ABSTRACT We investigated the possible use of bog iron ores in late prehistoric and early historic times (c. 800 BCE–750 CE) from a landscape-archaeological perspective, using archaeology, soil science, hydrology and geochemistry, connecting data from raised bogs and adjacent dryland areas. Raised bogs were not hostile, but provided food and a place for ritual activities. Little is known, however, on the potential exploitation of iron ores in these landscapes. We compared bog iron ores in the raised bog of the Bourtangermoor (the Netherlands) with ores on the adjoining Drentian plateau, inhabited since prehistoric times as possible sources of iron. We compared bog iron ore mineralogy, its mode of deposition, and the ease of finding and excavating it to settlement locations and archaeological finds related to iron-working remains. Based on secondary evidence, we concluded that only bog iron ores on the Drentian plateau were used, but not the iron deposits associated with the raised bog.

Since the dawn of human civilization, discovery of metals, especially iron (Fe), has played a pivotal role in the growth and diversification of human societies and industries. Steel, a metallurgical engineering marvel, is considered the backbone of any economy. Despite the immense importance and demand, Fe supply chains are highly compromised. The dominance of low-grade ores and highly positive carbon footprint of Fe ore processing presses demand green technologies like biomining. Understanding the intricate mechanisms by which microbes encourage mineral dissolution is pivotal in bioleaching. This study addresses a critical knowledge gap by examining the ability of Pseudomonas aeruginosa to mobilize Fe from mineral (ferrihydrite, goethite, and hematite) and rock surfaces (basalt glass and crystalline basalt), selected to mimic the mineralogy of critical and oxide Fe ores, such as laterites. Fe acquisition poses challenges to P. aeruginosa due to its limited availability in diverse environments. To overcome this limitation, bacteria employ sophisticated strategies, including synthesizing and secreting siderophores, small molecules with a high affinity for Fe, to scavenge and uptake Fe effectively. In this study, we investigated the role of siderophores in facilitating Fe uptake from various Fe sources by P. aeruginosa. Experimental setups involved incubating Fe oxides and basalt separately in sterilized Teflon flasks containing an Fe-limiting growth medium, each inoculated with a P. aeruginosa strain. Results demonstrated a significant increase in extracted Fe when siderophores were present, indicating a siderophore-driven process in Fe mobilization. Our findings highlight the complex regulatory network governing Fe mobilization in P. aeruginosa, emphasizing the interplay between quorum sensing (QS) and the Fe sequestration system. Unraveling these molecular mechanisms advances our understanding of microbial Fe acquisition strategies and opens avenues for understanding the innovative survival strategies employed by bacteria in Fe-limiting environments. Such studies are important for scaling up ferredox (a biohydrometallurgical concept for oxide ores) biomining processes for industrial use.

Volcanogenic Massive Sulfides (VMS) are considered major base (Cu-Zn±Pb) and precious metal (Au and Ag) sources with paramount contribution in the development and evolution of mankind through the ages. They are characterized by variable ore mineralogy and geochemistry, largely attributed to the variety in the geotectonic regime of formation (both divergent and convergent margins) and the variability in the host lithologies. Several VMS types are distinguished depending on the type of volcanism and host-rock lithology. The lens-shaped-to-stratiform bodies composed of fine-grained sulfides, usually accounting for more than 60% of the rock mass, have been exploited since prehistoric times. Recent studies reveal that VMS continue to be formed in deep marine settings and along plate margins on the ocean floor. Besides base and precious metals, nowadays, VMS are considered significant sources of critical and strategic metals, such as Co, Ni, Ga, Ge, In, Bi, As, Sb, Se, Mo, Cd, Sn, Hg, Tl and Bi, particularly after extensive research of the ocean floors in the years following World War II (WWII). Since the late 1970s, the potential of VMS has been further enhanced after the successful deep-sea mining (DSM) pilot tests, with the pipeline-lift mining system considered the most suitable for seabed massive sulfide (SMS) recovery.

