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![Diagram illustrating the critical metals according to EU reports [8] based on economic importance and supply risk (after Binnemans al. [22]).](profile/Ioannis-Tzifas/publication/334813895/figure/fig1/AS:786900440850432@1564623093072/Diagram-illustrating-the-critical-metals-according-to-EU-reports-8-based-on-economic.png)
Diagram illustrating the critical metals according to EU reports [8] based on economic importance and supply risk (after Binnemans al. [22]).
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The rare earth elements (REEs) are characterized by the European Union (EU) as critical raw materials with a significant risk of supply because of their broad utility in both traditional and emerging technological applications. The growing demand for REE has caused a flurry in the search for new REE deposits in Europe and elsewhere in the world, an...
Contexts in source publication
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... increasing demand for REEs and critical metals worldwide (Figure 1), as well as their uneven global distribution and apparent scarcity (most large active mines are located in China) has led the EU to encourage research for new REE deposits [8,9]. The region of Scandinavia as well as Greenland, host the majority of prospective REE deposits in EU, but research for new REE-bearing potential deposits is also in progress in other EU countries. ...
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... increasing demand for REEs and critical metals worldwide (Figure 1), as well as their uneven global distribution and apparent scarcity (most large active mines are located in China) has led the EU to encourage research for new REE deposits [8,9]. The region of Scandinavia as well as Greenland, host the majority of prospective REE deposits in EU, but research for new REE-bearing potential deposits is also in progress in other EU countries. ...
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... the heavy minerals present, allanite is the dominant REE-phase and thus controls the bulk REE signature. Xenotime, thorite, and monazite-being non-silicate minerals and thus relatively easier to extract REEs from their mineral structures-have also been identified, but they are found in relatively small concentrations ( Figure 10). Allanite from both the source granitoids and coastal sands of Mykonos have similar characteristics (e.g., zonation and composition), confirming the source control. ...
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... the heavy minerals present, allanite is the dominant REE-phase and thus controls the bulk REE signature. Xenotime, thorite, and monazite-being non-silicate minerals and thus relatively easier to extract REEs from their mineral structures-have also been identified, but they are found in relatively small concentrations ( Figure 10). Allanite from both the source granitoids and coastal sands of Mykonos have similar characteristics (e.g., zonation and composition), confirming the source control. ...
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... from local beaches have been investigated by Papadopoulos et al. [35]. These three localities lie within the Greek part of the Serbo-Macedonian Massif (SMM), a series of metamorphosed rocks, being sub-divided to Figure 10. Back-scattered electron images of selected heavy mineral grains separated from coastal sands from the Atticicycladic zone [63]. ...
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... coastal sands from Sithonia show relatively high REE content (15-6450 mg/kg) compared to the UCC (Figure 11). In particular, the LREE content ranges from 660 to 5810 mg/kg while the HREE content is much lower (3.1 to 9.8 mg/kg). ...
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... from the REE, other elements with notably elevated contents and thus potential economic interest are HFSE such as Nb (average 485 mg/kg) and Ta (average 39 mg/kg). Monazite, titanite, epidote, and allanite are the main mineral phases that influence significantly the REE and HFSE concentrations of the bulk sand samples studied (Figure 12). ...
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... 2019, 9, x [71], was followed by porphyritic intrusions and is linked to magmatic hydrothermal activity and the occurrence of various associated ore deposits [72]. All three localities (Ierissos, Ouranoupoli and Stratoni) are characterized by coastal mineral sands with no appreciable REE enrichment relative to the UCC average ( Figure 12). All studied samples are also depleted in LILE and HFSE, though Ierissos and Stratoni present significant enrichments in transition metals (As, Sb, Cu, Zn). ...
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... geochemical data, specifically chondrite-normalised REE spidergrams, are presented here for the Aggelochori region ( Figure 13 garnets in the heavy mineral fraction, along with abundant Ti-rich species. The coastal sands from Aggelochori are thus also enriched in HFSE such as Nb (134 mg/kg), Ta (10 mg/kg), Zr (4521 mg/kg), Hf (108 mg/kg) and Th (104 mg/kg). ...
Context 10
... three localities (Ierissos, Ouranoupoli and Stratoni) are characterized by coastal mineral sands with no appreciable REE enrichment relative to the UCC average ( Figure 12). All studied samples are also depleted in LILE and HFSE, though Ierissos and Stratoni present significant enrichments in transition metals (As, Sb, Cu, Zn). ...
Context 11
... geochemical data, specifically chondrite-normalised REE spidergrams, are presented here for the Aggelochori region ( Figure 13). Average HREE (65 mg/kg) and LREE contents (1280 mg/kg) are elevated compared to the respective values for coastal sands from Chalkidiki peninsula. ...
