European Deposits Research Articles

Environmental aspects of remote sensing for the classification of asbestos industry impact on the landscape changes in Cyprus

Abstract. The Industrial Revolution led to the commercial exploitation of asbestos in Cyprus. Cyprus has the second largest asbestos deposits in Europe, after Italy. Even though most of the extracted asbestos was exported, Cyprus had two operational asbestos manufacturing plants. Production increased steadily until 1980, with mining activities ending in 1988. These activities have left a significant mark on the environment. The key example of post-asbestos landscape in Cyprus is the opencast mine at Amiandos in the Limassol District, where large amounts of asbestos were mined. This has had a considerable impact on the natural environment and land use including the disposal of asbestos residues and asbestos-cement waste. Temporal analysis of land use changes from 1963 to 2014 reveals shifts in exploitation areas and vegetation cover. Though challenges persist, including asbestos-containing waste, efforts to restore vegetation in the mine area are evident. The evolution from sparse and undeveloped vegetation to a lush and diverse ecosystem is important for restoring ecological balance and restoring habitats for local fauna and flora. This research provides critical insights into the historical context, environmental impacts, and remediation efforts related to asbestos mining in Cyprus.

The first recognition of the enigmatic fossil shark genus Megalolamna (Lamniformes, Otodontidae) from the lower Miocene of Europe and M. serotinus (Probst, 1879) as the newly designated type species for the genus

Megalolamna is an elusive extinct shark genus (Lamniformes: Otodontidae) previously known from the upper Oligocene–Miocene of the USA, Colombia, Ecuador, Peru, and Japan. Here, we document the first occurrence of Megalolamna from Miocene marine deposits in Europe, specifically from Austria, France, Germany, and Italy. Although the taxon is regarded as a monospecific genus, this study reveals that the species name serotinus has the priority over any previously used names for the taxon and thus redescribes it as Megalolamna serotinus (Probst), comb. nov. This study is also significant because it demonstrates the existence of Megalolamna in the Mediterranean and Paratethys seas during the Miocene. Megalolamna inhabited the tropical–mid-latitudinal zones with spotty but wide geographic distribution.

Land snail Δ47 thermometry using cultured and European natural populations of Clausilia pumila, Succinella oblonga and Trochulus hispidus

Clumped isotope composition (Δ47) of aragonitic shells of terrestrial molluscs allow the quantitative reconstructions of continental paleotemperatures from loess-paleosol records of the last 2.5 million years, but it needs testing the method under controlled laboratory conditions and using natural populations. In this study the stable carbon, oxygen and clumped isotope compositions of cultured individuals and field-collected specimens of three species (Clausilia pumila, Succinella oblonga and Trochulus hispidus), widespread in Quaternary loess deposits in Europe, were measured in the Debrecen (ATOMKI) and ETH Zürich laboratories. Our data of cultured snails demonstrate that shells of the three species record Δ47 signatures close to equilibrium conditions with mostly positive (C. pumila), both positive/negative (T. hispidus), and mostly negative (S. oblonga) offsets on the order of 0.0158 ± 0.0105 ‰ (mean offset±1 SD) compared to the Anderson et al. (2021) unified calibration. Calcification temperatures (TΔ47) derived from C. pumila shells were found to be in excellent agreement with chamber temperatures of 12, 18 and 24 °C, especially in the ATOMKI laboratory (mean T offset: 2.1 ± 2.2 °C, 1 SD), while the other two species exhibited larger discrepancies on the order of 5–8 °C (mean offset). Single shell-based mean TΔ47 values of field-collected molluscs indicated growth temperatures spanning values from the frost-free period to summer season, or even above summer maxima. The sites of natural populations, characterized by different climate conditions, could be grouped using the aridity index (AI) with values of 0.96–1.06 representing mean temperature of the frost-free period (TFFP), and AI ranging either from 0.85 to 0.91 or 1.14 to 1.51 reflecting mean summer season or July temperatures (TJJA/TJ). Multi-shell TΔ47, obtained by homogenizing the material of 3–5 shells of C. pumila and T. hispidus, reflect TJJA in most cases. We observed a dependence of the shell oxygen isotope compositions of the three species on oceanity/continentality with more negative/positive values characteristic for more continental/oceanic sites, likely due to moisture source distance and depletion of rainfall in 18O towards the continental interior. In addition, deviation of body fluid δ18O values (derived from δ18Oshell and Δ47shell) from seasonal precipitation δ18O is also controlled by an additional temperature effect, being independent of the climate zone of the collection site, but co-varying with the site-specific difference between single shell TΔ47 and TJJA.

