Mineral Species Research Articles

SOME CHARACTERISTICS AND CAUSES OF CHANGES IN THE RATE OF DISCOVERY OF NEW MINERALS SINCE 1800

ABSTRACT Construction of a discovery curve for Earth's minerals illustrates an abrupt inflection in rates of discovery and acceptance of new species that occurred in the middle of the 20th century. Prior to that time new mineral discovery is found to have accelerated at a modest pace of 0.3 species / year2. Since 1950 the rate of acceptance has accelerated at an average of 1.04 species / year2 such that the first two decades of the 21st century have been characterized by the acceptance of over 100 new minerals per year. Despite this rapid acceleration of discovery, the relative distribution among the 10 mineral classes of the Nickel-Strunz classification system of minerals identified prior to and after 1950 are nearly identical. Variation in the rates of attestation of the divisions, families, and mineral groups show distinct differences in that the maximum rates of discovery of minerals populating higher taxonomic levels occurred prior to 1950 while the attestation curve of newly recognized groups closely follows that defined by the identification of mineral species. The application of any hierarchical classification system to the mineral species is somewhat arbitrary and subject to biases or inconsistencies associated with the systematics of classification. Therefore, the discovery of new minerals is also considered within the context of the mathematically defined crystallographic space group symmetries. The space group attestation curve has a shape similar to those exhibited by the higher taxonomic levels within the Nickel-Strunz system. However, not all space groups are represented by naturally occurring minerals. Minerals discovered before and after the inflection in rates of new mineral discovery illustrate significantly different patterns of paragenesis. Nearly all of the species have been associated with one or more of 57 distinct paragenetic modes. Minerals that have long been known tend to have a higher number of paragenetic modes than those more recently discovered such that the average number of paragenetic modes is shown to have decreased linearly from 1950 to 2022. Further, the earliest known occurrence of over 80% of the currently accepted mineral species has been tabulated by the International Mineralogical Association. For species discovered prior to the inflection of 1950 a linear distribution of oldest ages is observed indicating that these minerals have earliest ages of occurrence that are uniformly distributed across the interval 0 to 4700 Ma. Conversely, approximately 70% of the species identified since 1950 have oldest known occurrences of less than 600 Ma and the age distribution of these post-1950 minerals exhibit an exponential distribution suggesting increasing efforts in new mineral discovery in tectonically active settings. Despite the differences in the pre- and post-1950 oldest age distributions, both populations exhibit similar temporal excursions in rates of new mineral creation that likely reflect substantial changes in Earth system processes responsible for new mineral formation.

Observationally constrained regional variations of shortwave absorption by iron oxides emphasize the cooling effect of dust

Abstract. The composition of soil dust aerosols derives from the mineral abundances in the parent soils that vary across dust source regions. Nonetheless, Earth system models (ESMs) have traditionally represented mineral dust as a globally homogeneous species. The growing interest in modeling dust mineralogy, facilitated by the recognized sensitivity of the dust climate impacts to composition, has motivated state-of-the-art ESMs to incorporate the mineral speciation of dust along with its effect upon the dust direct radiative effect (DRE). In this work, we enable the NASA Goddard Institute for Space Studies ModelE2.1 to calculate the shortwave (SW) DRE accounting for the regionally varying soil mineralogy. Mineral–radiation interaction at solar wavelengths is calculated according to two alternative coupling schemes: (1) external mixing of three mineral components that are optically distinguished, one of which contains embedded iron oxides; (2) a single internal mixture of all dust minerals with a dynamic fraction of iron oxides that varies regionally and temporally. We link dust absorption to the fractional mass of iron oxides based on recent chamber measurements using natural dust aerosol samples. We show that coupled mineralogy overall enhances the scattering by dust, and thus the global cooling, compared to our control run with globally uniform composition. According to the external mixing scheme, the SW DRE at the top of atmosphere (TOA) changes from −0.25 to -0.30Wm-2, corresponding to a change in the net DRE, including the longwave effect, from −0.08 to -0.12Wm-2. The cooling increase is accentuated when the internal mixing scheme is configured: the SW DRE at the TOA becomes -0.34Wm-2 with a net DRE of -0.15Wm-2. The varying composition modifies the regional distribution of single scattering albedo (SSA), whose variations in specific regions can be remarkable (above 0.03) and significantly modify the regional SW DRE. Evaluation against the AErosol RObotic NETwork (AERONET) shows that explicit representation of soil mineralogy and its regional variations reduces the low bias of model dust SSA while improving the range of variability across stations and calendar months. Despite these improvements, the moderate spatiotemporal correlation with AERONET reveals remaining modeling challenges and the need for more accurate measurements of mineral fractions in soils.