Abstract. Lopatkaite, ideally Pb10As2Sb6S22 (Z=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 Rmin/Rmax values based on the standard wavelengths (Commission on Ore Mineralogy, COM): 37.0 % / 39.3 % (470 nm), 34.1 % / 36.9 % (546 nm), 33.1 % / 36.2 % (589 nm), and 31.3 % / 34.1 % at (650 nm). The average result of four electron probe microanalyses for the structurally investigated grain is as follows (in wt %): Pb 57.81(4), As 3.53(8), Sb 20.03(6), S 19.08(6), and total 100.46(22), corresponding to Pb10.28(3)As1.74(4)Sb6.06(3)S21.92(3) (based on 18Me + 22S = 40 atoms per asymmetric unit). The density calculated using the empirical formula is 6.168 Mg m−3. Single-crystal X-ray diffraction data show lopatkaite to be monoclinic, space group P21/c (no. 14), with a=8.0806(6), b=23.3597(18), c=21.4880(16) Å, β=100.7090(10)°, V=3985.4(5) Å3, and Z=4. The seven strongest lines in the (calculated) powder diffraction pattern are as follows (d in Å (intensity) (hkl)): 3.728(39) 211, 3.712(100) 035, 3.653(35) 062, 2.804(41) −261, 2.780(43) 260, 2.779(38) −262, and 2.020(47) −402. The ideal formula is in accordance with the results of the crystal structure analysis, Pb10.336As1.567Sb6.088S22 , and may be derived from the ideal boulangerite formula, Pb10Sb8S22 (Z=4), by means of substitution of two Sb atoms with two As atoms. Lopatkaite is an isotype of boulangerite, differing by dominant As occupancy at two crystallographically independent mixed (Sb, As) sites. This dominant-site substitution defines lopatkaite as the arsenic-dominant isotype of boulangerite and justifies its recognition as a distinct mineral species. Lopatkaite is also a new member of the rod-based family of sulfosalts.

The accelerating transition to low carbon energy systems has intensified the demand for nickel and cobalt from low-grade (<1.5 wt.%) refractory lateritic ores. These low-grade laterites are however not amenable to conventional beneficiation due to their complex mineralogy, eclectic physicochemical properties, and fine Ni–Co dissemination. This review examines recent advances made in the extraction of nickel and cobalt from complex low-grade lateritic ores, emphasizing the interplay between ore mineralogy, chemistry, beneficiation, pretreatment, and processing route selection. Developments in selective ore comminution–classification have led to the generation of Ni-rich fine fractions (undersize) and Co-rich coarse fractions (oversize), enabling differentiated extraction strategies that improve resource utilization, frugal energy use, and process efficiency. Mechanical activation via stirred media milling, thermal calcination-induced structural disorder, and dehydroxylate goethite products, are shown to significantly enhance Ni–Co leaching kinetics under both atmospheric and heap leaching conditions. A critical comparison of pyrometallurgical (rotary-kiln electric furnace) and hydrometallurgical (HPAL, EPAL, heap, atmospheric, bioleaching) routes demonstrates that ore-specific optimization is essential to balance recovery, acid consumption, and greenhouse gas emissions. The novel resin in moist mix (RIMM) process, which integrates ambient leaching and in situ ion exchange selective recovery, is shown to offer potential for sustainable values extraction from sub-economic resources. Furthermore, the review highlights the key innovation challenges and concomitant opportunities for enhanced critical battery metal recovery from complex laterite ores.

• Varying pyrite feed grade and water quality studied simultaneously in flotation. • Higher feed grade and ionic strength of process water increased froth stability. • Depressant dosage improved pyrite grades by reducing non-floating gangue recovery. • No clear effect of feed grade or water quality on Fe recovery. • Developed relationships linking feed grade, water quality, and flotation performance. Flotation systems are complex, multifaceted and water intensive. Process operators are becoming increasingly aware that detrimental process water quality and variations in ore mineralogy can affect the overall process efficiency. The depletion of ore feed grades with respect to valuable minerals further complicates the concentration of ores through froth flotation. Although evidently critical, ore feed grade and water quality are in most cases not controlled, thereby rarely investigated together as varying parameters. This study seeks to develop an understanding into the effects of varying ore feed grade on gangue recoveries, froth stability and flotation performance under different water qualities. Batch flotation results showed solids and water recovered increased with feed grade all depressant dosages and ionic strength of plant water. Higher feed grades and ionic strengths generally resulted in the most stable froth as indicated by solids and water recoveries. The Fe recoveries were within a similar range of ∼80 to 94 % for all feed grades suggesting that there was not much influence on Fe recoveries either the feed grade, ionic strength of plant water or depressant dosage was varied. Increasing the feed grade led to an increase in Fe grades at all depressant dosages and synthetic plant water types. The highest Fe grade was about ∼27 % for 3 % pyrite feed < 34 % for 6 % pyrite feed grade < 35 % for 12 % pyrite feed. Furthermore, this increase was not directly proportional to the hydrophobic component. Finally, Fe grades increased in conjunction with depressant dosage at each pyrite feed grade for all synthetic plant water types, owing to the reduction in NFG reporting to the concentrate, which dilutes the grade. Overall, flotation performance was enhanced as measured by the solids and water recoveries, froth stability and grade.

