Special Issue "Rare Earth Deposits and Challenges of World REE Demand for High-Tech and Green-Tech at the Beginning of the 3rd Millennium"

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: 30 June 2019

Special Issue Editors

Guest Editor
Dr. Jindřich Kynický

Department of Geology and Pedology, Mendel University in Brno, 61300 Brno, Czech Republic
Website | E-Mail
Interests: economic geology; formation of critical metals deposits; rare earth elements; carbonatites; alkaline rocks; economic mining; fair play mining and sustainability in developing countries; REE mineralization and economic deposits of Mongolia, Siberia, Africa
Guest Editor
Dr. Martin Smith

School of Environment and Technology, University of Brighton, Lewes Road, Brighton, UK
Website | E-Mail
Interests: rare earth elements; REE deposits; REE mineralization; carbonatites; alkaline rocks; metasomatic, hydrothermal and late stage magmatic processes; hydrogeology
Guest Editor
Dr. Stefano Salvi

Géosciences Environnement Toulouse (GET), University of Toulouse, 31400 Toulouse, France
Website | E-Mail
Interests: economic geology; formation of high-tech metal deposits; alkaline rocks; hydrothermal transport of REE and HFSE; fluid inclusions; orogenic gold deposits

Special Issue Information

Dear Colleagues,

The rapid development of environmentally-friendly and other innovative technologies in the past century have greatly increased the demand for rare earth elements (REE) and, most recently, neodymium (Nd), dysprosium (Dy), niobium (Nb) and other critical materials in particular. The need for new sources of these materials has been amplified by the current situation in their supply markets, with a growing public concern about unlawful, unethical (e.g., “conflict coltan” in the Democratic Republic of the Congo) or environmentally harmful extraction (REEs sourced from the “South China clays”) of some rare-metal resources. Critical materials are, and will likely remain, indispensable for the implementation and further advancement of low-carbon energy and transportation technologies, such as wind farms and electric vehicles. An increased interest in these resources in the exploration, government and public sectors, stimulated by the need to secure new sources of critical and rare materials resilient to politically driven fluctuations in the global supply market, requires a much better understanding of critical-metal deposits than that which is currently available.

Rare metals, such as REE are initially concentrated early in the evolution of carbonatitic and other REE rich magma to form primary mineralization. The behavior of these metals during metamorphism, deformation and metasomatic reworking is one significant aspect of carbonatite and other REE-rich rocks’ petrogenesis that has direct implications for the economic potential of these rocks, but has not been studied in much detail.

Rare Earth Deposits and challenges of world REE demand for High-Tech and Green-Tech at the beginning of 3rd millennium gives us the chance to recognize expertise in mineralogy, petrology and geochemistry of REE deposits.

The proposed “REE deposits issue” will cover the geology and exploration of the major REE deposit types and their tectonic settings, as well as address the key economic and political issues related to REE mining, extraction problems in the case of individual deposit and mineralization types, economic mineral associations and recent versus future mining and mineral processing development, challenge of silicate REE ores, emergence of REE as a distinct resource type and the evolution of society's perception of these commodities over the past 100 years.

We are inviting you to contribute a paper on this subject to the proposed Special Issue. This Special Issue will contribute to a better understanding of REE deposits and REE mineralization that may be key for future exploration. It will also impact on the development of socially and environmentally responsible mining in developing countries where the most REE deposits exist.

We look forward to hearing from you.

Best wishes,

Dr. Jindřich Kynický
Dr. Martin Smith
Dr. Stefano Salvi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Rare earth elements
  • REE deposits
  • REE ores
  • Primary REE mineralization
  • Metasomatic reworking
  • REE dissolution and reprecipitation
  • Carbonatites
  • Alkaline rocks
  • Economic potential
  • Economic mining
  • REE processing

Published Papers (3 papers)