Reedmergnerite and stillwellite-(Ce) from the Dara-i-Pioz alkaline massif: insights into high-temperature behavior of borosilicates

Research subject. Reedmergnerite and stillwellite-(Ce) were obtained from the rocks of the Dara-i-Pioz alkaline massif located on the southern slope of the Alai Range in Tajikistan, which is characterized by the presence of rare mineral species including borosilicates and lithium minerals. Aim. To investigate the thermal behavior of reedmergnerite and stillwellite-(Ce) using high-temperature X-ray diffraction, including the determination of phase transition temperatures and expansion/compression of the unit cell parameters, as well as the calculation of thermal expansion coefficients. Materials and methods. Chemical analysis was performed using a TESCAN MIRA 3 microscope (EDS mode) and a JEOL JXA-8230 electron probe microanalyzer (WDS mode). High-temperature powder X-ray diffraction data were collected using a D8 ADVANCE Bruker diffractometer with an HTK16 heating chamber, covering temperatures from 30°C to 750°C in ambient air. Results. The thermal expansion coefficients of reedmergnerite and stillwellite-(Ce) were determined. Heating reedmergnerite resulted in slight changes in the unit cell parameters, with the parameter c experiencing the smallest change and the parameter a showing the greatest increase. The unit cell volume increased by 1.8% when heated to 750°C and returned to its initial value upon cooling. When stillwellite-(Ce) is heated in the temperature range of 400–450°C, a phase transition occurs, which is confirmed by previously recorded temperature values. The conducted heating and subsequent cooling experiments revealed that the volume and unit cell parameters of stillwellite-(Ce) did not fully revert to their original values. Conclusions. The coefficients of thermal expansion tensor (αij) of rhodmerdgnertite and stillwellite-(Ce) were investigated as a function of temperature using high-temperature in-situ experiments. The phases exhibited relatively low values of thermal expansion parameters compared to the general data for feldspars and borosilicates obtained from literature. These findings contribute to the understanding of the thermoelastic behavior of this group of minerals and their potential applications in various fields.

Estimating Modal Mineralogy using Raman Spectroscopy: Multivariate Analysis Models and Raman Cross-Section Proxies

Abstract Raman spectroscopy is a powerful technique in the context of planetary exploration because it provides mineral identification, chemistry, and abundance information. For Raman spectrometers with large spot sizes, multiple mineral phases can be investigated via the collection of a single Raman spectrum. There is a lack of methodology for quantifying mineral species in mixtures due to independent signal strengths of different materials in Raman spectra. Two techniques are presented in this work for the quantification of common rock-forming minerals: partial least squares multivariate analysis and a novel approach called Raman cross-section proxies (numerical metrics associated with specific Raman features). This paper targets 20 mineral species relevant to the mineralogy of the planet Mars. Mineral end-member samples and 187 binary mineral-mineral mixtures (mixture of two distinct minerals) are used for multivariate modeling. Eighteen diamond-mineral mixtures are used to derive Raman cross-section proxies. Mineral abundance proportions are predicted for the binary mineral-mineral mixtures with known mineralogical content to evaluate the efficacy of the two quantitative methods. Technique performance is mineral-dependent. The root-mean-square error for unseen predictions (RMSE-P) using Raman cross-section proxies ranges from ±3.2-17.0 volume%. For the multivariate models, the cross-validated root-mean-square error (RMSE-CV) ranges from ±8.8 to 26.2 volume%. Although these error estimates are not directly comparable, they provide the most accurate error estimate currently available. Different scenarios may favor the use of one or the other of the two quantitative methods. This work provides fundamental groundwork that can be applied to common rock-forming minerals on terrestrial planets including Mars. Quantification of mineral abundances aids in answering critical geologic questions related to ancient primary and altered rocks as well as planetary processes and conditions.

