Elements and Mineral Resources

The great majority of elements in the periodic table are extracted from minerals. These are called ores. The elements are ordered alphabetically, showing their chemical symbol and atomic number (Z).

Despite its abundance, it was considered a rare and expensive metal until 1886, when Charles M. Hall of the United States and Paul L. T. Héroult of France independently discovered an inexpensive system for obtaining pure aluminum by electrolysis of its oxide (Al2O3).

Gutenberg, the inventor of the printing press (1450), created his mobile type from an antimony and lead alloy, giving greater hardness to the lead and allowing it to be used multiple times in linotypes. At the same time, it permitted rapid melting in case of deterioration or the need for new fonts.

Obtained from arsenopyrite (iron arsenic sulfide), from nickel, cobalt, copper, and lead sulfides, as well as from realgar and orpiment, and from copper sulfides with gold.

Barite (barium sulfate) was assigned strategic mineral status by the EU in 2017.

Beryl in rare-metal pegmatites can occur with other minerals that contain commodities of commercial importance, such as cesium, lithium, and tantalum, as well as clay minerals, feldspar, muscovite, and high-purity quartz.

Known in the early fifteenth century, but was confused with lead and tin. In 1713 Claude Geoffroy the Younger (a French nobleman) identified it definitively.

Boron is widely distributed in the environment, including in soil, water, and animals, and it is essential to plant life.

Obtained from the water of some seas, from salt lakes, and from the brine associated with some oil deposits.

A by-product of the extraction of zinc from zinc sulfides such as sphalerite.

Stalactite and stalagmite formation in karst caves demonstrates the high of calcium carbonate content achieved over time by filtering water.

A component of CO2 gas, a pollutant causing global warming, acid rain, and climate change. Our civilization is constantly emitting large amounts of CO2 from the combustion of fossil fuels (oil, coal, natural gas), in addition to natural emissions from volcanoes and animal and plant metabolism.

Diamond ore deposits are confined to a few geological settings. Diamonds are typically found in ancient regions of the Earth’s crust, known as cratons. These are extensive parts that achieved long-term stability so have been poorly deformed over a long period.

Graphite ore deposits fall into three main categories: microcrystalline graphite deposits, recently named ‘graphitic carbon’ (Beyssac O, Rumble D (2014) Elements 10(6): 415–420. https://doi.org/10.2113/gselements.10.6.415 ); disseminated flake-graphite; and chip graphite (Robinson Jr GR, Hammarstrom JM, Olson DW (2017) Graphite (No. 1802-J). US Geological Survey. https://pubs.er.usgs.gov/publication/pp1802J ).

The main source of cesium is pollucite, a primary lithium-cesium-rubidium mineral. It is also found in association with lithium-rich, lepidolite-bearing, and petalite-bearing zoned granite pegmatites.

The main source of chlorine is halite (NaCl) and brines associated with the evaporitic deposits. Brine is a water solution with a high content of halite (NaCl), greater than 5%. The main halite deposits are saline flats characteristic of arid basins. They are shallow and dry apart from when storm flooding turns the saltpan and its surroundings into a temporary lake. Continental saline flats occupy the lowest areas of closed arid basins.

The primary mineral source of chromium (Cr) is chromite (Fe, Mg) Cr2O4. Chromite deposits can be classified into four deposit types: stratiform chromite; podiform chromite; placer chromite; and laterite.

Most cobalt deposits are associated with nickel deposits. These occur in two geological settings: magmatic sulfide deposits; and laterite deposits. Mines currently in operation exploit both kinds; however, laterite ore deposits comprise about 70% of known nickel–cobalt resources. Besides nickel and cobalt (frequently found in association), there are other important ore minerals of cobalt: as sulfides like cobaltite (CoAsS); arsenates like erythrite Co3(AsO4)2.8H2O; and arsenides like skutterudite (CoAs2-3).

The main copper ores are chalcopyrite (CuFeS2) and bornite (Cu5FeS4). Porphyry systems are the main source of copper’s mineralization.