Trace and Minor Element Analysis of Azurite Blues in Fine Arts: Possibilities and Limitations in Provenance Studies.

Azurite, a historical blue mineral pigment, has previously been described to contain certain elemental impurities. These may originate from host rocks, vein fillings, or the primary copper ore mineralization. In this study, azurites (and also green malachites) from three important Central European deposits with a potential of being exploited for pigment usage already in the Middle Ages have been studied, together with azurite from Chessy, France, with a different geological setting. Using electron probe microanalysis and, more importantly, laser ablation inductively coupled plasma mass spectroscopy for trace elemental analysis, several indicators were pinpointed as important for provenance: characteristic elemental fingerprint of the deposit, e.g., elevated lead (Pb) in combination with rare earth elements, may be combined with zinc (Zn)/arsenic (As) ratio (indicating sources of excess Zn in the primary deposit) and the overall amount of metal impurities (suggesting the source mineral of copper for azurite formation). In addition, malachites from the same deposits were found to preferentially incorporate primary ore metal elements as well as Cd, Mg, Mn, or U. Therefore, if azurite pigment contains an elevated amount of malachite as an impurity, it may significantly influence the overall elemental composition. The results obtained on geological samples were applied to two micro-samples of works of art containing azurite-rich layers originating from the 13th-14th and 16th centuries. It was shown that it is highly beneficial to focus on the overall trace elemental composition of the paint layer and not on the admixed mineral grains, as their presence, especially in minute micro-samples, is largely accidental and thus not representative. Although a higher number of samples need to be studied in the future, the newly described criteria made it possible to exclude some of the localities of the employed azurite pigment. This confirmed the key importance of trace elements analysis of mineral pigments for the provenance studies of fine arts.

Early Eocene fish otoliths from the eastern and southern USA

A collection of 1149 otoliths of the Ypresian and Ypresian–Lutetian transition (early Eocene) from 18 sites across five states in the eastern and southern regions of the USA was analyzed. In total, 33 otolith-based taxa are documented, of which 27 are identified at the species level. Nine of these are introduced as new species: “Conger” biaculeatus sp. nov., Bauzaia gibbosa sp. nov., Ampheristus brevicaudatus sp. nov., Symmetrosulcus virginicus sp. nov., Neobythites longesulcatus sp. nov., “Neobythites” pamunkeyensis sp. nov., “Neobythites” stringeri sp. nov., Waitakia dorsogibbosa sp. nov., and “Haemulon” ypresiensis sp. nov. The assemblages are distinct when compared to their younger Eocene counterparts in America. This distinction is primarily characterized by the high proportion of the newly introduced species or exclusive Ypresian species. Additionally, we highlight the presence of 10 amphi-Atlantic species originally described in European deposits. Significantly, the composition of the otolith collection supports the interpretation of a shallow-water environment for the sampled sites during the Ypresian. This ecological setting appears to persist into the subsequent middle and late Eocene within the same geographic region.

Formation of Topaz-Greisen by a Boiling Fluid: A Case Study from the Sn-W-Li Deposit, Zinnwald/Cínovec

Abstract Zinnwald/Cínovec is one of the largest Li-Sn-W greisen deposits in Europe. Greisens in general are important hosts for many major ore deposits of several high-tech elements—most prominently Sn, W, and Li. However, the mechanisms of greisenization in relationship to ore formation are still not well understood, especially for the important case of fluoride-rich greisen. Here, we investigate the sequence and formation mechanism of the topaz-greisen in the Zinnwald/Cínovec deposit. Based on the mineral abundances, the alteration profile can be divided into four distinct zones: (1) rhyolite, (2) albitite, (3) low-degree greisen, and (4) high-degree greisen. In the greisen zones, almost all the feldspar has been replaced by topaz (up to 12 vol %) + quartz (up to 78 vol %), and the abundance of mica gradually decreases from 11 to 3 vol % with increasing degree of greisenization. Mass balance calculations indicate a net influx of F and silica during greisenization. Our observations are best explained by a two-stage greisenization process involving phase separation by boiling in the pore space of the sample: first an acidic HF-rich phase, likely a vapor, reacted with feldspar to form topaz and quartz in a dissolution-precipitation reaction. This reaction created substantial transient porosity, which was subsequently sealed by the precipitation of quartz and fluorite from a boiling liquid. We interpret the vapor and liquid as emerging from a common supercritical aqueous parental fluid. The characteristic sequence of creation of pore space by a vapor and the subsequent reduction of porosity by precipitation from the associated boiling liquid constrain the conditions and time available for ore formation. This study evaluates the mechanism of topaz greisenization and the controls on porosity evolution, which are crucial to ore element redistribution.