The Average Symmetry Index of Minerals Co-Varies with Their Hydrogen Content, Rarity, and Paragenetic Mode

Variations in the Dolivo-Dobrovol’sky symmetry index for minerals through time reveal several factors that influence the emergence of crystalline symmetry in natural processes. Of special interest in this regard are the numerous paragenetic modes—different processes of mineral genesis that reflect changes in physical, chemical, and ultimately biological environments that foster the emergence of new mineral species. Here, we consider the roles of hydrogen content, rarity, formation temperature and pressure, and age on the average symmetry of minerals from 57 different modes of formation (i.e., paragenetic modes). We find four significant trends in the average mineral symmetry index for all minerals in each paragenetic mode: specifically, this average index is (1) lower for minerals with greater hydrogen content; (2) greater for minerals formed at higher pressure; (3) lower for minerals of greater rarity; and (4) greater for older paragenetic modes. These findings elucidate some of the intricate relationships among paragenetic modes, average mineral attributes, and the Dolivo-Dobrovol’sky symmetry index, providing insights into the geological processes governing mineral formation.

Relation of bubble size, grade and recovery in the copper flotation systems

In recent years, studies have shown that bubble structure, which is affected by reagent types, dosages, and particle size, is closely related to flotation performance. In contrast to two-phase systems, there is very limited information regarding bubble size in three-phase systems. To this aim, we investigated the relationship between bubble size and flotation performance with two different copper ores. Firstly, the surface tension and bubble size measurements were carried out in two-phase systems with Methyl isobutyl carbinol, and Polypropylene glycol methyl ether. Then the bubble size measurements were performed in three-phase systems at laboratory and industrial scales. The results showed that surface tension decreased with higher frother amounts and higher pHs. Although remarkable decreases in bubble size were observed with increasing frother amount, a direct relationship between surface tension and bubble size was not observed. However, pH affected the behavior of the frother, resulting in smaller bubble sizes at pH 12 compared to pH 7. Similarly, the three-phase laboratory tests showed that higher amount of frother caused a reduction in the bubble size and the copper grade. Increasing the amount of collector also caused the bubble size and copper grade to decrease, but the frothers were more effective in bubble size reduction. Compared to the two-phase, in the three-phase study bubble size was notably bigger due to the presence of a collector and solid. In the plant scale, smaller bubble size and higher grade were obtained compared with the laboratory scale due to presence of cleaning circuit measurements. The froth phase properties were also affected by the ore types due to properties such as size and hydrophobicity of the various mineral species present.

Selective concentration of iron, titanium, and zirconium substrate minerals within Gregory's diverticulum, an organ unique to derived sand dollars (Echinoidea: Scutelliformes).

Gregory's diverticulum, a digestive tract structure unique to a derived group of sand dollars (Echinoidea: Scutelliformes), is filled with sand grains obtained from the substrate the animals inhabit. The simple methods of shining a bright light through a specimen or testing response to a magnet can reveal the presence of a mineral-filled diverticulum. Heavy minerals with a specific gravity of >2.9 g/cm3 are selectively concentrated inside the organ, usually at concentrations one order of magnitude, or more, greater than found in the substrate. Analyses of diverticulum content for thirteen species from nine genera, using optical mineralogy, powder X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, as well as micro-computed tomography shows the preference for selection of five major heavy minerals: magnetite (Fe3O4), hematite (Fe2O3), ilmenite (FeTiO3), rutile (TiO2), and zircon (ZrSiO4). Minor amounts of heavy or marginally heavy amphibole, pyroxene and garnet mineral grains may also be incorporated. In general, the animals exhibit a preference for mineral grains with a specific gravity of >4.0 g/cm3, although the choice is opportunistic and the actual mix of mineral species depends on the mineral composition of the substrate. The animals also select for grain size, with mineral grains generally in the range of 50 to 150 μm, and do not appear to alter this preference during ontogeny. A comparison of analytical methods demonstrates that X-ray attenuation measured using micro-computed tomography is a reliable non-destructive method for heavy mineral quantification when supported by associated analyses of mineral grains extracted destructively from specimens or from substrate collected together with the specimens. Commonalities in the electro-chemical surface properties of the ingested minerals suggest that such characteristics play an important role in the selection process.