Fluorite occurs as an accessory mineral in granite, granite pegmatites, and syenites, and is also found in hydrothermal deposits. The following deposit types are in order of importance.

According to USGS, most of the world’s gallium is from bauxite mining and from sphalerite. Bauxite deposits are traditionally regarded as the economic source of aluminum (Al); however, they are also an important source of gallium as a by-product, because its close geochemical affinity with Al enables gallium to substitute easily in rock-forming aluminosilicates such as feldspar. Gallium also shows an affinity with iron (Fe) and zinc (Zn), enabling it to substitute for these elements in common rock-forming minerals. Gallium can also be found in geochemical association with germanium (Ge), silicon (Si), indium (In), cadmium (Cd), and tin (Sn).

According to USGS (2021), germanium does not form specific deposits but occurs rather as a by-product in a variety of deposit types that contain copper, gold, lead, silver, and zinc. Germanium concentrations in sphalerite from these deposits are typically a few hundred parts per million. Because it is a by-product of metallurgical operations commonly fed by concentrates from any number of different deposits, it is difficult to track germanium production back to a specific location. The examples discussed below, however, are known to be significant contributors to major germanium-producing facilities.

Gold was mainly concentrated in the Earth's solid and compacted Fe–Ni core during the planet’s accretionary stage, along with other highly siderophile elements. During partial melting of the mantle, gold is derived from the magmatic fluids that circulated to the surface in various tectonic contexts (cratons, ocean basins, divergent margins, convergent basins, and transform boundaries). Tectonic models and related geological processes control the genesis of ores not only of gold but of other metal deposits in Earth's geology and history, including the opening and closing of ocean basins, orogenesis of mountain ranges and geological structures, the distribution of mineral resources, and paleoclimates.

Hafnium is always found associated with zirconium, because of their similar geochemical behavior. Zircon (ZrSiO4) is the most common naturally occurring zirconium- and hafnium-bearing mineral. Most zircon forms as a product of primary crystallization in igneous rocks.

Indium tends to occur in nature with base metals such as copper, silver, zinc, cadmium, tin, lead, and bismuth. As a mineral, indium can be found in sphalerite (ZnS), galena (PbS), cassiterite (SnO2), the stannite group, and roquesite (CuInS2).

Iodine is rarely found independently in nature, and is often combined with other elements, basically forming inorganic salts.

The platinum-group metals (PGMs) are found almost exclusively in ores associated with mafic and ultramafic rocks at very low concentrations. They can be subdivided into two main groups: the Ir-subgroup (IPGE: Os, Ir, and Ru); and the Pt-subgroup (PPGE: Pt, Pd, and Rh). The most common iridium mineral is irarsite, (Ir,Ru,Rh,Pt)AsS. This is commonly hosted in chromitites, forming layered intrusions as in the Bushveld Complex), or in ophiolitic podiform chromitites as in the Al’Ays ophiolite complex.

The primary mineral sources of iron (Fe) are magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH)), limonite (FeO(OH)·n(H2O)), and siderite (FeCO3). Iron mineralization is associated with several hydrothermal systems, such as banded-iron formations (BIF).

Lead is most commonly found in hydrothermal veins. Lead and zinc are often found together in several kinds of ore deposits, and less so copper and iron. Metals precipitate from ore fluids by various processes, depending on the specific local conditions.

Lithium is mostly found in granites and pegmatite rocks, brines (salt solution), seawater, and clays. It typically occurs as a minor component in minerals. There are more than 100 minerals known potentially to contain lithium, but only a few are currently economic to exploit.

Magnesium is the eighth-most abundant element in the Earth’s crust, constituting about 2%, and in seawater it is the third most abundant element, excluding hydrogen and oxygen, after sodium salts.

According to (USGS (2021) Commodity statistics and information. Manganese. Available at: https://www.usgs.gov/centers/nmic/manganese-statistics-and-information (last accessed May 2021).), the main minerals from which to obtain manganese are pyrolusite (MnO2) and manganite (MnO(OH).

