13CPDB values in malachite (–19 to –17‰) document a biological source of C, from soil CO2. The δ18OVSMOW values of the PO4 groups in the accessory fluorapatite in the host rocks (1.8 ± 1.7‰, 1σ) and pseudomalachite in the oxidation zone (12.1 ± 2.9‰, 1σ) show substantial biological P input into the oxidation zone. A biogenic source of both C and P agrees well with the palaeoclimatic constraints based on the radiometric dating. The oxidation zones at Podlipa, Svätodušná and Farbište are contemporaneous with kaolin crusts in the same area; they were all preserved only where they were covered by young (14–12 Ma) volcanic rocks and exposed recently by erosion. The other oxidation zones in the Tatric and Veporic units, if they existed, were destroyed by the Pliocene uplift of these units. The oxidation zone at Piesky is younger, dated to 2.5 Ma (Early Pleistocene) when the global temperatures in interglacials were similar to the present, decreasing in glacials by ∼4°C. The different climate at this time is manifested by scattered δ13C values, reflecting surface temperature and vegetation fluctuations at this time.

Paramolybdomenite, ideally PbSeO3, the new mineral (IMA2023–025) dimorphous with molybdomenite, was discovered in the weathering zone of the Western paleo-fumarole field at Mountain 1004, Tolbachik volcano, Kamchatka, Russia. It is a supergene mineral associated with chrysocolla, allophane, atacamite, opal, gypsum, anglesite, linarite, brochantite, munakataite, cerussite, wulfenite, vanadinite, mottramite, volborthite, pyromorphite, fluorpyromorphite, fluorphosphohedyphane, phoenicochroite, vauquelinite, murdochite, fluorite, gearksutite and limonite. Paramolybdomenite occurs as tabular to lamellar crystals up to 0.1 × 0.05 × 0.01 mm and their clusters up to 0.15 mm. It is transparent, bright yellow, with adamantine lustre. Dcalc is 6.743 g cm–3. In reflected light, paramolybdomenite is grey; anisotropism is strong, from brownish-yellow to dark brown. The reflectance values [Rmax–Rmin,%(λ, nm)] are: 11.6–13.9(470), 11.2–11.4(546), 10.9–11.1(589), 10.6–10.7(650). Chemical composition (wt.%, electron-microprobe data) is: PbO 67.63, SeO2 26.25, SO3 5.42, total 99.30. The empirical formula calculated based on 2 Pb+Se+S apfu is Pb1.00Se4+0.78S6+0.22O3.22. Paramolybdomenite is monoclinic, P21/c, a 8.997(1), b 8.159(1), c 9.032(1) Å, β 103.33(1)°, V 645.1(1) Å3 and Z = 8. The strongest reflections of the power XRD pattern [d,Å(I)(hkl)] are: 3.897(16)(012), 3.823(17)(210), 3.534(34)($\bar 202$, $\bar 121$), 3.293(100)($\bar 120$), 3.244(63)($\bar 212$), 2.997(35)(022), 2.981(36)(220, $\bar 221$), 2.788(49)($\bar 113$, $\bar 311$, 202), and 2.760(26)(310, $\bar 302$). The crystal structure was solved from single-crystal XRD data, R = 0.112. Paramolybdomenite is a natural analogue of synthetic α-PbSeO3 whilst molybdomenite is an analogue of β-PbSeO3 (monoclinic, P21/m). In the structure of paramolybdomenite the [Pb2+O9] polyhedra are cross-connected via common edges and are connected via common corners with [Se4+O3] groups to form a quasi-framework. Selenium atoms occupy two crystallographically independent sites; the Se1 site is occupied only with Se4+, whereas Se2 has the mixed Se/S population [substitution of (SeO3)2– for (SO4)2–]. It is shown that the so-called ‘molybdomenite-P21/c’ from the El Dragón Mine, Potosí, Bolivia is in fact the second occurrence of paramolybdomenite.