A redescription of Trachelosaurus fischeri from the Buntsandstein (Middle Triassic) of Bernburg, Germany: the first European Dinocephalosaurus-like marine reptile and its systematic implications for long-necked early archosauromorphs

Some of the earliest members of the archosaur-lineage (i.e., non-archosauriform archosauromorphs) are characterised by an extremely elongated neck. Recent fossil discoveries from the Guanling Formation (Middle Triassic) of southern China have revealed a dramatic increase in the known ecomorphological diversity of these extremely long-necked archosauromorphs, including the fully marine and viviparous Dinocephalosaurus orientalis. These recent discoveries merit a reinvestigation of enigmatic Triassic diapsid fossils from contemporaneous European deposits housed in historical collections. Here, we provide a redescription of Trachelosaurus fischeri, represented by a single, disarticulated specimen first described in 1918. Due to its unique morphology, which includes short, bifurcating cervical ribs, and a high presacral vertebral count, this taxon has been referred to either as a “protorosaurian” archosauromorph or a sauropterygian. Our revision clearly shows that Trachelosaurus represents the first unambiguous Dinocephalosaurus-like archosauromorph known from outside the Guanling Formation. Our finding has important systematic implications. Trachelosauridae Abel, 1919 represents the senior synonym for the recently identified Dinocephalosauridae Spiekman, Fraser and Scheyer, 2021. Based on our phylogenetic analyses, which employ two extensive datasets, we also corroborate previous findings that tanystropheids and trachelosaurids represent two families within a larger monophyletic group among non-crocopodan archosauromorphs, which is here named Tanysauria (clade nov.). Trachelosauridae is minimally composed of Trachelosaurus fischeri, Dinocephalosaurus orientalis, Pectodens zhenyuensis, and Austronaga minuta, but one of our analyses also found a probably taxonomically broader clade that may also include Gracilicollum latens and Fuyuansaurus acutirostris. Trachelosaurus fischeri considerably expands the known spatial and temporal range of Trachelosauridae to the earliest Anisian and the Central European Basin. Our findings add to the growing evidence for the presence of a diverse group of fully marine reptiles during the Middle Triassic among Tanysauria. These trachelosaurids possess flipper-like limbs, high vertebral counts, and elongate necks, thus superficially resembling long-necked Jurassic and Cretaceous plesiosaurs in some regards.

The first unique‐headed bug (Hemiptera, Enicocephalomorpha) from Cretaceous Iberian amber, and the Gondwanan connections of its palaeoentomological fauna

AbstractEnicocephalomorpha, also known as unique‐headed bugs, are a seldom‐collected infraorder of heteropteran insects whose evolutionary relationships have puzzled entomologists for more than a century. Unique‐headed bugs are exceptionally rare in the fossil record, which hinders our understanding of the morphological transformations of the lineage across time and also affects the calibration of molecular clock estimates used to date the origins of the infraorder. Here, we report the discovery of Enicocephalinus ibericus sp. nov. from Iberian amber in the Ariño deposit in Spain, early Albian (Early Cretaceous) in age. The new species represents the second oldest fossil enicocephalomorphan to date, and the second record of this infraorder from European deposits. Remarkably, the closest relative of E. ibericus is the congeneric E. acragrimaldii Azar from Lebanese amber that is c. 20 myr older (Barremian), indicating a long‐term persistence of the Enicocephalinus lineage across geological time. A review of the existing literature enabled us to record a total of 20 congeneric insect species that have been found in both Lebanese and Iberian ambers, suggesting the existence of previously underappreciated entomofaunal connections between southern Laurasia (the European archipelago) and northern Gondwana during the Cretaceous. We show that the palaeoentomological record holds remarkable potential for elucidating the faunistic exchanges and palaeobiogeographical patterns in the peri‐Tethyan region during the Cretaceous.