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... increasing demand for REEs and critical metals worldwide (Figure 1), as well as their uneven global distribution and apparent scarcity (most large active mines are located in China) has led the EU to encourage research for new REE deposits [8,9]. The region of Scandinavia as well as Greenland, host the majority of prospective REE deposits in EU, but research for new REE-bearing potential deposits is also in progress in other EU countries. ...
Context 13
... increasing demand for REEs and critical metals worldwide (Figure 1), as well as their uneven global distribution and apparent scarcity (most large active mines are located in China) has led the EU to encourage research for new REE deposits [8,9]. The region of Scandinavia as well as Greenland, host the majority of prospective REE deposits in EU, but research for new REE-bearing potential deposits is also in progress in other EU countries. ...
Context 14
... the heavy minerals present, allanite is the dominant REE-phase and thus controls the bulk REE signature. Xenotime, thorite, and monazite-being non-silicate minerals and thus relatively easier to extract REEs from their mineral structures-have also been identified, but they are found in relatively small concentrations ( Figure 10). Allanite from both the source granitoids and coastal sands of Mykonos have similar characteristics (e.g., zonation and composition), confirming the source control. ...
Context 15
... the heavy minerals present, allanite is the dominant REE-phase and thus controls the bulk REE signature. Xenotime, thorite, and monazite-being non-silicate minerals and thus relatively easier to extract REEs from their mineral structures-have also been identified, but they are found in relatively small concentrations ( Figure 10). Allanite from both the source granitoids and coastal sands of Mykonos have similar characteristics (e.g., zonation and composition), confirming the source control. ...
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... coastal sands from Sithonia show relatively high REE content (15-6450 mg/kg) compared to the UCC (Figure 11). In particular, the LREE content ranges from 660 to 5810 mg/kg while the HREE content is much lower (3.1 to 9.8 mg/kg). ...
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... from the REE, other elements with notably elevated contents and thus potential economic interest are HFSE such as Nb (average 485 mg/kg) and Ta (average 39 mg/kg). Monazite, titanite, epidote, and allanite are the main mineral phases that influence significantly the REE and HFSE concentrations of the bulk sand samples studied (Figure 12). Monazite and allanite apparently control the LREE enrichment, while zircon accounts for a significant fraction of the HREE abundance. ...
Context 18
... three localities (Ierissos, Ouranoupoli and Stratoni) are characterized by coastal mineral sands with no appreciable REE enrichment relative to the UCC average ( Figure 12 ...
Context 19
... geochemical data, specifically chondrite-normalised REE spidergrams, are presented here for the Aggelochori region ( Figure 13). Average HREE (65 mg/kg) and LREE contents (1280 mg/kg) are elevated compared to the respective values for coastal sands from Chalkidiki peninsula. ...
Context 20
... three localities (Ierissos, Ouranoupoli and Stratoni) are characterized by coastal mineral sands with no appreciable REE enrichment relative to the UCC average ( Figure 12). All studied samples are also depleted in LILE and HFSE, though Ierissos and Stratoni present significant enrichments in transition metals (As, Sb, Cu, Zn). ...
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Citations
... Karbonatit-előfordulások Törökországban és Olaszországban jelennek meg. Jelentős csoportot képviselnek a gumós monacithoz hasonlóan másodlagos telepek közé sorolt part menti torlatok, melyek főként Görögországra, Törökországra és Olaszországra jellemzőek [29]. A torlatokban elsősorban monacit, ritkábban xenotim található meg [30]. ...
As we enter the accelerated automation era and the so-called green revolution, the demand for rare earth elements (REE) grows. But what are these elements? Fifteen of them belong to the lanthanoids or lanthanides: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), as well as yttrium (Y) and scandium (Sc) from the transition metals. The main REE ore-minerals are bastnäsite, monazite, loparite and ion adsorption clays. The first three occur in carbonate or phosphate primary deposits, while the clay type of enrichments is related to sedimentation. There are many deposits around the globe, but few have been assessed so far. In recent years, the Chinese hegemony in extraction and resource/reserve evaluation seems to be breaking down. More and more countries are entering the rare earth elements market and conducting explorations. That is welcome news in respect of mutual raw material security, especially in the shadow of global phenomena such as the coronavirus, chip shortages, or monopoly situations. At the same time, Europe is trying to catch up and assess its raw material potential somewhat behind schedule. The following conclusions are made about the world's rare earth deposits and their potential. China, the most dominant player in the market, has vast carbonatite and hydrothermal mineralization. Mining of ion adsorption clays is significant too. The next big player in rare earth mining in Asia could be Vietnam, but Russia and India also have enormous reserves. Looking at North America, the USA is dominated by carbonatite deposits, such as Elk Creek, while in Canada, they are more of hydrothermal origin. In South America, Brazil is considered to have the third largest reserves of rare earths. Australia is a dominant player both in extraction and in terms of net mineral wealth. Africa's rare earth mining occurs in Madagascar from high-quality ion adsorption plants. The Republic of South Africa has one of the best monazite deposits in the world. Additional carbonatite deposits occur in the Democratic Republic of Congo, Tanzania, etc. The dependence of the European Union on raw materials and the achievement of the climate goals set in the Green Deal can be promoted by such crucial discoveries as the Swedish Per Greijer deposit this year. Europe's more well-explored raw material deposits are located in Scandinavia and Greenland, such as the carbonate Fen, Alnö, or the complex peralkaline Kvanefjeld. Many European Raw Material Alliance partners are exploring further opportunities across the continent.