New Mineral Names

Abstract This issue of New Mineral Names provides a summary of the newly described minerals from 2023 and selected information for recent descriptions from October to December of 2023. New mineral name trends and observations are presented using an objective, data-driven, and curated examination of new mineral species and their broader implications.

Eddavidite, Cu12Pb2O15Br2, a New Mineral Species, and Its Solid Solution with Murdochite, Cu12Pb2O15Cl2

Eddavidite is a new mineral species (IMA2018-010) with ideal formula, Cu12Pb2O15Br2, and cubic Fm3¯m symmetry: a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromine analog of murdochite, Cu12Pb2O15Cl2, with which it forms a solid solution series. The type locality is the Southwest mine, Bisbee, Cochise County, Arizona, U.S.A. Eddavidite also occurs in the Ojuela mine, Mapimí, Durango, Mexico. Eddavidite occurs as domains within mixed murdochite–eddavidite crystals. The empirical formula, normalized to 12 Cu apfu, is Cu12(Pb1.92Fe0.06Si0.06)(O15.08F0.02)-(Br0.99Cl0.89☐0.12). Type locality samples contain up to 67% eddavidite component, while Ojuela mine samples contain up to 62%. Mixed eddavidite–murdochite crystals show forms {100} and {111}; the habit grades from cubic through cuboctahedral to octahedral. Mixed eddavidite–-murdochite crystals exhibit good cleavage on {111}. Eddavidite is black, opaque with submetallic luster, and visually indistinguishable from intergrown murdochite. Its Mohs hardness is 4; dmeas. = 6.33 g/cm3, dcalc. = 6.45 g/cm3. The crystal structure, refined to R = 0.0112, consists of corner-sharing square planar CuO4 units, arranged in Cu12O24 metal oxide clusters, which encapsulate Br atoms. PbO8 cubes share edges with Cu12O24 clusters in a continuous framework. Eddavidite incorporates bromine remaining after desiccation of paleo-seawater at its two known localities, which were both once situated along the Western Interior Seaway.

Mineralogical Evolution of High-pH/Low-pH Cement Pastes in Contact with Seawater

In facilities for the geological disposal of radioactive waste in coastal areas, the long-term alteration of cementitious materials in engineered barriers is expected to occur due to the ingress of groundwater derived from seawater. Although the reaction between cement and seawater has been studied, the alteration behavior caused by the reaction between seawater and low-pH cement, which is expected to be used in a disposal facility, has not yet been clarified. In this study, the effects of cement type on cement–seawater interactions were investigated, and the chemical stability and mineral evolution of cement pastes caused by reactions with seawater were determined. The dissolution of cement hydrates occurred upon increased contact with seawater, and the formation of secondary minerals, including carbonate and Mg-containing minerals, was observed. The progress of dissolution depended on the mineral composition of the initially formed cement hydrates, and low-pH cement containing pozzolanic materials showed less resistance to seawater. Differences in pH and Si concentration that are due to the type of cement used had a strong influence on the evolution of minerals (especially Mg-containing minerals), implying that the formed mineral species possibly affect the migration characteristics of radionuclide.