Metallic mercury (Hg) is obtained mainly from cinnabar (HgS), which has a characteristic bright scarlet color.

The main molybdenum ores are molybdenite (MoS2), wulfenite (PbMoO4), and powellite (CaMoO4). Porphyry systems are the main source of molybdenum minerals. Porphyry ore systems take their name from the porphyritic texture of mineralized intrusions that originate from high-temperature magmatic-hydro-thermal fluids. They are characterized by large tonnage yet low grade.

The most common nickel ores are pentlandite [(Ni,Fe)9S8] and garnierite [(Ni,Mg)6[(OH)8Si4O10]. Garnierite is the general name for the nickel-magnesium hydrosilicates that occur in many nickel–cobalt laterite deposits. Most economic nickel deposits occur in one of two types of geological environments: magmatic sulfide deposits or laterite deposits. Operational mines are divided equally between both; however, according to the USGS, laterites account for about 70% of known nickel–cobalt resources.

The columbite group is the primary ore for niobium, referring back to its old name. Niobium and tantalum are usually related. The columbite group includes minerals of varying proportions in their composition, with varying proportions of Nb or Ta in composition.

The platinum-group metals (PGMs) are found almost exclusively at very low concentrations in ores associated with mafic and ultramafic rocks. They can be subdivided into the Ir-subgroup (IPGE: Os, Ir, and Ru) and the Pt-subgroup (PPGE: Pt, Pd, and Rh). The most abundant PGMs are in the laurite–erlichmanite (RuS2–OsS2) series. These are commonly hosted in chromitites forming layered intrusions as in the Bushveld Complex, or in ophiolitic podiform chromitites as in Al’Ays ophiolite complex.

The platinum-group metals (PGMs) are almost exclusively found at very low concentrations in ores associated with mafic and ultramafic rocks. They can be divided into the Ir-subgroup (IPGE: Os, Ir, and Ru) and the Pt-subgroup (PPGE: Pt, Pd, and Rh). PGMs are a group of six minerals in which at least one of the six is essential to the composition of each mineral. A single major magmatic PGM ore deposit currently provides ~ 80% of worldwide demand for PGM: the Bushveld Complex in South Africa, which hosts about 80% of the world’s platinum resources. Several palladium minerals are known, and all are very rare. An example is braggite (Pt, Pd, Ni)S.

Phosphate deposits are widespread throughout the world, occurring on all continents and dating from the Precambrian to the Holocene. In terms of origin there are two main sources of phosphate deposit: sedimentary or igneous.

The platinum-group metals (PGMs) are found almost exclusively at very low concentrations in ores associated with mafic and ultramafic rocks. They can be divided into two main groups: the Ir-subgroup (IPGE: Os, Ir, and Ru) and the Pt-subgroup (PPGE: Pt, Pd, and Rh). The PGMs are a group for which at least one of the six minerals is essential to the composition. One major magmatic PGM ore deposit currently provides ~ 80% of worldwide demand for PGMs: the Bushveld Complex in South Africa (hosting about 80% of platinum resources). Sperrylite (PtAs2) and Pt–Pd-Rh ± (base metal) alloys are the main platinum ores.

The characteristic mineral source of potassium is sylvite (KCl). Sylvite is frequently observed associated with halite (NaCl), forming the mix known as sylvinite. In most cases, relatively pure sylvinite exists with essentially no soluble sulfate or other salts, yet it can occasionally be associated with carnallite (KMgCl3·6H20), with a similar crystalline structure and nearly free from other soluble salts.

The radium-223 isotope is made artificially from a generator containing actinium-227, similar to preparing technetium-99 m from molybdenum-99 (see: technetium).

Chuquicamata, in northern Chile, is the world’s largest porphyry copper ore body with molybdenite. Roasting the molybdenite emits gases, and the renium can then be extracted.

