A rare-earth mineral contains one or more rare-earth elements as major metal constituents. Rare-earth minerals are usually found in association with alkaline to peralkaline igneous complexes in pegmatites. This would be associated with alkaline magmas or with carbonatite intrusives. Perovskite mineral phases are common hosts to rare-earth elements within the alkaline complexes. Minerals are the solid composer of inorganic substances. [1] They are formed through the atomic movement of fluid which can be derived from evaporation, pressure or any physical change. [2] They are mostly determined through their atomic weight. [3] The minerals that are known as 'rare' earth minerals are considered rare due to their unique geochemical makeup and properties. [4] These substances are not normally found in mining affiliated clusters. [4] Thus an indication of these minerals being short in supply and allocated their title as 'rare' earth minerals. [4] Many of our rare-earth minerals include rare-earth elements which thus hold the same significant purpose of rare-earth minerals. [5] Earth's rare minerals have a wide range of purposes, including defense technologies and day-to-day uses. [6] This would be associated with alkaline magmas or with carbonatite intrusives. Perovskite mineral phases are common hosts to rare-earth elements within the alkaline complexes. Mantle-derived carbonate melts are also carriers of the rare earths. Hydrothermal deposits associated with alkaline magmatism contain a variety of rare-earth minerals. Rare-earth minerals are usually found in association with alkaline to peralkaline igneous complexes in pegmatites.
The following includes the relatively common hydrothermal rare-earth minerals and minerals that often contain significant rare-earth substitution:
This particular group of minerals contains elements that are considered rare in our planet's makeup. [9] To be classified as a rare earth mineral, a thorough examination of the element contained within it is mandatory. [9] If an element can be classified as a rare-earth element, it is more likely to be classified as a rare earth mineral. This information can be valuable in various settings, such as geological surveys and mineral resource assessments. [10] A rare earth element is categorized into sixteen metallic elements. [10] There are over 160 rare earth minerals and only four of these minerals are mined. [11] Most rare earth minerals occur in primary and secondary deposits. [12]
Primary deposits contain hydrothermal and igneous processes while secondary deposits are sedimentary and weathering processes. [13] In the case of primary deposits, the minerals and metals are derived from a specific area, where the elements come together to form the deposit. [14] This location is also where the mineral is produced. [14] Derived elements move to a different location within secondary deposits where they undergo metamorphic or sedimentary processes, resulting in the formation of minerals. [15] Mining extractions can benefit from the mineral processing of elemental deposits. [16] Various methods, such as leaching and hydrothermal processes, can be employed to extract minerals. [17] Both primary and secondary deposits yield elements and minerals for mining purposes. [17] There are only four rare-earth minerals that are found in deposits that go through certain processes and require mining. [18]
Bastnäsite is a carbonate mineral, that is primarily mined for its many purposes. [19] Magnets made of bastnasite are used to create speakers, microphones, communication devices, and many other modern gadgets. [20] This mineral is rare because it contains a large number of rare elements. [21] This mineral can be classified as semi-soluble salt due to its limited solubility in water and capacity to form ionic bonds. [21] Bastnäsite deposits are found in China and the USA. [21]
Laterite is considered to be a soil type which holds a significant amount of aluminium and iron. [24] This soil type can form into clay, which holds many minerals within it. [24] The weathering of rocks under leaching and oxidation conditions results in the formation of this mineral soil, which simulates clay. [24] The minerals within this soil are goethite, lepidocrocite, and hematite. [24] In recognition of the weathering process that these minerals require, they are classified as rare earth minerals. [25] In addition to these rare minerals other elements are contained within this soil like substance such as iron and nickel. [26] Thus having a red colour like soil through the oxidation of these minerals. [26] Basalt is the source of laterite, which is a material that contains aluminum. [25] Its high aluminum content is the reason it is mined. [26] This clay-like dirt also makes a stable basis for construction since it solidifies into rock when exposed to air. [26] However, the low fertility of this soil makes it unsuitable for agricultural use. [26]
Monazite is a waxy mineral that is formed through the crystallization of igneous rocks and the metamorphism of clastic sedimentary rocks. [27] This mineral is typically mined in placer deposits, with gold commonly found as a byproduct. [27] The rare earth element neodymium is found in monazite, making it a rare mineral. [27] Moreover, monazite contains many other rare metals such as cerium, lanthanum, praseodymium, and samarium, making it a critical source of renewable energy. [28] Recycled magnets can also be derived from these minerals due to the metals they contain. [27] Monazite sand and deposits for mining are found in India, Brazil, and Australia. [29]
Loparite is a mineral that contains three rare elements: titanium, niobium, and tantalum. [30] This is why it is often mined, as it is considered a rare-earth mineral. [30] The deposits for loparite can be found in Russia and Paraguay, although it is also present in other countries such as Canada, Norway, Greenland, and Brazil. [31] However, Russia remains the primary source for mining this mineral. [31] The significance of loparite lies in its unique properties, which make it useful for conductivity, aircraft assembly, and as a radioactive tracer. [30]
Kyawthuite is an incredibly rare earth mineral due to its unique formation process. [32] Unlike other minerals, it is created from a pegmatite deposit within an igneous rock. [33] Its deep red-brown colour and high density come from the crystal assemblages within it. [34] Unfortunately, its occurrence is very limited and the necessary pressure for formation is uncommon, making it quite scarce. The mineral contains lead, thallium, and oxygen that have undergone oxidation and is also composed of the rare metals bismuth and antimony. [33] Interestingly, the mineral is named after Dr. Kyaw Thu, a former geologist at the University of Yangon who discovered it. [33] It is found in the region of Myanmar Mogok. [35]
Further reading
Europium is a chemical element; it has symbol Eu and atomic number 63. Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. Europium usually assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on Earth.