Precise Measurement of Magnesium Isotopes in Fe‐Mg Minerals Using a Multi‐collector SHRIMP Ion Microprobe

The distribution of Mg isotopes in minerals is becoming increasingly relevant in Earth science. Usually, they are determined by dissolving mineral concentrates and, after purifying Mg with ion exchange resins, analysing the resulting solutions by TIMS or, most often, MC‐ICP‐MS. When applied to individual minerals, these methods are slow and prone to contamination from impurities in the concentrates, inconveniences that may be avoided using spot analysis techniques such as LA‐MC‐ICP‐MS or SIMS, albeit at the price of a large instrumental mass fractionation (IMF) and isobaric interferences, most prominent in the former. Here, we studied the potential of the multi‐collector SHRIMP II ion microprobe for measuring Mg isotopes in Fe‐Mg silicates and oxides. We found that, when corrected for the divergence of the Mg ion paths within the sample chamber caused by the Earth's magnetic field, the SHRIMP's IMF overwhelmingly depends on the mineral species, and the effects of variable chemical composition are negligible. We propose that the IMF is caused by the force constant difference, ∆F, between "hard" and "soft" bonds linking the ions of the studied element to the mineral lattice. Given that ∆F is a constant for each mineral species, we calculated IMF‐correction factors for the most common Mg‐bearing minerals. The thus‐calculated correction factors permit the analysis in the same session, and with reasonable accuracy (within ~ 0.3‰ of the δ26Mg determined by SN‐MC‐ICP‐MS analyses of concentrates), of samples from different mineral species, facilitating the application of Mg isotopes to terrestrial studies.

Principal component analysis of mineral and element composition of ores from the Bayan Obo Nb-Fe-REE deposit: Implication for mineralization process and ore classification

The Bayan Obo Nb-Fe-REE polymetallic deposit in northern China is the world’s largest light REE deposit. The deposit was formed through multiperiodic alteration and mineralization, and thus mineral species and assemblages are extremely complex. To date, there is still no consensus on the classification of ore types, and research on the paragenetic association of minerals is still inadequate. Eighty ore samples are divided into seven types according to altered minerals, including dolomite, iron oxide, aegirine, riebeckite, biotite, fluorite, and barite types. These samples were analyzed by a TESCAN Integrated Mineral Analyzer (TIMA) for their mineral and element composition. The data set was investigated by principal component analysis (PCA) to reveal the mineralization and alteration information and classify the ores.PCM1 to PCM3 and PCE1 to PCE3 represent the first three principal components for PCA results of minerals and elements, respectively. The results indicate that PCM1 may distinguish rare earth mineralization from barite and silicification alteration that is associated with the latest fluids. PCM2 can distinguish mineralization and alteration associated with Nb from those associated with REE. The combination of PCM2 and PCE1 indicates that the precipitation of REE may be closely related to fluorination and phosphate, while the combination of PCM2 and PCE3 indicates that the Nb mineralization may be more closely related to alteration of riebeckite and biotite, as well as to Ti-rich fluids. In addition, PCM3 distinguishes the Th mineralization and associated fluorination from other alteration and mineralization. Based on PCA results, the above seven ore types can be classified into three types: dolomite REE ore, Fe-REE-F ore, and Nb-rich ore, which provides a simplified and comprehensive classification for Bayan Obo ores. PCA-based approach combining geochemical and mineralogical data can quickly identify ore types, which is helpful in mineral exploration.

Heavy‐Mineral Grain Counting: Counting Techniques, Error Estimation, and the Number of Grains to be Counted

AbstractHeavy‐mineral assemblages of sediments and sedimentary rocks record information regarding provenance, including the source rocks involved, tectonic setting, climatic conditions, and modifications from source to sink. Drawing conclusions on provenance and provenance changes requires robust quantification of individual heavy‐mineral species contents, including error estimates. Nevertheless, it is common practice to count sub‐quantities of grains from aliquots and not considering the bias introduced by (a) counting similar numbers of grains from aliquots containing different total numbers of grains, and (b) using variable counting methods. Consequently, reported heavy‐mineral contents estimated from counting sub‐quantities are affected by errors of unknown extent, making it infeasible to determine whether intra‐ or intersample variations are statistically significant. Based on 65 heavy‐mineral aliquots of variable grain size, mineral species contents, total number of grains, and known composition determined by counting all grains (n = 80,393), here >31 million countings of heavy‐mineral sub‐quantities are simulated using (a) ribbon counting with varying ribbon size, ribbon position, ribbon orientation, total number of counts, and ways of aggregating counts from multiple ribbons, and (b) a newly proposed counting technique called cluster counting. I show that (a) error estimation for a specific aliquot requires a finite population correction; (b) compared to adjacent ribbons, aggregating counts of spatially distant ribbons reduces the error; (c) cluster counting further reduces the error, showing the best fit with theory; and (d) the Wilson score interval enables error calculation as well as the number of grains to be counted to achieve an operator‐specific aim.