The new mineral pendevilleite-(Y) (IMA 2022-054), ideally Mg2Y3Al(UO2)2(CO3)7(OH)6(H2O)16, was found in the famous Kamoto-East open-cut, Lualaba province, Democratic Republic of Congo and named after Jean-Marie Pendeville (1936–2002), a specialist in collecting minerals of Congo. The new mineral occurs as extremely thin blades (up to ∼0.08–0.10 mm in length and only ∼1 μm thick), often forming lichen-like aggregates and crusts. It is associated with kamotoite-(Y), astrocyanite-(Ce) and shabaite-(Nd), uranophane and sklodowskite. Pendevilleite-(Y) crystals are whitish or greyish-white, locally pale-bluish white. The mineral is brittle; has an irregular fracture and a Mohs hardness of ∼2. Cleavage is perfect on {001}. Electron microprobe analyses provided (on the basis of 2 apfu U with CO32–, H2O derived from the structure and OH– to keep the electroneutrality) formula Mg1.78[(Y1.42Gd0.36Dy0.33Nd0.16Er0.14Sm0.13Eu0.12Tb0.05Ho0.04Yb0.04Ce0.03Tm0.03Pr0.01)Σ2.86 Ca0.11Pb0.01]Σ2.98Al0.88(UO2)2(CO3)7(OH)5.02(H2O)16. Pendevilleite-(Y) is triclinic, P$\overline 1 $, a = 11.9130(3) Å, b = 13.5252(11) Å, c = 16.1531(3) Å, α = 107.052(3)°, β = 92.7765(19)°, γ = 109.676(4)° and V = 2311.5(2) Å3 (Z = 2) at 97 K. The crystal structure (dynamical refinement against 3D ED data; R1 = 0.0948 for 1168 [I > 3σ(I)] reflections) possesses a large heteropolyhedral framework based on both a finite [(UO2)(CO3)3]4– cluster (UTC cluster) and a dimeric [(UO2)2(CO3)4(OH)2]6– unit formed due to olation of uranyl polyhedra. There are three M sites in the structure, occupied by Y3+ and Ln3+, with symmetry-related equivalents forming a polyoxometalate cluster of the general composition [(Y,Ln)6(OH)8(H2O)4(CO3)4]2+. Additionally, there is one Al site in the structure (symmetrically related equivalents forming a dimer of composition [Al2O2(OH)8]6–), and two Mg sites in octahedral coordination MgO2(H2O)4. In the sizeable channels of the framework (running parallel to c), there are at least eight independent partially occupied and disordered O sites of the H2O molecules.

Montanite, named by Frederick August Genth over 150 years ago for the Montana Territory was the world’s first naturally occurring tellurium oxysalt, but was designated ‘Q’ (questionable) by the IMA-CNMNC until our study in 2022. Like many minerals described in the 19th century it had no designated type specimen. Interrogation of institutional archives, contemporaneous publications and specimen labels reveals three distinct early occurrences, two of which are interpreted as co-type localities. In lieu of being able to conclusively identify or access the original type specimens for research, suitable surrogates were defined as neotypes that respected the historical precedence of the initial discoveries enabling montanite to be formally established as a mineral species. Especially for this historically themed edition of Mineralogical Magazine, this paper presents the process and a case-study of the historical research and decision-making required for new minerals, redefinitions or discreditations that are often out-of-scope of the academic journals that publish the resulting scientific research.

Ranunculite is a rare supergene hydrated aluminium uranyl phosphate reliably reported only from the type locality – the Kobokobo pegmatite in the Sud-Kivu province, Democratic Republic of Congo; its structure has remained unknown until now. Based on 3D electron diffraction data, ranunculite is monoclinic, with a C-centred unit cell: a = 11.1812(7) Å, b = 17.9281(5) Å, c = 17.91548(16) Å, β = 98.350(4)°, and V = 3553.2(2) Å3 (Z = 4). The structure (C2/c) was refined kinematically to R1 = 0.4114 for 1697 unique observed reflections. The structure of ranunculite is based upon infinite uranyl-phosphate sheets of novel topology. The two-dimensional representation of the structural unit consists of hexagons (occupied by U6+), pentagons (occupied by U6+), squares (occupied by Al3+) and triangles (occupied by P5+). Those sheets are stacked perpendicular to c; the interplanar distance is ~9.5 Å. They result from the clusters of edge-sharing uranyl hexagonal and pentagonal bipyramids linked by Al-octahedra and PO4 tetrahedra. The decoration of the sheets is unique but somewhat resembles the arrangement (of U-clusters, squares and triangles) observed in bijvoetite and lepersonnite topologies; the ring symbol is 61514232. In the interlayer, there are two Al3+-hosting sites (one [6]- and [5]-coordinated; the pyramidal one is only partially occupied), as well as isolated H2O groups. There is an extensive network of hydrogen bonds; adjacent sheets are either held by hydrogen bonds only or by tetramers of Al-polyhedra when occupied (through shared O19). This arrangement most probably causes a poor crystallinity of ranunculite (which gives rise to stacking faults observed in the powder diffraction data).