... Lately, bauxite research has particularly focused on the potential for REE and associated critical metals (e.g. Radusinović et al., 2016;Papadopoulos et al., 2019;Radusinović and Papadopoulos, 2021;Mondillo et al., 2019;Mongelli et al., 2017;Tomašić et al., 2021;Yang et al., 2019;and others). Widely identified as regional markers of global events, bauxites occurred in distinctive periods in the geological history with warm and humid climates conjoined with tectonically controlled subaerial exposure of the carbonate platform (D'Argenio and Mindszenty, 1992;D'Argenio and Mindszenty, 1995). ...
Croatian bauxites are long known for their chemical and physical diversity arisen from their characteristic origin and emplacement within the area of the Adriatic–Dinaric carbonate platform (ADCP). They include eight horizons spanning the period between the Upper Triassic (Carnian) and the Miocene, formed on subaerially exposed platform paleoenvironments. The bauxite genesis is recorded in the bauxite geochemical composition as a unique signature of tectonostratigraphic evolution of the different parts of the Croatian Karst, including, for example, the forebulge unconformity typical for the Istrian area. In this work, an explanation of the typical patterns of bauxite formation is based on the construction of a discriminant function model (DFM) resulting from the compositional data (CoDa) analysis of bauxite geochemical data (major and trace elements). The model shows that the greatest part of the variation contained in the analyzed bauxite data (the first discriminant function, DF1) is associated with systematic alteration of geochemical composition in time, emphasizing characteristic decrease in clay component and gradual enrichment in heavy metals from oldest (Upper Triassic) to the youngest (Miocene) bauxites. In the general scheme, particular bauxite horizons represent standalone groups (Upper Triassic) while others form clusters showing increase and/or decrease of a particular set of elements signaling the changes in environmental conditions during the considered geological history of ADCP. Other discriminant functions (DF2 and DF3) also contribute to the all-inclusive distinction between the eight a priori defined bauxite groups discriminated by the characteristic set of geochemical variables where DF2 typically refers to the process of desilication, while DF3 to that of deferralitization.
... The LREE enrichment could be explained by the fact that allanite can contain Ce, La, or Nd, and monazite can contain Ce, La, Pr, Nd, or Sm (Wall, 2014). If compared to the other beach placers in the world that are reported to have high REE contents, both Erawan and Ombo have lower LREEs and HREEs compared to Odisha beach placer in India (Ghosal et al., 2020) and Atticocycladic beach placer in Greece (Papadopoulos et al., 2019) (Table 8). ...
... The Erawan and Ombo beach placer deposits in San Vicente, Palawan, are some of the few areas in the Philippines with high concentrations of rare earths (~600 ppm and ~ 300 ppm, respectively). Despite the elevated average REE concentrations for Erawan and Ombo beach placers, the limitation in current processing technology for allanite (Papadopoulos et al., 2019), the dominant REE-bearing mineral (Reyes et al., 1992), is a significant hindrance to the economic viability of these deposits. While the REEs in monazite can be extracted via flotation or a combination of gravity, magnetic and electrostatic processes, there is no available economic beneficiation process for allanite (Wall, 2014;Papadopoulos et al., 2019). ...
... Despite the elevated average REE concentrations for Erawan and Ombo beach placers, the limitation in current processing technology for allanite (Papadopoulos et al., 2019), the dominant REE-bearing mineral (Reyes et al., 1992), is a significant hindrance to the economic viability of these deposits. While the REEs in monazite can be extracted via flotation or a combination of gravity, magnetic and electrostatic processes, there is no available economic beneficiation process for allanite (Wall, 2014;Papadopoulos et al., 2019). Current policy also prohibits beach sand mining in the Philippines. ...