The platinum-group metals (PGMs) are almost exclusively found at very low concentrations in ores associated with mafic and ultramafic rocks. They can be subdivided into two main groups: the Ir-subgroup (IPGE: Os, Ir, and Ru); and the Pt-subgroup (PPGE: Pt, Pd, and Rh). PGM minerals are a group in which at least one of the six PGM is essential to the mineral composition. Pt–Pd–Rh ± (base metals) alloys are the main platinum ore. Rh minerals are very rare, and zaccarinite (RhNiAs) is an example.

Rubidium replaces potassium or cesium in the composition of many minerals. Lepidolite ((KLi2Al(Al,Si)3O10(F,OH)2) is the most common source of rubidium. Rubidium also occurs in leucite (KAlSi2O6), carnallite (KCl · MgCl2 · 6(H2O)), zinnwaldite (KLiFeAl(AlSi3)O10(OH,F)2), and pollucite (Cs(Si2Al)O6 · nH2O). It is considered to be an incompatible element, meaning that during the magma crystallization process it is concentrated with other heavy elements like cesium in the liquid phase, crystallizing last. Therefore, the largest deposits of rubidium come from pegmatite orebodies. Two notable sources of rubidium are the Bernic Lake deposit in Manitoba (Canada) and the island of Elba (Italy), which is rich in rubicline ((Rb,K)AlSi3O8). The largest Canadian producers of cesium also produce rubidium as a by-product.

The platinum-group metals (PGMs) are found almost exclusively at very low concentrations in ores associated with mafic and ultramafic rocks. They can be subdivided into the Ir-subgroup (IPGE: Os, Ir, and Ru) and the Pt-subgroup (PPGE: Pt, Pd, and Rh). The most abundant PGM are the laurite–erlichmanite (RuS2–OsS2) series. These are commonly hosted in chromitites, forming layered intrusions as in the Bushveld Complex) or in ophiolitic podiform chromitites as in the Al’Ays ophiolite complex.

Selenium is found in several deposit types, such as magmatic, volcanic, hydrothermal, and exogenic. It is found substituted into sulfide minerals such as chalcopyrite, cinnabar, cobaltite (CoAsS), galena, molybdenite, pentlandite, pyrite, pyrrhotite, sphalerite, and stibnite. Selenide minerals are less common than selenium-bearing sulfides, but phases such as clausthalite (PbSe), guanajuatite (Bi2Se3), naumannite (Ag2Se), and penroseite (blockite) ((Ni,Co,Cu)Se2) are found in the veins and stockworks of hydrothermal deposits.

Silica is present in multiple forms and minerals, but its most common form is quartz (SiO2). Quartz is the most abundant compound in the Earth’s crust, comprising roughly 14%. Quartz crystallization occurs when silica is heated. During the cooling process, silicon and oxygens recombine as molecules formed of one silicon atom and four oxygen atoms. Quartz is found in all rock types, such as granite, gneiss, and sandstone. Silicon is mined both as sand and as vein or lode deposits. However, the high-availability silicon usually extracted from silica sand refers to sands with the composition and grain-size distribution required for industrial application. Silicon is produced by heating silica sand to temperatures around 2200 °C.

Silver is commonly found in hydrothermal veins. Gold and silver are often found together, less so with metals like lead, zinc, copper, and iron, in several kinds of ore deposits. Metals precipitate from ore fluids by various processes depending on specific local conditions. The most common processes are cooling, mixing with other fluids, and pH change.

The main mineral source of sodium is halite. Halite can be found as a mineral (NaCl) or dissolved in water, forming brine. Brine is a solution with a high salt concentration, between 5% and 26 to 28%. Both halite and brine are closely associated with evaporite deposits, which may have either a lacustrine or marine origin.

Two strontium-bearing minerals, celestine (SrSO4) and strontianite (SrCO3), contain strontium in quantities sufficient to make their recovery worthwhile. Celestine is more common than strontianite and is the primary source of the world’s strontium. Celestine appears as crystals and as massive or fibrous aggregates in sedimentary rocks. It often displays a delicate blue coloration owing to the presence of impurities. Celestine can be found in bedded evaporite deposits in conjunction with gypsum, anhydrite, and halite. It can also occur in cavities within carbonate rocks where it has been precipitated from strontium-bearing groundwater or brines. Strontianite is formed in hydrothermal deposits at low temperatures in limestone and marl or as a secondary mineral in sulfide veins.