New record of the conifer wood taxon Brachyoxylon from the Middle Jurassic in southwestern China, and a global survey of paleobiogeography of the Mesozoic Brachyoxylon occurrences

Fossil wood is one of the most important proxies for terrestrial vegetation composition and continental paleogeographical reconstruction in Earth's history. The conifer wood Brachyoxylon is commonly found in Mesozoic deposits in Europe, Africa, South America, and Antarctica with more than one hundred known occurrences to date. However, only few occurrences (∼5%) are so far documented in China of East Asia. Here, we describe a fossil wood specimen from the Middle Jurassic Upper Shaximiao Formation at Yongxin of Chongqing City in southeastern Sichuan Basin, China, exhibiting typical Brachyoxylon anatomy with mixed radial tracheid pitting and araucarioid cross-field pitting. According to the characters of radial tracheid pitting, cross-field pitting, and ray height, the wood is recognized as Brachyoxylon trautii (Barale) Philippe 1995. To better understand the paleobiogeography of the Mesozoic Brachyoxylon, a global survey of its occurrences is performed, which shows that Brachyoxylon was globally expanding over time with the widest geographic distribution in the Cretaceous.

Early-stage application of process mineralogy methodologies for mineral tracking in flotation of rare earth elements (REE)-bearing minerals from a deposit in Norway

The Fen carbonatite complex, situated in Vestfold and Telemark County, South Norway, is one of the largest known rare earth elements (REE) deposits in Europe with ongoing exploration drilling. Literature regarding the complex processing of the Fen ore is lacking, and thus, the present work investigates for the first time its beneficiation potential and applies process mineralogy studies to understand in a sound manner the performance variations during the processing of REE ore. Flotation kinetics studies revealed that (i) high concentration of total REE-oxide (TREO) can be achieved during rougher flotation; (ii) the high concentration of sulphur (in form of pyrite as main sulphide) can be achieved at the beginning of flotation; (iii) the highest concentration of TREO can be reached after flotation of S. Further processing (i.e., by the addition of cleaning stages and grinding) has a potential to improve the overall recovery of TREO and S. However, the decision of further processing will depend, among other factors, on the definition of following hydrometallurgical routes (e.g., leaching, solvent extraction) and the economic aspects of the overall process. So far, the reported results show that a rather flexible process can be achieved for the material from the Fen deposit.

Abundance and Genetic Significance of Lithium in Karst-Type Bauxite Deposits: A Comparative Review

Palaeo weathering during the Cretaceous–Eocene interval is most favorable for bauxitization, i.e., transport and deposition in traps on the karstified surfaces of the Mediterranean karst bauxite belt, including the Parnassos–Ghiona bauxite deposit. Resources of lithium (Li), a critical metal of strategic significance in karst-type bauxite deposits, have attracted significant attention in recent years. Due to the discovery of the Li enrichment in certain karstic bauxite deposits in Europe and particularly in China, this review study is focused on the unexplored Li content in the Parnassos–Ghiona (Greece) bauxite deposit, aiming to improve the understanding of the major controlling factors for their origin and enrichment of critical metals. The presence of thin (up to 50 cm) pyrite-bearing coal seams and carbonaceous facies on top of the Parnassos–Ghiona bauxite deposit, at the transition between B3 (the youngest) bauxite horizon and the occurrence of multicolor bauxite ores reflecting a multistage evolution and changes in the mineralogy and geochemistry, is a common feature with other bauxite deposits in Europe and elsewhere. The organic matter, such as microorganisms in coal layers and carbonaceous layers (derived from plants and algae growing in paleo-mires after a regression of the sea), contains Li, which is derived from seawater, as suggested by a positive correlation with B (a seawater component as well). The available geological, mineralogical, and geochemical data highlight the particular significance of coal layers and carbonaceous layers overlying bauxite bodies as a driving force for redox reactions and as a source of Li in the exploration of karst-type bauxite deposits.