Rare earth elements (REEs) are now considered critical raw materials due to their economic importance and possible supply risk. To meet the future demand, explorations for REEs are currently active worldwide. In the Philippines, the REE potential of different mineral deposits was evaluated by examining the existing literature combined with new geochemical data. Elevated ∑REEs+Sc + Y levels are reported in Erawan beach (~600 ppm), Samar bauxites (~500 ppm), El Nido ion adsorption clay (~300 ppm), Ombo beach (~300 ppm), and Eastern Samar bauxites (~200 ppm). The similarities in the heavy REEs, Sc, and Y contents of Samar bauxite and other karstic bauxites in Spain, China, Turkey, and Montenegro suggest that it has the potential to be REE source in the Philippines. The comparability of Ce, Sm, Dy, Er, Tm, and Y contents of El Nido Ion Adsorption Clay (IAC) deposit to the cut-off grades of these REEs in southern China implies that this deposit could be an alternative source of these REEs. The Sc contents of Pulang Daga and Zambales Ni laterites (~70–80 ppm) higher than the cut-off grade for Ni laterite deposits in China and Australia suggest that mining Sc from these deposits could be profitable. The limitation in current processing technology makes the REE extraction in allanite-rich Erawan and Ombo beaches economically unviable under the current economic conditions. Developing bauxite, IAC, and Ni laterite deposits into REE mines could face challenges like high electricity costs and government environmental policies. The low REE contents of other Philippine deposits such as Leyte phosphogypsum, San Vicente granite, Isabela coal, Didipio alkaline rocks, La Union beach placer, Panganiban and Mt. Labo skarns, Santo Tomas II porphyry Cu, Paracale epithermal Au, Ilocos Norte feldspar, and Rapu-Rapu VMS makes the REE beneficiation for these deposits impractical for now. Future developments in extractive REE metallurgy may transform these presently uneconomic REE resources of the Philippines to be viable REE ores for the domestic and global market.
... 2001). Τα κύρια ορυκτά που εντοπίζονται στο βαρύ κλάσμα των άμμων αυτής της παράκτιας ζώνης είναι η αμφίβολος (Mg-κεροστίλβη και παργασίτης), ο μαγνητίτης, ο τιτανίτης, ο αλλανίτης και το επίδοτο, ο απατίτης και ο αιματίτης, ενώ σε μικρότερο ποσοστό συμμετέχουν τα ορυκτά ζιρκόνιο, μοναζίτης, ιλμενίτης, ρουτίλιο, τσεραλίτης (cheralite), ξενότιμο, βαρύτης, καθώς και διάφορα σουλφίδια (Tzifas et al. 2019, Stouraiti et al. 2020. αλλανίτης είναι ο κύριος φορέας των σπάνιων γαιών στη ζώνη αυτή, και συμμετέχει στο βαρύ κλάσμα σε ποσοστό 3%. ...
... αλλανίτης είναι ο κύριος φορέας των σπάνιων γαιών στη ζώνη αυτή, και συμμετέχει στο βαρύ κλάσμα σε ποσοστό 3%. Επίσης, ο αλλανίτης αποτελεί το 2 έως 10%, στο μαγνητικό κλάσμα της άμμου και το 12 έως 20% στο μη μαγνητικό (Tzifas et al. 2019. ...
... ι περιεκτικότητες του αλλανίτη σε σπάνιες γαίες στην παράκτια ζώνη μεταξύ ουτρών Ελευθερών και έας εράμου είναι συνολικά περίπου 13%, με το μεγαλύτερο ποσοστό να αποτελούν οι ελαφριές σπάνιες γαίες και συγκεκριμένα το λανθάνιο (La), το δημήτριο (Ce) και το νεοδύμιο (Nd) που κυμαίνονται μεταξύ 6 και 13% (Tzifas et al. 2019, Stouraiti et al. 2020. αλλανίτης επίσης περιέχει έως 0,12% Th, ενώ αξιοσημείωτες είναι και οι περιεκτικότητες σε κρίσιμα μέταλλα όπως V έως 399 g/t, Ga έως 458 g/t και Sc έως 94 g/t (Tzifas et al. 2019, Stouraiti et al. 2020. ...