Abstract New results are reported for the thermally assisted beneficiation of three low-grade iron ores (LGIOs) with varying hematite-to-goethite (HG) ratios (0.1 to 3), using both rapid high-flux radiation heating (10 to 40 °C/s) and slow convective heating via thermogravimetric analysis (TGA, 0.1 °C/s). Experiments were conducted in the 300 °C to 700 °C range to systematically assess for the first time how heating rate and ore mineralogy influence thermal decomposition, phase transformation, and beneficiation performance under novel high-flux radiation-assisted conditions. The LGIOs, initially containing 51.5 to 55 wt pct Fe, showed mineral-dependent behavior under fast heating conditions. At 700 °C, nearly full conversion was found for samples with HG = 0.1 and 1 while high ore conversion (~ 80 pct) was found for HG = 3, regardless of the heating rate, though high-flux radiation method allowed to achieve conversion significantly faster. Under high-flux radiation, decomposition and goethite-to-hematite transformation occurred within minutes, producing highly porous hematite with elevated surface area and limited recrystallization. Nevertheless, the extent of goethite dehydroxylation at a given temperature in the range of 300 °C to 500 °C, found to decrease with an increase in heating rates &gt; 10 °C/s, showed that the chemical conversion time can also be a rate-limiting factor. For samples with HG = 0.1 and 1, the heating rate strongly affected the resulting ore microstructure at 500 °C to 700 °C, with high-flux radiation treatments providing up to 50 pct greater surface area than the slow-heated samples. When coupled with magnetic separation, the high-flux radiation method yielded Fe grades of 58 to 61 wt pct and Fe recoveries of 50 to 90 pct depending on ore type. Overall, the results demonstrated the strong coupling between ore mineralogy and heating rate on both microstructural changes and beneficiation performance.

Abstract The new minerals auropolybasite, ideally Ag15AuSb2S11, and auropearceite, ideally Ag15AuAs2S11, were found at the Šibeničný vrch near Nová Baňa in Slovakia. They were found as anhedral grains up to 0.2 mm in size, usually rimmed by acanthite. Both new minerals are associated with acanthite, argentopolybasite, argentopearceite, pyrargyrite, proustite, stephanite, selenostephanite, rozhdestvenskayaite-(Zn), zvěstovite-(Zn), zvěstovite-(Fe), naumannite, Au-Ag alloys, uytenbogaardtite, iodargyrite, and bromargyrite. They are dark grey to black, opaque, with a black streak and metallic luster. The Mohs hardness is ∼3. They are brittle with no observable cleavage and with a conchoidal fracture. The calculated densities are 6.622 g/cm3 for auropolybasite and 6.606 g/cm3 for auropearceite. In reflected light, auropolybasite and auropearceite are gray with a bluish tint, no observable bireflectance, and very weak pleochroism. They show moderate anisotropy in crossed polars with weak greenish and green-blue tints. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the IMA are (Rmin/Rmax, %): 33.5/31.6 (470 nm), 32.9/31.1 (546 nm), 32.1/30.6 (589 nm), and 30.2/29.3 (650 nm) for auropolybasite and 30.6/29.8 (470 nm), 30.3/29.2 (546 nm), 29.7/28.7 (589 nm), and 28.1/27.4 (650 nm) for auropearceite. The empirical formula (based on 29 apfu) for auropolybasite is Ag15.27Au0.84(Sb1.51As0.46)Σ1.97(S10.55Se0.30Cl0.06)Σ10.91 and that for auropearceite is Ag15.84Au0.88(As1.33Sb0.44)Σ1.76(S10.46Se0.05Te0.01)Σ10.52. The ideal end-member formulas are Ag15AuSb2S11 for auropolybasite and Ag15AuAs2S11 for auropearceite. Their symmetry is trigonal, space group P321. Latice parameters for auropolybasite are: a = 15.1091(5) Å, c = 12.1518(5) Å, V = 2402.42(15) Å3, Z = 4, and those for auropearceite are: a = 14.995(3) Å, c = 12.115(2) Å, V = 2359.3(8) Å3, Z = 4. Crystal-structure analysis of auropolybasite confirmed that its atomic arrangement is isotypic to that of the other members of the polybasite group and it is isostructural with auropearceite. These minerals formed in the waning stages of epithermal systems, where reduced, S-rich, low-salinity fluids transported Au, Ag, Sb, and As as thiocomplexes. These fluids were unable to transport Cu, Pb, and Zn, thus explaining the chemical composition of these minerals and the entire mineral assemblage.