Facies and Origin of Tufa Deposits from the Gostilje River Basin and the Sopotnica River Basin (SW Serbia)

Tufa accumulations from the Gostilje River Basin and the Sopotnica River Basin in SW Serbia are represented by both active and fossil tufa precipitates. The aim of this study is to distinguish and describe different tufa facies and to determine the environmental conditions, based on stable isotope data. We also compare our analysis with other tufa deposits in Europe. Four facies are distinguished: moss tufa, algal tufa, stromatolitic laminated tufa, and phytoclastic tufa. The dominant constituent of all tufa samples is low Mg-calcite, whereas the presence of sylvite is noted in two samples from the Gostilje River Basin. The δ18O values range from −9.07‰ to −10.79‰ (mean value: −9.81‰), while the δ13C values range from −6.50‰ to −10.34‰ (mean values −9.01‰). The stable isotope values (δ13C and δ18O) indicate that these tufa deposits were precipitated from cold, ambient water supported by CO2 of an atmospheric origin. We emphasize that this is the first data about stable isotope analyses of tufa deposits from Serbia.

Petrophysical Database for European Pegmatite Exploration—EuroPeg

Granitic pegmatites contain natural concentrations of a variety of raw materials invaluable for modern technologies and a green and sustainable society. The most abundant ones are silicon for high-purity quartz applications, and indispensable lithium for today’s batteries. However, the exploration of these target materials in Europe is underdeveloped, causing high dependencies on non-European supply chains. The European Commission Horizon 2020 project GREENPEG (GA no. 869274) is addressing the exploration of buried, small-scale pegmatite deposits in Europe through the development of innovative new exploration toolsets. One component of these toolsets is petrophysical data of pegmatite ores and their wall rock. These data are essential to supplement and ground-truth non-invasive geophysical investigations and deposit modeling. Both important tools in mineral exploration can then be used in a more targeted and cost-effective way. Petrophysical parameters measured on drill core and field samples and acquired through geophysical borehole logging are compiled in the first database for European Pegmatite deposits: EuroPeg_PetroDB. Samples are supplemented with meta-information, and the database is comprehensively structured in an easy-to-use format. Supporting the initiative of FAIR data, EuroPeg is freely accessible on an open data repository. The sample content and petrophysical measurements are described, followed by the structure and usability of the database.

The Hoatzin

Joel Cracraft introduces the Hoatzin (Opisthocomus hoazin), an odd and enigmatic bird that defies classification.

The elemental sulfur ore deposit of Salmerón: Las Minas de Hellín basin (Late Miocene, SE Spain)

Strata-bound elemental sulfur deposits occur in different circum-Mediterranean Miocene sedimentary successions containing evaporites and high amounts of organic matter. It is widely known that bacterial sulfate reduction processes are the triggering mechanisms involved in the origin of hydrogen sulfide and the subsequent native sulfur. However, in most of these sedimentary successions, there is controversy over whether elemental sulfur formed in the basin floor, as the same time as the sediments (biosyngenetic), or later, during diagenesis (bioepigenetic). Las Minas de Hellín basin, in the SE Spain, contains one of the largest elemental sulfur deposits in Europe. Based on data recovered from mining company (1903 -1960) and a borehole campaign performed by MINERSA between 1987 and 1988, two native sulfur ore bodies are recognized. The upper sulfur body is hosted by carbonates and diatom-rich levels, whereas the lower sulfur body, only exploited in underground mines now closed, is hosted by gypsum. This work shows a petrological and geochemical study of core samples from the upper sulfur body in the Salmerón area (Murcia), 500 m west of the widely exploited area of Las Minas de Hellín (Albacete). In Salmerón, elemental sulfur occurs as pseudomorphs after primary sedimentary gypsum as well as filling fractures and bed joints. The elemental sulfur replacement is also related to calcification and silicification of the sedimentary biomediated dolomite. The mineralization is considered bioepigenetic formed during early diagenesis. Contribution from hydrothermal waters circulating through adjacent faults are not ruled out.

The potential for REEs in igneous-related apatite deposits in Europe

Abstract Phosphate rocks and rare earth elements (REEs) as potential by-products are listed as Critical Raw Materials (CRMs) by the European Commission. In Europe, igneous-related phosphate deposits are associated with carbonatites, alkaline complexes, (ultra)mafic intrusions, iron oxide–apatite (IOA) and iron oxide–copper–gold (IOCG) mineralization, and granites or are formed in a metasomatic/hydrothermal context. To provide an overview of these deposits and assess their potential in CRMs, a database gathering in situ analyses of apatite was compiled. The data emphasize the significant REE enrichment of apatite related to alkaline complexes and carbonatites. They also guide the use of apatite in mineral exploration, based on distinct geochemical characteristics. Among the latter are the Sr, Mn, total REE and Y contents of apatite, the degree of light and middle REE enrichment, the Eu anomaly, and the tetrad effect. Additional bulk-rock analyses combined with estimates of reserves/resources of the deposits indicate a sub-economic potential of REEs to be exploited as by-products of phosphate mining at Kodal, Bjerkreim–Sokndal and in the northern Norrbotten district (Sweden). This study helps to identify new deposits/areas of interest for CRM exploration in Europe that could contribute to decreasing the supply risk for these raw materials through domestic production.