Elemental sulfur constitutes a metastable, intermediate state in the geological conversion of sulfate to sulfide or vice versa. Sulfur sedimentary deposits are formed from hydrogen sulfide resulting from the chemical reaction of sulfate with organic matter. Another possible sulfur origin was formed during or after formation of the enclosing rock. The geological bacterial sulfur cycle is another sulfur source, when oxidizing and reducing bacteria can occur side by side, and the active stage cannot be determined simply by locating the bacteria. Sulfur historically was usually obtained in pyrite (S2Fe). The Iberian Pyrite Belt was the most important sulfur source for decades.

The primary ore of tantalum is the columbite-tantalite group. The columbite group is a solid solution with varying proportions of Nb or Ta in its composition. According to the International Mineralogical Association (IMA), ‘tantalite’ or ‘coltan’ are not scientific names, yet they are widely used. Many specimens commonly named tantalite are actually minerals of the columbite or tapiolite group.

Technetium-99 m is one of the most widely used radiopharmaceuticals (about 83%) in diagnostic procedures for organ functioning in the human body (heart, brain, thyroid, lungs, bones, and blood). This metastable isotope, with a half-life of 6 h, is injected into the patient and accumulates in several parts of the body, concentrating in altered parts and emitting 140 keV gamma radiation detectable by gammagraphy (SPECT) devices.

Tellurium is found mainly as epithermal deposits and occurs in telluride minerals as native tellurium, and as tellurium-bearing sulfosalts in unoxidized ores, as well as in the form of tellurites in secondary ores. Epithermal gold and silver deposits, such as sylvanite (Au,Ag)2Te4) and calaverite (AuTe2), can also be a source of tellurium, such as in Colorado, in New Mexico in the United States, and in Japan.

Thallium is mostly found in association with potassium minerals in clays, soils, and granites, but it is not commonly commercially recoverable from those sources. The major source of commercial thallium is trace amounts found in the sulfide ores of copper, lead, zinc, and other metals.

According to the International Atomic Energy Agency (IAEA), thorium does not occur in its metallic form in nature because it is markedly oxyphile, thus occurs as oxide (thorianite (ThO2)), silicates (thorite (Th,U)SiO4), and phosphates (frequently with rare earth elements).

The primary mineral source of tin is cassiterite (SnO2). Tin’s mineralization is commonly associated with igneous intrusion and related ore systems. The classic tin deposit is greisen, an ore deposit characterized by a hydrothermally altered granitic rock. The mineralogical alteration is mostly composed of albite, quartz, and mica, common in European tin deposits. However, there are other tin deposit types, such as vein systems, anorogenic ring complexes, and breccia pipes. In some cases there may be spatial, temporal, and genetic links to classical intrusive ore deposits as porphyry and epithermal systems.

Titanium is the ninth-most abundant element in Earth’s crust and, although it is not found as a pure metal in nature, it is found in nearly all rocks and sediments. It has a strong affinity for oxygen, typically forming oxide minerals, mainly ilmenite (FeTiO3) and rutile (TiO2) but also with other titanium dioxide polymorphs such as anatase and brookite. There are basically types of three titanium-deposit types.

The common mineral source of tungsten (W) is wolframite (Fe2+)WO4 to (Mn2+)WO4). Tungsten’s mineralization is commonly associated with igneous intrusion and related ore systems. The classic type of tungsten deposit is greisen, a kind of ore deposit characterized by a hydrothermally altered granitic rock.

Uranium occurs in a number of geological environments. The major uranium primaries ore minerals are uraninite (UO2) or pitchblende (U3O8). However, a range of other uranium minerals, such as carnotite (K2(UO2)2(VO4)2·3H2O) or brannerite (U,Ca,Y,Ce)(Ti,Fe)2O6 and secondary like gummite (secondary uranium oxides (yellow-orange)), autunite (Ca(UO2)2(PO4)2.10-12H2O), torbernite (Cu(UO2)2(PO4)2.8-12H2O), or saleeite (Mg(UO2)2(PO4)2.10H2O) are found in particular deposits (IAEA 2021).