An evolutionary system of mineralogy, Part VIII: The evolution of metamorphic minerals

Abstract Part VIII of the evolutionary system of mineralogy focuses on 1220 metamorphic mineral species, which correspond to 755 root mineral kinds associated with varied metamorphic rock types, most of which likely formed prior to the Phanerozoic Eon. A catalog of the mineral modes of 2785 metamorphic rocks from around the world reveals that 94 mineral kinds often occur as major phases. Of these common metamorphic minerals, 66 are silicates, 14 are oxides or hydroxides, 8 are carbonates or phosphates, 4 are sulfides, and 2 are polymorphs of carbon. Collectively, these 94 minerals incorporate 23 different essential chemical elements. Patterns of coexistence among these 94 minerals, as revealed by network analysis and Louvain community detection, point to six major communities of metamorphic phases, three of which correspond to different pressure-temperature (P-T) regimes of metamorphosed siliceous igneous and sedimentary rocks, while three represent thermally altered carbonate and calc-silicate lithologies. Metamorphic rocks display characteristics of an evolving chemical system, with significant increases in mineral diversity and chemical complexity through billions of years of Earth history. Earth's first metamorphic minerals 27 formed in thermally altered xenoliths and contact zones (hornfels and sanidinite facies) associated with early Hadean igneous activity (> 4.5 Ga). The appearance of new Hadean lithologies, including clay-rich sediments, arkosic sandstones, and carbonates, provided additional protoliths for thermal metamorphism prior to 4.0 Ga. Orogenesis and erosion exposed extensive regional metamorphic terrains, with lithologies corresponding to the Barrovian sequence of index mineral metamorphic zones appearing by the Mesoarchean Era (> 2.8 Ga). More recently, rapid subduction and rebound of crustal wedges, coupled with a shallowing geothermal gradient, has produced distinctive suites of blueschist, eclogite, and ultrahigh pressure metamorphic suites (< 1.0 Ga). The evolution of metamorphic minerals thus exemplifies changes in physical and chemical processes in Earth's crust and upper mantle.

Wenlanzhangite–(Y) from the Yushui deposit, South China: a potential proxy for tracing the redox state of ore formation

Abstract Mineral phases in which vanadium (V) and heavy–rare–earth elements (HREEs) coexist are rarely documented. Here, we report a new V–HREE–bearing silicate mineral species, wenlanzhangite–(Y), which is a vanadiferous derivate of jingwenite–(Y) [Y2Al2V4+2(SiO4)2O4(OH)4] coexisting with jingwenite–(Y) in bedded/massive ores at Yushui, South China. Wenlanzhangite–(Y) forms as a dark brown, 70–100 μm–thick rim on a core domain of jingwenite–(Y), which occurs as 100–200 μm columnar crystals. The colour, streak, lustre, and hardness (Mohs) are dark brown, yellow grey, vitreous, and ~4, respectively. Compared to jingwenite–(Y), wenlanzhangite–(Y) has higher vanadium and lower aluminium contents. Calculated on the basis of 8 cations, the empirical formula is (Y1.26Dy0.17Er0.11Gd0.09Yb0.09Nd0.09Sm0.06Sc0.04Ho0.03Ce0.02Tb0.02Tm0.02Pr0.01)Σ2.00(V3+1.46Al0.54)Σ2.00V4+2(SiO4)2O4(OH)4, which can be simplified to the ideal formula Y2V3+2V4+2(SiO4)2O4(OH)4. Wenlanzhangite–(Y) is triclinic, with space group P–1(#2), Z = 2, and unit–cell parameters a = 5.9632(7) Å, b = 9.599(1) Å, c = 9.9170(9) Å, α = 90.033(8)°, β = 98.595(2)°, γ = 90.003(9)°, and V = 561.28(10) Å3. Wenlanzhangite–(Y) is approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2022–142). The structure of wenlanzhangite–(Y) is composed of a–axis–oriented chains of [VO6] octahedra consisting of edge–sharing octahedra linked by insular [SiO4] tetrahedra, leaving open channels occupied by rare earth elements. Observed compositional variation and crystal structure demonstrate that V3+ can substitute for Al3+ in jingwenite–(Y), forming wenlanzhangite–(Y). The occurrence of wenlanzhangite–(Y) indicates a relatively more reducing hydrothermal environment causing reduction of V5+ in oxidized fluids to V3+ and thus represents a useful proxy for tracing the redox state of ore formation.