Abstract. Keutschite, Cu2AgAsS4, is a new mineral from the Ag–Pb–Zn deposit at Uchucchacua, Oyon District, Catajambo, Lima Department, Peru. The mineral occurs as metallic, highly lustrous, blocky, free-standing crystals measuring up to 3 mm. These crystals exhibit a grey colour with a slight green-brassy tint and a grey-black streak, and they are present on both manganoquadratite and proustite. It was observed that keutschite was brittle, and no fractures or cleavages were identified. In plane-polarised light, keutschite exhibits a grey hue devoid of any discernible internal reflections. It demonstrates a minimal manifestation of pleochroism and exhibits a negligible degree of bireflectance. Between crossed polars, the mineral is weakly anisotropic with rotation tints in shades of greenish grey to grey. Reflectance measurements in air yield the following Rmin/Rmax values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association: 25.2/26.1 (470 nm), 29.6/29.4 (546 nm), 29.4/29.2 (589 nm), and 28.5/28.6 (650 nm). Keutschite crystallises in a tetragonal geometry and is classified as space group I4‾2m. The unit cell parameters are as follows: a=5.5834(15), c=10.021(3) Å, V=312.40(14) Å3, a:b:c=1:1:0.897, and Z=2. The crystal structure was refined to R1=0.0199 for 286 reflections with I&gt;3σ(I). The structure of keutschite is derived from that of sphalerite by ordered substitution of Zn atoms, analogous to the substitution pattern for deriving stannite from sphalerite. The crystal structure of the mineral can be derived from that of luzonite through the complete substitution of one of the two copper sites with silver. The five strongest intensities in the X-ray powder diagram are [d in Å (intensity) hkl]: 3.101 (100) 110; 2.792 (11) 200; 1.974 (20) 220; 1.665 (34) 204; and 2.846 (27) 312. The chemical formula, as determined by electron microprobe analysis, is Cu2.05Ag0.96(As0.95Sb0.04)Σ0.99S4.00 (based on eight atoms). The ideal formula, derived from the crystal structure, is Cu2AgAsS4. The name honours Frank Keutsch (born 1971) for his contribution to the mineralogy of the Uchucchacua deposit.