Ore is natural rock or sediment that contains one or more valuable minerals concentrated above background levels, typically containing metals, that can be mined, treated and sold at a profit. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral.
Samarium is a chemical element; it has symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide.
Zircon is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.
The rare-earth elements (REE), also called the rare-earth metals or rare earths or, in context, rare-earth oxides, and sometimes the lanthanides, are a set of 17 nearly indistinguishable lustrous silvery-white soft heavy metals. Compounds containing rare earths have diverse applications in electrical and electronic components, lasers, glass, magnetic materials, and industrial processes.
Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm3. There are five different most common species of monazite, depending on the relative amounts of the rare earth elements in the mineral:
The mineral bastnäsite (or bastnaesite) is one of a family of three carbonate-fluoride minerals, which includes bastnäsite-(Ce) with a formula of (Ce, La)CO3F, bastnäsite-(La) with a formula of (La, Ce)CO3F, and bastnäsite-(Y) with a formula of (Y, Ce)CO3F. Some of the bastnäsites contain OH− instead of F− and receive the name of hydroxylbastnasite. Most bastnäsite is bastnäsite-(Ce), and cerium is by far the most common of the rare earths in this class of minerals. Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare-earth elements.
In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation from a specific source rock during sedimentary processes. The name is from the Spanish word placer, meaning "alluvial sand". Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, aeolian placers and paleo-placers.
Xenotime is a rare-earth phosphate mineral, the major component of which is yttrium orthophosphate (YPO4). It forms a solid solution series with chernovite-(Y) (YAsO4) and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium. The rare-earth elements dysprosium, erbium, terbium and ytterbium, as well as metal elements such as thorium and uranium (all replacing yttrium) are the expressive secondary components of xenotime. Due to uranium and thorium impurities, some xenotime specimens may be weakly to strongly radioactive. Lithiophyllite, monazite and purpurite are sometimes grouped with xenotime in the informal "anhydrous phosphates" group. Xenotime is used chiefly as a source of yttrium and heavy lanthanide metals (dysprosium, ytterbium, erbium and gadolinium). Occasionally, gemstones are also cut from the finest xenotime crystals.
Carbonatite is a type of intrusive or extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geochemical verification.
Various theories of ore genesis explain how the various types of mineral deposits form within Earth's crust. Ore-genesis theories vary depending on the mineral or commodity examined.
Kenmare Resources plc is a publicly traded mining company headquartered in Dublin, Republic of Ireland. Its primary listing is on the London Stock Exchange and it has a secondary listing on Euronext Dublin. Kenmare is one of the world's largest mineral sands producers and the Company owns and operates the Moma Titanium Minerals Mine. Moma is one of the world's largest titanium minerals deposits, located 160 km from the city of Nampula in Mozambique.
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. 89Y is the only stable isotope and the only isotope found in the Earth's crust.
An agpaitic rock is a peralkaline igneous rock, typically nepheline syenite or phonolite. Characteristic minerals in these rocks include complex silicates containing zirconium, titanium, sodium, calcium, the rare-earth elements, and fluorine. Agpaites are unusually rich in rare and obscure minerals such as eudialyte, wöhlerite, loparite, astrophyllite, lorenzenite, catapleiite, lamprophyllite, and villiaumite (NaF). Sodalite is typically present, but not diagnostic. Less alkaline igneous rocks in which zircon, titanite, and ilmenite are characteristic are called miaskitic.
Cerium is a chemical element; it has symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.
Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
Thor Lake is a deposit of rare metals located in the Blachford Lake intrusive complex. It is situated 5 km north of the Hearne Channel of Great Slave Lake, Northwest Territories, Canada, approximately 100 kilometers east-southeast of the capital city of Yellowknife. Geologically located on the Canadian Shield it is mostly composed of peralkaline syenite. The Blatchford Lake complex was created in the early Proterozoic, 2.14 Ga ago. The deposit is divided in several sub-structures. In a small zone at the northern edge of the syenite, the T-Zone, minerals like bastnäsite, phenakite and xenotime can be found.
Norra Kärr or Norra Kärr Alkaline Complex is an intrusive complex cropping out at the boundary between Östergötland and Småland, Sweden. The complex is chiefly made up of peralkaline nepheline syenite and is rich in exotic minerals. Rocks of the complex intruded into the Paleoproterozoic-aged Växjo granites of the Transscandinavian Igneous Belt. Alfred Elis Törnebohm was the first to describe the rocks of Norra Kärr in 1906. Norra Kärr was discovered a few years earlier during regional geological maping by the Swedish Geological Survey. The complex derives its name from a local farm, which translates into English as "Northern Fen". In 1968 Harry von Eckermann published his investigations on the complex defining its boundaries and confirming the view of it as an intrusion.
Regolith-hosted rare earth element deposits are rare-earth element (REE) ores in decomposed rocks that are formed by intense weathering of REE-rich parental rocks in subtropical areas. In these areas, rocks are intensely broken and decomposed. Then, REEs infiltrate downward with rain water and they are concentrated along a deeper weathered layer beneath the ground surface.
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