The composition of phosgenite (ideal formula Pb2(CO3)Cl2, sp. gr. P4/mbm with a ≈ 8.15 and c ≈ 8.87 Å) from Monteponi Mine, Iglesias, Sardinia, Italy, its crystal structure and its high-T behaviour up to the onset of decomposition were investigated by a series of chemical analytical and diffraction techniques, including single-crystal X-ray (data collected at 293 K) and neutron diffraction (at 293 and 20 K), in situ high-T powder X-ray diffraction (XRD) and thermogravimetric analysis. Concentrations of >65 elements were measured. The empirical mineralogical formula of phosgenite, obtained by the multi-analytical approach used in this study, is almost identical to the ideal one, with only a few elements measured above the detection limit: Σ(Na2O+K2O+CaO+SiO2) = 0.11 wt.%. The concentration of other industrially relevant elements is insignificant. X-ray and neutron refinements, based on data collected at room T, confirm the previously reported general structural model of phosgenite, while providing a full description of the displacement parameters of all the atomic sites. The building unit of the crystal structure of phosgenite is represented by a Pb-polyhedron, in which Pb is coordinated by 5Cl + 4O (coordination number CN = 9), forming a monocapped square antiprism. The combination of face-sharing Pb-polyhedra generates dense layers parallel to (001), which are connected by (edge-sharing) CO3-groups to form the crystalline edifice. Low-T neutron diffraction data show evidence of a temperature-mediated phase transition towards a lower symmetry (space group P$\bar 4$), with a modest distortion of the building units of the structure. A tentative description of the low-T mechanisms, at the atomic scale, that can lead to the phase transition is provided.

The high-T behaviour of phosgenite proves this mineral is stable at least up to 523 K, at which the first evidence of transformation (with the coexistence of phosgenite + Pb2O2Cl, and probably an amorphous phase) takes place. The XRD pattern at 548 K unveils a more complex scenario, with coexisting: phosgenite (dominant) + Pb2O2Cl (minor) + mendipite [Pb3O2Cl2] (minor) + Pb5O2Cl6 (subordinate) (+ amorphous phase). This phase composition is preserved up to 648 K, after which phosgenite is no longer preserved, and the stable compounds are: mendipite [Pb3O2Cl2] (dominant), Pb2O2Cl (subordinate) + Pb5O2Cl6 (subordinate) + kutnohorite-type [Ca(Mn,Mg,Fe2+)(CO3)2] (likely, very minor) (+ amorphous phase). The same assemblage is observed up to 698 and back to 298 K after a decrease in T, showing an irreversible transformation of the pristine material. Therefore, the irreversible temperature-induced degradation of phosgenite is substantially governed by a decarbonation process.

A new hydrous aluminium sulfate mineral sarvodaite, Al2(SO4)3·5H2O, was discovered at the tract of Kukhi-Malik, Fan-Yagnob coal deposit, ca. 75 km N of Dushanbe, Tajikistan. Sarvodaite is a fumarolic mineral formed directly from gas from a natural underground coal fire. Associated minerals are anhydrite, realgar, native selenium and several unknown phases. The mineral typically occurs as white spherulites of thin colourless prismatic crystals up to 500 μm in maximum dimension. Sarvodaite is optically biaxial, α = 1.529(2), β = 1.537(2), γ(calc.) = 1.545(3) (590 nm), and the measured 2V is 90(3)°. The measured density is 2.33(2) g/cm3. The mineral is non-soluble in water and ethanol and dissolves slowly at room temperature in HCl. The composition of sarvodaite was studied using EDS. Raman and IR spectroscopy confirmed the presence of H2O. The empirical formula calculated on the basis of 17 O atoms per formula unit is (Al1.88Fe0.06Ti0.04)Σ1.98S3.01O12·5H2O. Sarvodaite is monoclinic, P21/n, a = 5.4862(4), b = 10.8029(8), c = 20.8413(15) Å, β = 96.416(7)°, V = 1227.46(16) Å3 and Z = 4. The structure of sarvodaite contains three symmetrically independent Al sites and three S site. Al-centred octahedra and sulfate groups form strongly corrugated layers interconnected via hydrogen bonding. Sarvodaite has a synthetic analogue. Infrared and Raman spectra are reported. Sarvodaite is the third hydrous Al sulfate mineral species without additional cations and anions to be described to date, following alunogen, Al2(SO4)3·17H2O and meta-alunogen, Al2(SO4)3·12H2O.