Geochemistry of surface waters around four hard-rock lithium deposits in Central Europe

There are several Li-mica and spodumene deposits in Central Europe. The Cínovec deposit on the border of the Czech Republic and Germany is the largest known hard-rock Li deposit in Europe and is currently being explored. Weathering and mining of such deposits could release Li and F to the environment. Both elements are associated with potential health effects when ingested via drinking water, yet little is known about the aqueous geochemistry of streams and creeks around Li hard-rock deposits. In this study, we sampled surface waters (n = 47) near three Li-mica and one spodumene deposit to examine a potential public health risk resulting from the weathering of Li-minerals. At the Cínovec and Homolka (also in the Czech Republic) sites, several water samples have elevated Li contents relative to those in typical surface waters, but they are all below the U.S. EPA-recommended threshold of 0.7 mg/L. Three of the ten samples from Cínovec contain F in concentrations that are above World Health Organization's 1.5 mg/L drinking water limit, and thus these waters (max. concentration: 3.8 mg/L) may represent a public health hazard. Based on geochemical modeling and statistical analysis, the lithium in the water comes from Li-micas and the fluoride is derived from a combination of Li-micas and fluorite, depending on the specific site analyzed. Lithium seems to be scavenged by clay minerals.

Private Bank Deposits and Macro/Fiscal Risk in the Euro-Area

We examine the relationship between private bank deposits and macro/fiscal risk in the euro area. We test three hypotheses: First, private bank deposits relative to Germany are determined by macro/fiscal risk factors. Second, this relationship is time-varying. Third, time-variation is driven by the level of macro/fiscal risk. Our findings validate all three tested hypotheses. They also reveal persistent fragmentation between EMU core and periphery banking systems caused by a deficit of trust in periphery banking systems, unmitigated by the introduction of OMT and European Banking Union. Our findings have implications for the introduction of the European Deposits Insurance Scheme (EDIS), for which they offer tentative support.

Feasibility of using clays from Southeast European deposits in limestone calcined clay cements

Recently, the cement industry has faced new challenges in addition to the environmental constraints of the last decade. The decline in availability and current inconsistent prices of common supplementary cementitious materials (SCMs), such as by-products from the iron industry or coal-fired power plants, have opened the search for more reliable materials. Research on cements containing calcined clays now serve as a possible solution to the forementioned problems. Clays containing the mineral kaolinite in sufficient quantities, when calcined and mixed with limestone powder, produce hydration products that can improve the strength and durability of concrete. In addition, the production of limestone calcined clay is reported to be less CO2 intensive, but this eco-efficient solution is viable only if the materials are locally available. For this reason, this study investigates the possibility of using natural clays from the Southeast European region (SEE) as cement replacements. A systematic experimental study was conducted on 18 different clays from 13 different deposits to determine the physical and mineralogical composition of the raw clays, their reactivity and mortar strength. The results were then related to the environmental contributions they might have in comparison with ordinary Portland cement in concrete.

Nepheline Syenite as an Alternative Source for Aluminum Production

The increasing demand for aluminum in conjunction with the limited available bauxite deposits in Europe results in the dire need for the evaluation of alternative raw materials for the whole value chain of alumina production. The present paper focuses on the possible use of nepheline syenite, originated as a mine byproduct, in alumina production through leaching with an azeotropic HCl solution. Previous work on nepheline syenite dissolution focused more on the extraction of potassium and sodium values. In this work, emphasis is given at the characteristics and leachability of aluminum content phases by applying a high temperature HCl leaching in untreated material. From this point of view, leaching experiments were conducted on nepheline syenite, at a temperature range of 90 °C to 150 °C and with aqueous azeotropic HCl solution. Leaching, in the aforementioned conditions, is a process, characterized by medium aluminum dissolution. The results show that the aluminum-bearing phases that withstand the dissolution process are mainly the ones of sodium and potassium feldspars.