Abstract Economic concentrations of rare earth element (REE) minerals are uncommon in the Earth’s crust, with most occurring in carbonatites. Unlike most igneous rocks composed of silicate minerals, carbonatites are dominated by carbonate minerals, some of which can incorporate substantial light REEs (LREEs; La, Ce, Pr, Nd). Technological applications of REEs are numerous, and they have been identified as some of the most critical mineral commodities to the global economy. The Mountain Pass carbonatite stock in the Mojave Desert of California is the most economically significant REE deposit in the U.S.A. It contains a few to tens of percent (by volume) of the carbonate REE ore mineral bastnäsite. Despite the economic significance of the Mountain Pass deposit, studies of its ore mineralogy are limited. Here, we present new carbonate ore mineralogy data for a compositionally diverse suite of carbonatitic rocks from the Mountain Pass stock and related dikes. Whole-rock geochemical data are integrated with mineral-scale textural and chemical data obtained by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and microRaman spectroscopy. Our results document a complex spectrum of REE-bearing carbonate minerals and intermediate mixed-layer structures. Mineral species include bastnäsite [REE(CO3)F], hydroxylbastnäsite [REE(CO3)OH], parisite [Ca(REE)2(CO3)3F2], synchysite [Ca(REE)(CO3)2F], röntgenite [Ca2(Ce,La)3(CO3)5F3], and sahamalite [(Mg,Fe)(REE)2(CO3)4]. Carbonate ore mineralogy is heterogeneous within and between samples, including at the intracrystal scale. Complexly zoned crystals exhibit as many as five to six different compositional domains and syntaxial intergrowths, commonly with the more Ca-rich varieties (parisite, synchysite) forming crystal rims that surround relict bastnäsite cores. We attribute the phenocryst variability to changes in the chemistry and temperature of primary carbonatite magmas and evolved/exsolved fluids. Cross-cutting vein textures of calcite, celestine and various REE carbonate minerals, breccia blocks lined by fine-grained bastnäsite, and the presence of hydroxylbastnäsite and partially hydroxylated bastnäsite point to the role of secondary hydrothermal processes in REE mineralization. Fluorcarbonate mineral compositions demonstrate that La and Ce are more structurally abundant in bastnäsite, whereas parisite and synchysite contain a greater proportion of REE heavier than Pr (Nd, Sm, Eu, Gd) and Y. Atomic ratios of Pr/(Nd+Pr) are likewise variable, with the highest average value for bastnäsite (0.25) compared to parisite (0.22) and synchysite (0.21). This finding has geometallurgical implications, given that current mining operations are focused on recovering Nd and Pr for high field strength permanent magnets, and the Nd/Pr ratios are a critical factor in ore processing and magnet manufacture.

Impact of H2-enrichment and ore mineralogy on the reduction of varying iron ores in suspension smelting ironmaking

The rheological properties of iron ore tailings are essential to explore carefully for their sustainable applications in transport and disposal. The complex nature of tailings flow arises due to slurry concentration, fine particles, a wide particle-size distribution, and a diverse mineralogical composition. This study investigated and compared the rheological behavior of Indian iron ore tailings at various slurry concentrations, both with and without the addition of a flocculant, and its correlation with the tailings’ mineralogical characteristics and particle behavior. An iron ore tailing of Fe(T): 41.32%, SiO2: 36.57%, Al2O3: 1.65%, and LOI: 2.29% was taken for the current study, which contains 16.89% goethite & 4.17% kaolinite, and D80: 265 μm & D50: 66 μm. Rheological experimentations were conducted under varying slurry concentrations. The increase in slurry viscosity, shear stress, and strain with increasing solid concentrations was attributed to the population of particle-particle opposing relative motion and ore mineralogy. At low shear rates, the tailings slurry showed shear-thinning behavior. However, after a shear rate of 20 s−1 for all solid concentrations, it transitioned from shear thinning to a shear thickening behavior. The yield stress increases suddenly after 40 Wt.% of the slurry. The rheological behavior of the current slurry exhibits more Herschel–Bulkley fluidic properties than those of a Bingham plastic. The yield stress and apparent viscosity increased several times after adding a polyacrylamide flocculant to the same iron ore tailing slurry. However, once this threshold stress limit was exceeded, the slurry exhibited linearity in its shear stress and shear strain profiles, trending toward that of a Bingham fluid. An empirical correlation model was developed to calculate slurry viscosity by modifying previously available equations, incorporating ore mineralogy, with a root mean square deviation of 1.24. The current findings offer insights for pipeline design, slurry management, and promoting the sustainable utilization of Indian iron ore tailings.

This study investigates the mineralogy of skarn, ore, and wall rocks in the Kesikköprü Fe-skarn deposit, along with the behavior, distribution, and enrichment processes of major oxides and trace elements. It also evaluates the skarn-forming potential of the Kesikköprü granitoid for different metals. The Kesikköprü mineralization is linked to an endoskarn zone dominated by garnet-pyroxene (±phlogopite±epidote) and to an exoskarn zone, in which assemblages toward the wall rocks comprise garnet (±pyroxene±phlogopite), pyroxene (±garnet±phlogopite±epidote), epidote-garnet, and epidote. Magnetite mineralization is particularly found within the epidote-garnet and epidote exoskarn subzones. Mineralogical and geochemical data indicate a significant increase in iron content during the late stages of skarn formation. Geochemical and isocon-mass balance analyses demonstrate a strong protolith control on skarn formation. In the granitoids, the endoskarn formation is characterized by Ca-Fe-Mg-Mn-Si addition with Al and alkalis (Na, K) depletion, whereas marbles record Ca depletion accompanied by increasing Fe input toward the ore zones. Based on the genetic link between skarn-forming granitoids and associated metal types, the Kesikköprü granitoid is inferred to have the potential to generate not only Fe-skarns but also Cu- and partially Au- and Pb-Zn skarns. Given the regional mineralization, these findings suggest that the Kesikköprü granitoid has multi-metal potential worthy of further exploration.