https://repository.kallipos.gr/handle/11419/8353?&locale=el
Το βιβλίο αυτό αναφέρεται στην καταγραφή των σημαντικότερων μεταλλοφόρων κοιτασμάτων της Ελλάδας και στις συνθήκες γένεσής τους σε σχέση με τη γεωτεκτονική εξέλιξη των Ελληνίδων. Έμφαση δίνεται στη γεωλογία, στην τεκτονική, στα πετρώματα ξενιστές και στην ορυκτολογική και γεωχημική σύσταση των κοιτασμάτων αυτών. Τα κεφάλαια του παρόντος βιβλίου αναφέρονται στη σύντομη ιστορική αναδρομή της μεταλλευτικής δραστηριότητας στην Ελλάδα, από τα προϊστορικά χρόνια έως σήμερα, στη γεωτεκτονική εξέλιξη και μεταλλογένεση, καθώς και στην ταξινόμηση των ελληνικών κοιτασμάτων στις διαφορετικές μεταλλογενετικές επαρχίες. Περιγράφονται τα ορθομαγματικά κοιτάσματα Cr σε οφιολιθικά συμπλέγματα, τα ηφαιστειογενή κοιτάσματα συμπαγών σουλφιδίων και τα μεταμορφωμένα κοιτάσματα Mn, όλα Μεσοζωικής ηλικίας. Επίσης, παρουσιάζονται οι μαγματικές-υδροθερμικές μεταλλοφορίες που συνδέονται με τον μαγματισμό του Καινοζωικού και που εντοπίζονται κυρίως στα δύο σημαντικά μεταμορφικά συμπλέγματα της Ελλάδας, της Ροδόπης και Σερβομακεδονικής στα βόρεια και της Αττικοκυκλαδικής στα νότια. Αυτές οι μεταλλοφορίες περιλαμβάνουν τα κοιτάσματα που φιλοξενούνται σε μαγματικές διεισδύσεις, τα κοιτάσματα τύπου skarn, τα κοιτάσματα από αντικατάσταση ανθρακικών πετρωμάτων και τα κοιτάσματα πορφυριτικού και επιθερμικού τύπου. Αναπτύσσονται επίσης οι πολυμεταλλικές φλέβες του Καινοζωικού σε μεταμορφωμένα πετρώματα, τα κοιτάσματα Fe, Mn, Zn από οξείδωση θειούχων μεταλλοφοριών, τα λατεριτικά κοιτάσματα Fe-Ni, τα κοιτάσματα βωξίτη με αλουμίνιο, τα προσχωματικά κοιτάσματα Au, Pt και REE, καθώς και τα σύγχρονα μεταλλοφόρα πεδία στο ενεργό ηφαιστειακό τόξο του Νοτίου Αιγαίου και στην Κεντρική και Βόρεια Ελλάδα. Στο τέλος του βιβλίου γίνεται μία ανασκόπηση σχετικά με την παρουσία των σπάνιων και κρίσιμων μετάλλων στα κοιτάσματα της Ελλάδας, ενώ στο τελευταίο κεφάλαιο δίνονται λεπτομερή γεωλογικά και κοιτασματολογικά στοιχεία δύο σημαντικών μεταλλογενετικών περιοχών της Νοτιοανατολικής Ευρώπης, δηλαδή της ΒΑ Χαλκιδικής και του Λαυρίου
... The area was also investigated in the frame of the EuRare project (2013-2015) that focused on mapping and characterization of REE deposits in Europe [16]. Recently, natural radioactivity measurements and detailed geochemical analyses of enriched sand fractions were conducted in order to determine the source and the chemical character of the REE-rich minerals [16][17][18][19][20][21]. ...
... Beach placers of Kavala district are considered to be one of the most promising REE sources in Greece, since they demonstrate the most significant enrichment in ΣREE + Y [19,20] compared to the other REE occurrences in Greece. The purpose of the present work is to determine the nature of the REE-bearing minerals in the black sands from six locations between the Strymonikos Gulf and Eleftheres Bay, of the Kavala district in Northern Greece ( Figure 1). ...
... The REE-bearing minerals in the black sands of the Kavala area are dominated by allanite-(Ce), REE-rich epidote, monazite-(Ce), monazite-(La) and thorite. Zircon and titanite have been reported in previous studies [16,19] as light REE (LREE) and heavy REE (HREE) carriers, respectively, based on the sensitive analytical method laser-ablation inductively coupled plasma mass spectrometry (LA-ICPMS), but the concentrations of the REE were under the detection limits of the analytical method (SEM-EDS) used in the present study. Zircon from the Kavala area, apart from Zr, contains minor amounts of Hf, U and Th, whereas V and Nb occur in traces in titanite. ...