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Research

Open AccessArticle
Non-Metamict Aeschynite-(Y), Polycrase-(Y), and Samarskite-(Y) in NYF Pegmatites from Arvogno, Vigezzo Valley (Central Alps, Italy)
Minerals 2019, 9(5), 313; https://doi.org/10.3390/min9050313
Received: 19 April 2019 / Revised: 15 May 2019 / Accepted: 16 May 2019 / Published: 21 May 2019
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Abstract
At Arvogno, Vigezzo valley in the Central Alps, Italy, pegmatite dikes are unique in the scenario of a tertiary alpine pegmatite field because they show marked geochemical and mineralogical niobium–yttrium–fluorine features. These pegmatites contain AB2O6 aeschynite group minerals and ABX [...] Read more.
At Arvogno, Vigezzo valley in the Central Alps, Italy, pegmatite dikes are unique in the scenario of a tertiary alpine pegmatite field because they show marked geochemical and mineralogical niobium–yttrium–fluorine features. These pegmatites contain AB2O6 aeschynite group minerals and ABX2O8 euxenite group minerals as typical accessory minerals including aeschynite-(Y), polycrase-(Y), and samarskite-(Y). They are associated with additional typical minerals such as fluorite, Y-dominant silicates, and xenotime-(Y). The Y–Nb–Ti–Ta AB2O6 and ABX2O8 oxides at the Arvogno pegmatites did not exhibit any textural and compositional features of oxidation or weathering. They are characterized by low self-radiation-induced structural damage, leading to the acquisition of unit-cell data for aeschynite-(Y), polycrase-(Y), and samarskite-(Y) by single-crystal X-ray diffraction. Aeschynite-(Y) and polycrase-(Y) crystals allowed for both to provide space groups whereas samarskite-(Y) was the first crystal from pegmatites for which cell-data were obtained at room temperature but did not allow for the accurate determination of the space group. According to the chemical compositions defined by Ti-dominant content at the B-site, the cell parameters, respectively, corresponded to polycrase-(Y), aeschynite-(Y), and the monoclinic cell of samarskite-(Y). Emplacement of Alpine pegmatites can be related to the progressive regional metamorphic rejuvenation from east to west in the Central Alps, considering the progressive cooling of the thermal Lepontine Barrovian metamorphic dome. Previous studies considered magmatic pulses that led to emplace the pegmatite field in the Central Alps. As an example, the pegmatites that intruded the Bergell massif were aged at 28–25 millions of years or younger, around 20–22 m.y. Full article
Open AccessFeature PaperArticle
Volcanic-Derived Placers as a Potential Resource of Rare Earth Elements: The Aksu Diamas Case Study, Turkey
Minerals 2019, 9(4), 208; https://doi.org/10.3390/min9040208
Received: 15 February 2019 / Revised: 22 March 2019 / Accepted: 26 March 2019 / Published: 30 March 2019
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Abstract
Rare earth elements (REE) are essential raw materials used in modern technology. Current production of REE is dominated by hard-rock mining, particularly in China, which typically requires high energy input. In order to expand the resource base of the REE, it is important [...] Read more.
Rare earth elements (REE) are essential raw materials used in modern technology. Current production of REE is dominated by hard-rock mining, particularly in China, which typically requires high energy input. In order to expand the resource base of the REE, it is important to determine what alternative sources exist. REE placers have been known for many years, and require less energy than mining of hard rock, but the REE ore minerals are typically derived from eroded granitic rocks and are commonly radioactive. Other types of REE placers, such as those derived from volcanic activity, are rare. The Aksu Diamas heavy mineral placer in Turkey has been assessed for potential REE extraction as a by-product of magnetite production, but its genesis was not previously well understood. REE at Aksu Diamas are hosted in an array of mineral phases, including apatite, chevkinite group minerals (CGM), monazite, allanite and britholite, which are concentrated in lenses and channels in unconsolidated Quaternary sands. Fingerprinting of pyroxene, CGM, magnetite and zircon have identified the source of the placer as the nearby Gölcük alkaline volcanic complex, which has a history of eruption throughout the Plio-Quaternary. Heavy minerals were eroded from tephra and reworked into basinal sediments. This type of deposit may represent a potential resource of REE in other areas of alkaline volcanism. Full article
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Open AccessArticle
Geology and Mineralogy of Rare Earth Elements Deposits and Occurrences in Finland
Minerals 2018, 8(8), 356; https://doi.org/10.3390/min8080356
Received: 3 June 2018 / Revised: 3 July 2018 / Accepted: 5 July 2018 / Published: 18 August 2018
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Abstract
Rare earth elements (REE) have critical importance in the manufacturing of many electronic products in the high-tech and green-tech industries. Currently, mining and processing of REE is strongly concentrated in China. A substantial growth in global exploration for REE deposits has taken place [...] Read more.
Rare earth elements (REE) have critical importance in the manufacturing of many electronic products in the high-tech and green-tech industries. Currently, mining and processing of REE is strongly concentrated in China. A substantial growth in global exploration for REE deposits has taken place in the recent years and has resulted in considerable advances in defining new resources. This study provides an overview of the mineralogical and petrological peculiarities of the most important REE prospects and metallogeny of REE in Finland. There is a particularly good potential for future discoveries of carbonatite hosted REE deposits in the Paleozoic Sokli carbonatite complex, as well as in the Paleoproterozoic Korsnäs and Kortejärvi Laivajoki areas. This review also provides information about the highest known REE concentration in the alkaline intrusions of Finland in the Tana Belt and other alkaline rock hosted occurrences (e.g., Otanmäki and Katajakangas). Significant REE enrichments in hydrothermal alteration zones are also known in the Kuusamo Belt (Uuniniemi and Honkilehto), and occurrences of REE-rich mineralisation are also present in granite pegmatite bodies and greisens in central and southern Finland (Kovela monazite granite and the Rapakivi Granite batholith at Vyborg, respectively). REE minerals in all of the localities listed above were identified and analyzed by scanning electron microscopy (SEM) and electron microprobes (EMPs). In localities of northern and central Finland, both primary rock forming and epigenetic-hydrothermal REE minerals were found, namely phosphates (monazite-Ce, xenotime-Y), fluorcarbonates (bastnäsite-Ce, synchysite), and hydrated carbonates (ancylite-Ce), hydrated aluminium silicates (allanite-Ce, Fe-allanite, cerite, chevkinite), oxides (fergusonite, euxenite) and U-Pb rich minerals. The chondrite normalized REE concentrations, the La/Nd ratios and the REE vs. major element contents in several types of REE bearing minerals from prospects in Finland can be used to identify and define variable REE fractionation processes (carbonatites), as well as to discriminate deposits of different origins. Full article
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Graphical abstract

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