Mineralogy and Texture of San Gabriel Ore: Statistical Analysis of Au and Ag in Sulfides and Oxides

Nanobubbles have recently been proposed as a promising technology to enhance mineral flotation; however, their behavior in real ores with complex mineralogy remains poorly understood. This study evaluates the effect of nanobubbles on the flotation of copper sulfide ores from Chilean porphyry deposits with contrasting clay contents. Two representative samples were analyzed: a low-clay-content ore (M1) and a high-clay-content ore (M2). Flotation tests were carried out in a 2.7 L forced-air cell, using kinetic experiments with and without nanobubbles and frother addition. The mineralogical composition was characterized by XRD and QEMSCAN, while SEM-EDS was used to analyze surface morphology and particle associations. The results showed that nanobubbles improved copper and molybdenum recoveries in M1 up to 7.5 and 20%, respectively, increasing both kinetics and final recovery, which was supported by SEM observations of clean surfaces and compact agglomerates. In contrast, in M2 the use of nanobubbles decreased flotation efficiency due to enhanced slime coating and the formation of non-selective agglomerates, which reduced the hydrophobicity of sulfide surfaces. Overall, this study demonstrates that the efficiency of nanobubbles strongly depends on ore mineralogy, offering advantages in clean systems but limitations in clay-rich ores, and highlights the need for mineral-specific strategies for their successful industrial application.

Reliable information on the chemical and physical makeup of mine tailings is critical in meeting environmental and regulatory requirements, as well as identifying whether contained elements, including critical minerals, might be economically recovered in future to meet growing demands. Detailed mineralogical characterization, supported by chemical assays and automated mineralogy (MLA) data on different size fractions, underpins a case study of flotation tailings from the processing plant at the Carrapateena mine, South Australia. The study provides valuable insights into the deportment of minor and critical elements, including rare earth elements (REEs), along with uranium (U). REE-minerals are represented by major phosphates (monazite and florencite) and subordinate REE-fluorocarbonates (bastnäsite and synchysite). More than half the REE-minerals are concentrated in the finest size fraction (−10 μm). REEs in coarser fractions are largely locked in gangue, such that economic recovery is unlikely to be viable. MLA data shows that the main REE-minerals all display specific associations with gangue, which change with particle size. Quartz and hematite are the most common associations, followed by sericite. Synchysite shows a strong affiliation to carbonates. The contents of other critical elements (e.g., tungsten, molybdenum, cobalt) are low and for the most part occur within other common minerals as submicron-sized inclusions or in the lattice, rather than discrete minerals. Nevertheless, analysis of mine tailings from a large mining–processing operation provides an opportunity to observe intergrowth and replacement relationships in a composite sample representing different ore types from across the deposit. U-bearing species are brannerite (associated with rutile and chlorite), coffinite (in quartz), and uraninite (in hematite). Understanding the ore mineralogy of the Carrapateena deposit and how the ore has evolved in response to overprinting events is advanced by observation of ore textures, including between hematite and rutile, rutile and brannerite, zircon and xenotime, and the U-carbonate minerals rutherfordine and wyartite, the latter two replacing pre-existing U-minerals (uraninite, coffinite, and brannerite). The results of this study are fundamental inputs into future studies evaluating the technical and economic viability of potentially recovering value metals at Carrapateena. They can also guide efforts in understanding the distributions of valuable metals in analogous tailings from elsewhere. Lastly, the study demonstrates the utility of geometallurgical data on process materials to assist in geological interpretation.