The coastal area of the Kavala district, Northern Greece, is characterized by minerals enriched in rare earth elements (REE). The present study focuses on the mineralogy of the black sands from six different locations and the comprehensive mineral chemistry of the REE-bearing minerals, allanite-(Ce), epidote, monazite, thorite, zircon and titanite. Allanite-(Ce) is the most important carrier of light REE (LREE) in the studied black sands, reaching up to 23.24 wt % ΣREE. The crystal chemistry of allanite-(Ce) transitions into ferriallanite-(Ce), due to the significant involvement of Fe 3+. High resolution backscattered electron (BSE) images were used to identify zoning that corresponds to variations in REE, Th and U. These modifications follow the exchange scheme: (Ca + (Fe 3+ , Al))−1(LREE, Y, Th, U + (Fe 2+ , Mg, Mn))+1. Epidotes may also contain up to 0.5 REE 3+ apfu. Monazite and thorite are found as inclusions in allanite-(Ce) and are enriched in Ce, La and Nd, together with Th and U. Some zircons are enriched in Hf, while some titanites host Nb and V.
... The major types of RE deposits are carbonatites, alkaline igneous rocks, pegmatites, iron oxide copper-gold (IOCG) deposits, placers (alluvial and beach placers), laterites and ion adsorption clays [3]. Among these deposit types, beach placers have attracted more attention by the exploration community due to the diversified economic interest resulted by the wide-ranging provenance control from one deposit to another [4]. Therefore, beach placers are an economically important RE deposit type, if its provenance is associated with a REE-bearing source rock. ...
... Beach placers contain common economic minerals like ilmenite, rutile and magnetite along with REE-bearing minerals, such as monazite, xenotime and zircon. However, beach placers do have actinides, such as thorium (Th) and uranium (U) resulting the downstream processing of REEs difficult and problematic [4]. ...
... However, more detailed close grid studies must be 14.0 -6474.0 [4] carried out in order to assess the actual potential of REEs in the beach placers along the southwest coast of Sri Lanka. ...
—In the recent few years, rare earth elements
(REEs) were considered as critical metals with strategic
importance due to their high usage in modern technology and
green energy applications. Currently, with the unexpected
increase of rare earth element (REE) demand and China’s
market dominance, many REE processing projects are being
launched or revived. In this regard, the present work is focused
on assessing the REE potential in the beach placers along the
southwest coastline in Sri Lanka. The collected 36 beach sand
samples from the mean sea-level in the southwest coast during
both southwestern and northeastern monsoons were subjected
to both elemental and mineralogical analyses. Based on the
findings, Galle, Ginthota, Wadduwa, and Thelwatta areas were
found with significant contents of REEs ranging from 32.8-
1,359.1 mg/kg. Moreover, the results suggest that REE-bearing
heavy minerals are heavily concentrated in the beach face due
to stronger oceanic currents generated by the strong winds of
the southwestern monsoon along with the increased sediment
supply by inland rivers. The findings in this study would provide
insights for future REE prospecting studies, which is helpful in
unraveling the hidden potential of REE resources in Sri Lankan
beach placer deposits.
... There is a particular focus from the scientific community as far as REE's deposits. In the case of beach placer deposits, there are numerous studies referring to areas of economic value due to their REE and other critical elements content [1]. Particularly in Greece there are several publications studying the REE and natural radioactivity content in beach placer deposits [1]. ...
... In the case of beach placer deposits, there are numerous studies referring to areas of economic value due to their REE and other critical elements content [1]. Particularly in Greece there are several publications studying the REE and natural radioactivity content in beach placer deposits [1]. Coastal sands from Aggelochori area close to Thessaloniki (N.-Greece) have been studied by Filippidis et al. 1997 [2] but there are no studies of source formation of the beach placers, up to now. ...
Beach sands from Aggelochori coast line are investigated for their geochemistry and REE content, mineralogy and their provenance. These fluvial sands bear heavy minerals enriched horizons (containing minerals such as magnetite, zircon, ilmenite, hematite, rutile and titanite) that can be distinguished due to their black color and are formed usually due to the action of sea waves that deposit the heavy minerals and remove the lighter ones. After a suitable processing (washing, sieving, drying and magnetic separation) of the samples, the mineral constituents and their presence (wt.%) were estimated by XRD. Among the samples, the one being simultaneously the more fine grained and the more zircon-enriched (as suggested by XRPD data and optical microscopy analysis) has been selected for further geochemical analyses. The major and trace elements contents were compared to previously studied REE enriched beach sands from Kavala and Sithonia. Beach sands from Aggelochori area appear to have relatively low REE contents. Considering the provenance of these sediments, we suggest that these sands, are a product of the erosion of multi-sources, including the near-by Monopigado granite, as well as metamorphic rocks, as indicated by the presence of rutile and both ilmenite and magnetite in some samples. Therefore, there are indications of a complex flow pattern that existed at the paleo-catchment area of the deposition.