Vanadium occurs in nature in a wide variety of minerals. The following four main types of mineral deposits are recognized: vanadiferous titanomagnetite (VTM); sandstone-hosted vanadium (SSV); shale-hosted; and vanadates.

Zinc is most commonly found in hydrothermal veins. Zinc and lead are often found together, less so with copper and iron, in several kinds of ore deposits. Metals precipitate from ore fluids by various processes, depending on the specific local conditions.

Zircon (ZrSiO4) is the most common naturally occurring zirconium-bearing mineral. Most zircon forms as a product of primary crystallization in igneous rocks, and it is always associated with hafnium. The world’s largest primary deposit of zirconium associated with alkaline igneous rocks is in a single locality on the Kola Peninsula of Murmanskaya Oblast, Russia, where baddeleyite (zirconium oxide) is recovered as a by-product of mining apatite and magnetite. However, it is a special case because at present there are few primary igneous deposits of zirconium-bearing minerals of economic value.

At the end of 2019, China remained the world leader in rare earth production and refinery, responsible for a proportion in the order of 77% (Roskill 2021). Australia is some way behind in terms of production, then come countries such as the United States, Myanmar, Russia, India, and Thailand, among others.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations. For instance, the class of copper-gold-uranium-REE-iron (IOCG) includes the well-known Olympic Dam deposit (South Australia), the iron deposits of Kiruna (Sweden), the iron-REE deposits of Box Bixby and Pea Ridge (Missouri, United States) and possibly the REE-rich Bayan Obo (Mongolia), the Palabora carbonatite-hosted copper, and the Vergenoug iron-fluorine deposit (South Africa). When examined in detail, these deposits are remarkably different.

Promethium is used as a source of beta radiation to measure thickness. It is deployed as a light source for signals that require reliable and independent operation, along with phosphorus, which absorbs beta radiation and produces phosphorescence light.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations.

Approximately 90% of global production is from the Bayan Obo deposit in China, where scandium is a by-product of mining other REE and iron. It is hosted mostly by aegirine, although a small but significant proportion is present in bastnäsite-Ce, monazite-Ce, and fluorite.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations.

The variations are substantial within the REE class of ore deposits, and the formation of an REE ore deposit gives little information about its classification. Besides, classifying REE ore deposits on the basis of only their genetic evolution would quickly induce misinterpretations.

In this part of the book you will find most of what are termed the industrial minerals (generally excluding metals and mineral fuels) of high economic value that, rather than because of the compounds or elements that can be extracted from them, are used directly, depending on their physical or chemical properties either in industrial processes or after appropriate preparation.

Andalusite is an aluminum silicate (Al2SiO5), sharing its chemical composition with kyanite and sillimanite. These three minerals are polymorphs, and are often summarized as the sillimanite minerals.

Limestone is a sedimentary rock comprised chiefly of calcium carbonate (CaCO3). Deposits are extensive around the world. Therefore, there is a high variability of limestone deposits. Typically, they are formed in two main environments.

Corundum is an aluminum oxide (Al2O3). It is a relatively scarce mineral that appears in aluminous rocks, usually metamorphic, such as marbles, micaceous shales, and gneisses.

Dolomite is a calcium magnesium carbonate with the chemical composition CaMg(CO3)2, constituting a rock-forming mineral found in abundance around the world. It has numerous commercial uses.

Feldspars form an extensive group of silicate minerals. They constitute about 50% of the Earth’s crust, therefore they are found globally in igneous, metamorphic, and sedimentary rocks.

Gypsum deposits are widespread all over the world from many geological periods. Gypsum is one of the main minerals in sedimentary rocks, and it can be found in a range of mineral varieties.