The new mineral zavyalovite, ideally Ag 2 TeS 3 , was found at the Boevskoe W-Be deposit, Chelyabinsk Oblast, Southern Urals, Russia.It occurs as very small anhedral grains (typically 5-15 m, max. up to 30 m across) or narrow veinlets (up to 100 5 m) within galena or at the contact of galena and sphalerite.Zavyalovite is dark red, opaque with sub-metallic luster, brittle tenacity and uneven fracture.No cleavage and parting are observed.The Vickers' micro-indentation hardness (VHN, 10 g load) is 95 kg/mm 2 (range 93-98, n = 4), corresponding to a Mohs' hardness of 2.5.D calc.= 5.33 g/cm 3 .In reflected light of the ore microscope, zavyalovite is grey, very weakly bireflectant and non-pleochroic.In crossed polarizers the new mineral exhibits strong anisotropy, in grey tones.Internal reflections are abundant, red in colour.The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are (R min /R max , %): 32.2/31.8(470 nm), 29.6/29.1 (546 nm), 28.4/27.5 (589 nm) and 27.3/26.5(650 nm).The Raman spectrum shows bands corresponding to stretching and deformation vibrations in the TeS 3 polyhedra.The chemical composition (wt.%, electron microprobe data, mean of 8 spot analyses) is Ag 49.31, Te 29.04, S 21.75, total 100.10.The empirical formula calculated on the basis of 6 atoms per formula unit is Ag 2.01 Te 1.

Abstract This study presents an in-depth analysis of thermally assisted beneficiation of a low-grade iron ore (goethite/hematite, 54.8 wt pct Fe) powder sourced from the Pilbara region in Western Australia. It was calcined in an electrically heated pilot-scale drop tube reactor (DTR) at relatively low temperatures (300 °C, 400 °C, and 500 °C), coupled with wet high-intensity magnetic separation to determine iron upgrade and recovery, and impurities removal. Various characterization techniques, including thermogravimetric analysis (TGA), X-ray diffraction, nitrogen adsorption, scanning electron microscope with energy dispersive X-ray spectroscopy, and X-ray fluorescence, were used to study the impact of flash heating on ore conversion, changes in ore mineralogy, and chemical-physical characteristics. It was found that the degree of conversion (calcination via goethite dehydroxylation) and mineralogy are strongly influenced by both heating rate ( HR ) and particle residence time ( τ ); samples heated under conditions relevant to flash heating in the DTR ( HR of 30 to 50 °C/s; τ in the order of minutes) exhibited different thermal decomposition behaviors to samples heated slowly in a TGA ( HR of 5 to 40 °C/min; τ in the order of hours). The analysis also shows that the proposed thermally assisted beneficiation method produces a hematite-rich concentrate with an iron upgrade and recovery of up to 60 wt pct and 94 pct Fe, respectively, and a high specific surface area (fivefold increase). Graphical abstract

Mineralogy, geochemistry, and petrogenesis of iron oxide-apatite ores in the Bafq mining district, Central Iran: Proposed a new tectonic setting for mineralization

Research subject. In morphological terms, the Bakayskoe gold occurrence comprises an area of fracture and crushing of sublatitudinal strike in the granitoids of the Turgoyak massif (C1-2), which contains quartz veins with sulfide mineralization. The vein zone is about 1.5 km in length. The Turgoyak massif is located on the border of the Magnitogorsk and Central Ural areas, being a satellite of the Syrostan massif.Materials and methods. Samples collected in old workings and ore stockpiles were studied by optical and SEM microscopy. Fluid inclusions in vein quartz were studied by thermoscryometry.Results. The predominant ore minerals were found to be pyrite and galena; rarely, the ores contain chalcopyrite, tetrahedrite, sphalerite, sulfosalts, and bismuth sulfotellurides. In the studied samples, gold is present as both native gold (primary and supergene), and tellurides and sulfides. Ores are partly oxidized. The average and median values of the homogenization temperature (Tg) of primary and primary-secondary inclusions from ore quartz are about 242– 247°C. The average and median Tg of quartz from shale is slightly lower (222 and 215°C, respectively), with a significant scatter of values. The concentration of salts in NaCl equivalent, determined by the melting point of the last ice crystal, varies from 1.4 to 13.0 wt % in FI from the host shales and 0.2–5.6 wt % in ore quartz. Such wide variations in salinity in all the studied cases may indicate changes in FI by secondary processes.