... In a dynamic system, the alterability of allanite can promote the higher mobilization of REE and radionuclides (Ichimura et al., 2020), as in the first stage of supergene alteration (Harlavan and Erel, 2002). In the absence of depositional ligands as fluorine and phosphate (in the sense of Migdisov et al., 2016), allanite can be less reactive and explain its preservation in placer-type deposit (Papadopoulos et al., 2019). ...
Les éléments de terres rares (REE) sont autant de précieux traceurs géochimiques que des métaux critiques indispensables au fonctionnement des sociétés modernes. Comprendre les conditions et les mécanismes de leurs transferts dans la croûte continentale est un enjeu majeur de ce siècle. Malgré de forts intérêts géochimiques et socio-économiques, beaucoup de questions demeurent quant à leur redistribution et leur fractionnement au cours des interactions fluide-roche. Ces lacunes de compréhension proviennent notamment du manque de données thermochimiques sur la stabilité de certains minéraux clés et de la difficulté à contraindre l’ensemble des paramètres intervenant en milieu naturel dynamique. L’objectif de cette thèse est d'évaluer les mécanismes d’altération, ainsi que la redistribution et le fractionnement des REE en conditions hydrothermales et supergènes. Ce travail combine l’expérimentation et l’étude d’échantillons naturels au travers d’une approche multidisciplinaire au travers d’investigations pétrologiques, minéralogiques et géochimiques.Une première série d’expériences en système fermé (batch reactor) a été menée sur des cristaux d’allanite à 200°C en présence de carbonates et de différents ligands. Dans les fluides dopés en fluorures et en phosphates, l’allanite montre une forte réactivité par des mécanismes de dissolution-précipitation et par la formation de couronne réactionnelle, dont l’assemblage minéralogique reproduit de nombreuses descriptions en milieu naturel. Le remplacement partiel par des phases de REE (bastnäsite, parisite, synchysite ou monazite) agit comme un catalyseur sur les réactions d’altération. Les LREE sont alors piégées dans ces minéraux secondaires, tandis que les fluides fractionnent préférentiellement les HREE en comparaison des phases solides. L'augmentation du pH accroît la cinétique, l’intensité des réactions, ainsi que la concentration des REE, du Th et de l’U dans les fluides.L’approche expérimentale s’est étendue à l’altération en milieu dynamique (fluid-through) sous pression à 180 °C d’un système granitique assez riche en allanite, apatite et titanite (Lauzière, Alpes françaises). Pour un fluide de composition H2O + CO2, l’allanite ne montre pas d’évidence d’altération, au contraire de la titanite, de l’albite, de l’apatite et de la biotite. La mise en solution d’ions phosphates par dissolution de l’apatite entraîne la précipitation de phosphates de REE en remplacement de la titanite. L’altération s’initie à partir des surfaces réactionnelles exposées dans les chemins de circulation du fluide (fractures) et se propage en fonction des paramètres cristallographiques du minéral (clivages).La distribution et le fractionnement des REE lors de l’altération supergène ont été évalués dans un profil latéritique (Madagascar) par extraction séquentielle. La procédure a été contrôlée par application sur des phases minéralogiques synthétiques dopées au cérium représentatives de l’échantillon naturel. L’utilisation d'hydroxylammonium hydrochloride, solvant couramment utilisé lors de ces protocoles, montre d'importants défauts de sélectivité. Alors que certaines latérites sont reconnues pour leur enrichissement en REE adsorbées à la surface des argiles, les HREE et le Ce sont ici majoritairement associés aux oxyhydroxydes de Fe (et de Mn) dans l’horizon B enrichi en REE. Le budget des LREE (sauf Ce) dans l’horizon B et de l’ensemble des REE dans les horizons A et C est principalement contrôlé par les phosphates authigéniques (groupes du rhabdophane et de l’alunite-jarosite).Les résultats de ces travaux apportent de nouvelles données pour comprendre les processus généraux de transferts et de mobilité des REE, ainsi que pour contraindre les modèles pétrogénétiques de formation des gisements de REE.
... A significant positive correlation between Al 2 O 3 and K 2 O for the Riachuelos (r = 0.81) and Palma Sola (r = 0.87) beach sediments indicates that a considerable proportion of K is associated with fine-grained sediments or phyllosilicates (Etemad-Saeed et al. 2015;Greggio et al. 2018;Udayanapillai et al. 2020). Al 2 O 3 against TiO 2 reveals a negative correlation for the Riachuelos (r = − 0.36, n = 15) and Palma Sola (r = − 0.01, n = 20) beach sediments, indicating that TiO 2 is not associated with aluminous clays or its association with titano-magnetite and ilmenite (Nagarajan et al. 2015(Nagarajan et al. , 2017Papadopoulos et al. 2019). Similarly, a weak correlation between Al 2 O 3 and P 2 O 5 for the Riachuelos (r = − 0.70, n = 15) and Palma Sola (r = 0.13, n = 20) beach sediments suggests P 2 O 5 content is associated with detrital minerals, probably apatite (Fig. 4a). ...