Tennantite-(In), Cu6(Cu5In)As4S13, was approved as a new mineral species from the Pefka epithermal ore deposit, Alexandroupolis, Evros, Western Thrace, Greece. It was identified as anhedral grains, up to 0.1 mm in size, intimately associated with roquesite, galena and tennantite-(Fe) in quartz gangue. In reflected light, tennantite-(In) is isotropic, pale grey in colour. Reflectance values for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 31.2; 546: 30.7; 589: 30.5; 650: 28.8. Electron microprobe analysis gave (in wt.% – average of 7 spot analyses): Cu 43.83(95), Mn 0.22(8), Fe 0.65(46), Zn 0.57(12), Cd 0.16(5), Pb 0.26(2), As 14.38(3.00), In 5.05(59), Sb 7.74(3.08), Te 0.48(9), S 26.18(79), total 99.52(78). The empirical formula of the sample studied, recalculated on the basis of ΣMe = 16 atoms per formula unit, is Cu10.82In0.69Fe0.18Zn0.14Mn0.06Cd0.02Pb0.02As3.01Sb1.00Te0.06S12.81. Tennantite-(In) is cubic, I$\bar 4$3m, with a = 10.285(2) Å, V = 1088.1(6) Å3 and Z = 2. The five strongest reflection lines in the calculated powder X-ray diffraction pattern are [d in Å, (I), hkl]: 2.969, (100), 222; 2.571, (20), 400; 1.878, (7), 521; 1.818, (42), 440; and 1.551, (21), 622. The crystal structure of tennantite-(In) has been refined by single-crystal X-ray diffraction data to a final R1 = 0.0253 on the basis of 240 unique reflections with Fo > 4σ(Fo) and 23 refined parameters. Tennantite-(In) is isotypic with other members of the tetrahedrite group. Indium is hosted at the tetrahedrally coordinated M(1) site, in accord with the known preference of this element for tetrahedrally coordinated bonding environments.

Here we present the first single-crystal X-ray diffraction analysis of zolenskyite, a chromium-bearing sulfide mineral (FeCr2S4) and newly identified polymorph of daubréelite, discovered in the Muonionalusta meteorite, a well-characterized IVA iron meteorite. Zolenskyite occurs as rare micron-scale grains associated closely with daubréelite and stishovite, within a troilite matrix. Chemical analysis confirms a pure, homogeneous FeCr2S4 composition. The crystal structure was refined in the monoclinic C2/m space group, revealing a framework of face-sharing octahedra, consistent with a cation-deficient NiAs-type structure, distinct from the spinel-type structure of daubréelite. Zolenskyite forms under high-pressure (>7 GPa) and high-temperature (>1000 K) conditions, probably through solid-state transformation from daubréelite during shock events. The serendipitous recognition of zolenskyite emphasizes the value of careful micron-scale mineralogical investigations in revealing transient or metastable phases that record otherwise inaccessible physicochemical conditions. These findings contribute to understanding the thermal and shock history of meteorite parent bodies and the stability of Fe–Cr sulfides in extraterrestrial environments.

Fanfaniite, Ca4Mn2+Al4(PO4)6(OH)4·12H2O, from the Hühnerkobel pegmatite mine, Bavaria, has been characterised by chemical analyses and synchrotron single-crystal diffraction. The average crystal structure was refined in space group C2/c (cell parameters a = 10.055(2), b = 24.132(5), c = 6.2590(10) Å, β = 91.35(3)°) to compare with reported monoclinic structures of other calcioferrite-group minerals with general formula Ca4AB4(PO4)6(OH)4·12H2O, A = Mn2+, Fe2+, Mg, B = Al, Fe3+. The average structure contains disordered half-occupied A sites and associated coordinated water molecules. The diffraction data for fanfaniite contains weak reflections that violate the c-glide condition, as also reported for montgomeryite, and in addition contains extremely weak, diffuse reflections requiring a doubling of a, as reported for kingsmountite. Structure refinements were conducted for the noncentrosymmetric C2 model used for montgomeryite and for the P$\bar 1$ model used for kingsmountite. The fanfaniite diffraction data is better explained by the triclinic model with doubled a cell parameter, although the extent of ordering of the A-site cations is considerably lower (56%) than reported for kingsmountite (85%). If the C2 model contributes, it can only be at the scale of the unit cell.