Kaolin is a hydrated aluminum silicate crystalline mineral (kaolinite, Al2(Si2O5)(OH)4). It was termed ‘China clay’ from its use in China, formed commonly from weathered granite or hydrothermal activity. It is typical of three main geological environments: (1) weathering profiles; (2) hydrothermal alterations; and (3) sedimentary rocks. Kaolin is commonly a secondary mineral produced by feldspar and muscovite alteration, thus it is easily formed and is widespread in soils developed under hot, wet, intertropical climates. As a consequence, detrital kaolin minerals are important components of the sedimentary rocks deposited near these areas.

The main source of magnesium is magnesite (MgCO3). Magnesite usually forms during the alteration of magnesium-rich rocks or carbonate rocks by metamorphism or chemical weathering. Magnesites can be divided into three categories based on their crystal characteristics and metallogenic environment.

Mica constitutes a group of hydrous aluminum silicate minerals. Their characteristic crystalline structure forms layers that can be cleaved into very thin sheets. Mica crystals range in size from a few centimeters to several meters. They have a wide range of colors, from green or purple to almost colorless. Muscovite and phlogopite are the most economically significant micas, and their main ore deposit is pegmatites.

Phosphate rock resources originate predominantly in sedimentary marine phosphorites. Sedimentary phosphates (mostly phosphorites) are the main source of phosphate rock. Modern phosphorites are characterized by grains of cryptocrystalline or amorphous carbonate (CO3)–fluorapatite (Ca5(PO4)3F), variously referred as collophane or francolite, occurring as beds varying in thickness from a few centimeters up to tens of meters.

Halite (NaCl) is the usual mineral source of sodium. The main halite deposits are the saline flats typical of arid basins. A flat is a shallow depression with layered salts, and it remains dry until storm flooding turns it and the surrounding area into a temporary lake. Continental saline flats occupy the lowest parts of closed arid basins.

Sepiolite is a hydrated magnesium silicate with a microfibrous morphology and a particular texture that provides a high specific surface area. Together with palygorskite, it forms the palygorskite–sepiolite series. The usual settings for sepiolite occurrences range from soils to marine and lacustrine deposits, hydrothermal veins in serpentinite, diorite, and dolostone, and the weathering of volcanic rocks.

Quartz (SiO2) is a tectosilicate belonging to the silica group. It is widely used in industry for its hardness, resistance to chemical attacks, and so on, especially synthetic quartz, which is not twinned thus has perfect crystals that exploit its piezo-electric properties to the full.

The most characteristic mineral source of potassium is sylvite (KCl). Nevertheless, it is frequently observed associated with halite (NaCl), forming the mix known as sylvinite. In most cases, relatively pure sylvinite essentially has no soluble sulfate or other salts. It can occasionally be associated with carnallite (KMgCl3·6H20), with a similar crystalline structure and nearly free from other soluble salts.

Talc is hydrated magnesium silicate (Mg3Si4O10(OH)2); however, it may contain mineral impurities such as chlorites and fibrous amphiboles, calcite, magnesite, and dolomite. Talc has a characteristic perfect-basal exfoliation known as lamellarity or platiness due to low- to moderate-grade metamorphism during its formation.

Thenardite is a sodium sulfate salt (Na2SO4) usually found together with other sulfate salts such as mirabilite or Glauber's salt (Na2SO4·10H2O), glauberite (Na2Ca(SO4)2), bloedite or astrakanite (Na2Mg(SO4)2·4H2O), or burkeite (Na6(CO3)(SO4)2).

Wollastonite (CaSiO3) is a vital mineral because of its utility in industry. It is a typical calc-silicate formed in skarn environments. Skarn is defined by its mineralogy, usually characterized by a calc-silicate assemblage of mainly garnet, pyroxene, and amphibole, besides wollastonite. In general, skarn is formed during regional or contact metamorphism by a variety of metasomatic processes.

Zeolites form a group of minerals found in low-temperature hydrothermal systems, especially in volcanic and volcanically derived rocks but also in a wide range of other types, typically feldspathic and also metamorphic.