Testibiopalladite, PdSbTe: A Valid Mineral and Sb-Analogue of Michenerite

Abstract Testibiopalladite was reported from two unnamed deposits in China by Anonymous (1974) to be ideally PdSbTe. The description of the mineral included an indexed X-ray powder diffraction pattern, space group determination, electron probe micro-analyses, reflectance, and micro-indentation hardness measurements. This description was published without prior submission to the IMA, which was the norm at the time before China became a member. It is unknown as to why the Commission for New Minerals and Mineral Names (CMNMN) did not examine and vote on the mineral as had been done for all other Chinese mineral descriptions published at the time. It is surprising because the chairman of the CMNMN at the time had reviewed the mineral (Fleischer et al. 1976) and concluded it was a valid species, i.e., the Sb analogue of michenerite (PdBiTe). Further, the same article included a description of “hexastibiopanickelite” which was voted on and rejected by the CMNMN in 1976. From 1981 to 2021 there were many papers published reporting testibiopalladite from several deposits in different countries (e.g., Hudson et al. 1978, Chen et al., 1993, Stepanets et al. 2019, 2020), as well as a single-crystal structure analysis of synthetic PdSbTe which confirmed the assigned space group (Foecker & Jeitschko 2001). The published data (e.g., Barkov et al. 2002, Liang et al. 2019, 2023) suggest that testibiopalladite is a valid mineral species, ideally PdSbTe, and is the Sb analogue of michenerite, PdBiTe, both crystallizing in space group P213. Both the name testibiopalladite and the mineral, ideally PdSbTe, were approved by the Commission of New Minerals, Nomenclature and Classification of the International Mineralogical Association (CNMNC-IMA), Nomenclature Voting Proposal 23-H. Liang et al. (2019, 2023) studied samples from the type locality (Yangliuping deposit, PRC) that are to be considered as a neotype.

Comprehensive Study on Mineral Processing Methods and Mineral Technical Economics of Manganese Ore in Chongqing Chengkou.

Chongqing Chengkou manganese deposit is a large carbonate-type manganese deposit in the upper reaches of the Yangtze River, located in Gaoyan Town, Chengkou County, Chongqing. In order to improve the recovery rate of low-grade manganese ore and concentrate grade index, achieve efficient utilization of mineral resources, and sustainable development of Gaoyan manganese ore deposit in Chengkou, Chongqing, China, in this paper, by means of optical microscope analysis, high-resolution X-ray tomography technology, three-dimensional image analysis technology, X-ray diffraction analysis, X-ray fluorescence spectrum analysis, and technical and economic analysis, the occurrence state and process mineralogy of manganese are studied, and the technical and economic analysis of flotation, high-intensity magnetic separation, and gravity separation are carried out. It provides a reference for other mining enterprises to choose the most suitable beneficiation method according to the specific mineral species.