Zircons are abundant in the beach sediments. In this study, surface microtexture, mineralogy, bulk sediment geochemistry, trace element composition and U–Pb isotopic geochronology of detrital zircons collected from the Riachuelos and Palma Sola beach areas, southwestern Gulf of Mexico were performed to infer the sediment provenance and palaeoenvironment. The zircon microtexture was categorized as mechanically- and/or chemically-induced features. The weathering index values for the Riachuelos (~ 72 – 77) and Palma Sola (~ 71–74) beach sediments indicated moderate weathering of both of the two source areas. The major and trace element data of bulk sediments suggested passive margin settings for the two areas. The trace elemental ratios and chondrite-normalized rare earth element (REE) patterns of bulk sediments revealed that the sediments were likely sourced by felsic and intermediate igneous rocks. And the zircon Th/U ratios (mostly more than 0.2) and zircon REE patterns (with negative Eu and positive Ce anomalies) suggested a magmatic origin for both of the beach sediments from these two areas. Two distinct zircon age peaks respectively belonging to the Paleozoic and the Cenozoic were identified both in the Riachuelos and Palma Sola beach sediments. Zircon geochronology comparison research between the Riachuelos–Palma Sola beach sediments and potential source areas in SW Gulf of Mexico revealed that the source terrane supplied the Paleozoic zircons of this study was identified as the Mesa Central Province (MCP), and the Cenozoic zircons were transported from the nearby Eastern Alkaline Province (EAP). Moreover, although the Precambrian zircons were very few in the studied sediments, their geochronology and geochemistry results still could infer that they were contributed by the source terranes of Grenvillian igneous suites in the Oaxaca and the Chiapas Massif Complexes.
... India, endowed with a coastline of over 7000 km, contains some of the richest shoreline placer deposits in the world (Nayak et al., 2012;Kumar et al., 2019). These deposits formed as a result of differential mechanical weathering of parental rocks in the hinterland under tropical to sub-tropical climate as wind-and rivertransported altered products that were deposited, or redeposited along the coast (Choudary et al., 2010;Kumar et al., 2010;Papadopoulos et al., 2019;Akon, 2019). However, the dimensions and depositional patterns of the coastal placers are controlled by geomorphology, winds and wave action (Dill and Ludwig, 2008;Rao et al., 2008;Nair et al., 2009;Kirkpatrick et al., 2019). ...
... The beach sands are the storehouse for many heavy minerals. They have a diverse economic interest as a result of a wide-ranging provenance control from one deposit to another (Jaireth et al., 2014;Papadopoulos et al., 2019). India has almost 35 percent of the world's total beach sand mineral deposits. ...
Exploration for strategic placer mineral deposits in a fluctuating shoreline: Depositional environment and mineralogical characterization of the NE Odisha coast placers, India
Rambabu Singh a,b, A.S. Venkatesh b,*, Ch. Sudhakar c, Satya N. Sethy b,d, K. Prasad Babu b,e
a Central Mine Planning and Design Institute Limited, Bilaspur, India b Department of Applied Geology, Indian Institute of Technology, (Indian School of Mines), Dhanbad, India c Atomic Minerals Directorate for Exploration and Research, Hyderabad, India d Geological Survey of India, Eastern Region, Kolkata, 700091, India e Department of Chemical Engineering, CBIT, Hyderabad, India
Highlights
•
Characterisation of different radioactive and non-radioactive mineral potential zones.
•
The down core variation of heavy mineral assemblages of unexplored deposits.
•
The implicative depositional environment in a fluctuating shoreline.
•
The LDA analysis and CM plot indicate graded suspension without any rolling conditions.
Abstract
Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.
Graphical abstract
Highlights
•
Characterisation of different radioactive and non-radioactive mineral potential zones.
•
The down core variation of heavy mineral assemblages of unexplored deposits.
•
The implicative depositional environment in a fluctuating shoreline.
•
The LDA analysis and CM plot indicate graded suspension without any rolling conditions.
Abstract
Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.
Graphical abstract
Highlights
•
Characterisation of different radioactive and non-radioactive mineral potential zones.
•
The down core variation of heavy mineral assemblages of unexplored deposits.
•
The implicative depositional environment in a fluctuating shoreline.
•
The LDA analysis and CM plot indicate graded suspension without any rolling conditions.
Abstract
Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.
Graphical abstract
Abstract
Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.
Graphical abstract
Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.
Graphical Abstract