This study reveals the mineralogy and origin of unusual silica-carbonate bodies (listvenite) associated with tectonized serpentinites and Permian–Triassic phyllites from the Tokat region in northern Turkey. The listvenite includes green-coloured opaline silica intersected by saddle dolomite and minor sulfide mineralization (pyrite, cobaltite and enargite). It also hosts abundant chalcedonic bodies, i.e. agate of bluish to bluish-white colour. Listvenite-hosted opaline silica has been recognized as lussatite, a fibrous birefringent opal-CT variety, with a dominantly ‘tridymitic’ structure. The green colouration results from discrete, but widely disseminated, Cr-bearing smectite-group minerals, such as volkonskoite and/or Cr-montmorillonite. Chromium, the main colouring agent as determined by element-distribution mapping and visible-light spectroscopy, was probably derived from spinel-group minerals (e.g. chromite), the relics of which mark the presence of an ultramafic protolith. In contrast, the vein agate is composed of length-fast chalcedony, with subordinate quartzine and minor opaline silica, followed by drusy quartz. Its bluish colour appears to be related to scattering effects enhanced by elevated moganite contents (up to 46 wt.%). The observed mineral paragenesis suggests at least a two-stage evolution: (1) early listvenitization marked by carbonate-silica alteration of the host serpentinite together with concomitant sulfide precipitation; and (2) subsequent silicification producing chalcedony (agate) veins under low-temperature conditions, followed by possible dissolution of the earlier saddle dolomite. This evolution reflects complex fluid–rock interactions involving CO2-rich, Ca-bearing and later Si-rich fluids under fluctuating redox and pH conditions. Hence, the proposed crystallization sequence of the associated mineral assemblage is: sulfides (cobaltite+pyrite+enargite) → saddle dolomite → opal (lussatite) + Cr-smectite → chalcedony (agate). These data provide new insights into the genesis, colouration mechanisms and structural state of Cr-bearing opaline and chalcedonic silica in altered ultramafic terrains.

Erionite is a naturally-occurring zeolite mineral series with a fibrous-asbestiform shape, that has been linked to malignant mesothelioma due to its high biopersistence and respirability. Despite its potential health risks, its occurrence, variability and environmental significance in New Zealand remain poorly understood. This study aims to better understand the occurrence of erionite by investigating its geological settings, crystal chemistry, and morphological variability. A total of 138 samples were initially screened for erionite occurrence, from which three localities were selected for detailed characterisation: Kaipara, Auckland, and Mount Somers, representing erionite-Na, erionite-Ca and erionite-K, respectively. A comprehensive stepwise analytical approach was employed, initially using PXRD and SEM-EDS for phase identification and morphological analysis. Where erionite was identified, further analysis was conducted using TEM-3DED, micro-Raman and EMPA. Results reveal that palaeoenvironmental conditions influence erionite’s crystal habits and composition, occurring as prismatic aggregates, acicular bundles and woolly asbestiform fibres. Many of the fibres met the World Health Organization (WHO) respirability criteria, highlighting potential health risks if airborne. Although bulk concentrations are relatively low, the presence of respirable fibres in both rural and urban settings raises concerns regarding potential environmental exposure during earthworks and construction. This study establishes the link between erionite’s geological setting and morphology. Providing essential data to inform environmental monitoring, land-use planning and risk mitigation in areas where erionite-bearing rocks may be disturbed.

The crystal structure of jungite from the Hagendorf Süd pegmatite, Bavaria, has been determined using synchrotron diffraction data collected at the Australian Synchrotron microfocus beamline MX2.

The mineral has orthorhombic symmetry, space group Aba2, with cell parameters a = 11.995(2), b = 24.692(5) and c = 9.920(2) Å. The structure was refined to wRobs = 0.063 for 3558 reflections with I > 3σ(I). It is built from double heteropolyhedral layers parallel to (010) with [Ca(H2O)6]2+ hydrated cations and H-bonded H2O in the interlayer region. The heteropolyhedral layers comprise seven-member rings of corner-connected ZnO4 and PO4 tetrahedra and Fe3+2O10 dimers of edge-shared octahedra. From the refined structural model the formula is established as [Ca(H2O)6]2Zn4Fe3+8(PO4)8(OH)12(H2O)4·4H2O. The jungite specimen also contains crystals that indexed with triclinic cell parameters, a ≈ 11.95, b = 10.05, c = 9.9 Å, α ≈ 86.7, β =89.9 and γ = 83.4°. They gave poor diffraction due to multiple components with different orientations, but it was possible to extract intensity data for a single component and solve the structure. The model contains identical double heteropolyhedral layers parallel to (010) as in the orthorhombic mineral, but differs in that the Ca atoms are coordinated predominantly to layer anions. The formula obtained from the structural model is [Ca2(H2O)5]Zn4Fe3+8(PO4)8(OH)12(H2O)4·2H2O, corresponding to a dehydrated form of jungite, with a contraction in the layer spacing from 12.35 to 10.0 Å.