NATURALLY OCCURRING RADIONUCLIDES AND THEIR RADIOLOGICAL RISK ASSESSMENT IN RIVER SEDIMENTS FROM THE DITRAU ALKALINE MASSIF

Naturally occurring 238U, 232Th and 40K radionuclides within river bed sediments of Jolotca and Ditrău rivers from Ditrău Alkaline Massif (DAM) and their environmental risk and spatial distribution have been analyzed. The DAM metamorphic formations have been the subject of multiple studies due to their structure and high variety of mineral species. This led to the execution of many mining operations. River bed sediment samples have been collected from two of the main drainage basins of DAM, Ditrău and Jolotca rivers. The samples were analyzed using gamma-ray spectrometry in order to determine the concentration of the naturally occurring radionuclides and the risk parameters such as RLI (Representative level index), AGDE (Annual gonadal dose equivalent), Hex (External hazard index), Hin (Internal hazard index) and DR (absorbed gamma dose rates in air). 238U, 232Th and 40K show values higher than the Upper Continental Crust (UCC) and other studies from around the world. DR, AGDE and RLI are higher than the global average and the safe limits. These values are a consequence of the geological context which determined the presence of heavy minerals and Th and U bearing minerals.

Inherited Grain‐Size Distributions: Effect on Heavy‐Mineral Assemblages in Modern and Ancient Sediments

AbstractHeavy‐mineral suites are used widely in sandstone provenance and are key when connecting source and sink. When characterizing provenance related signatures, it is essential to understand the different factors that may influence a particular heavy‐mineral assemblage for example, chemical weathering or diagenetic processes. Hydrodynamics, causing size‐density sorting, exert major control on the distribution of heavy minerals. Here, we highlight the effect of grain‐size inheritance, essentially the absence of certain grain sizes within a specific heavy‐mineral species, on two distinct types of sediments. Modern deposits from a high‐energy beach in NW Denmark give an analog for heavily reworked sediment, primarily controlled by hydrodynamic processes. In contrast, three Palaeogene turbidite successions in the Eastern Alps were sampled, presenting a more complex history that includes diagenesis. All samples were processed for their heavy‐mineral compositions using Raman spectroscopy, and several techniques applied to determine the effect of grain‐size inheritance. Results show that (a) even within the hydrodynamically well‐sorted beach and placer deposits, evidence of grain‐size inheritance is apparent, and (b) turbidites of variable heavy‐mineral composition show strong effects of grain‐size inheritance for several mineral species. Moreover, considerable intersample contrasts within single turbidite beds are observed. We enforce the importance of understanding grain‐size inheritance, as well as other processes effecting size‐density relations in clastic sediment that go well beyond purely hydrodynamic control of intrasample heavy‐mineral variability.

Identifying sources of acid mine drainage and major hydrogeochemical processes in abandoned mine adits (Southeast Shaanxi, China).

Acid mine drainage (AMD) has resulted in significant risks to both human health and the environment of the Han River watershed. In this study, water and sediment samples from typical mine adits were selected to investigate the hydrogeochemical characteristics and assess the environmental impacts of AMD. The interactions between coexisting chemical factors, geochemical processes in the mine adit, and the causes of AMD formation are discussed based on statistical analysis, mineralogical analysis, and geochemical modeling. The results showed that the hydrochemical types of AMD consisted of SO4-Ca-Mg, SO4-Ca, and SO4-Mg, with low pH and extremely high concentrations of Fe and SO42-. The release behaviors of most heavy metals are controlled by the oxidation of sulfide minerals (mainly pyrite) and the dissolution/precipitation of secondary minerals. Along the AMD pathway in the adit, the species of Fe-hydroxy secondary minerals tend to initially increase and later decrease. The inverse model results indicated that (1) oxidative dissolution of sulfide minerals, (2) interconversion of Fe-hydroxy secondary minerals, (3) precipitation of gypsum, and (4) neutralization by calcite are the main geochemical reactions in the adit, and chlorite might be the major neutralizing mineral of AMD with calcite. Furthermore, there were two sources of AMD in abandoned mine adits: oxidation of pyrite within the adits and infiltration of AMD from the overlying waste rock dumps. The findings can provide deeper insight into hydrogeochemical processes and the formation of AMD contamination produced in abandoned mine adits under similar mining and hydrogeological conditions.