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The Minerals Portal
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.
The geological definition of mineral normally excludes compounds that occur only in living organisms. However, some minerals are often biogenic (such as calcite) or organic compounds in the sense of chemistry (such as mellite). Moreover, living organisms often synthesize inorganic minerals (such as hydroxylapatite) that also occur in rocks.
The concept of mineral is distinct from rock, which is any bulk solid geologic material that is relatively homogeneous at a large enough scale. A rock may consist of one type of mineral or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases.
Some natural solid substances without a definite crystalline structure, such as opal or obsidian, are more properly called mineraloids. If a chemical compound occurs naturally with different crystal structures, each structure is considered a different mineral species. Thus, for example, quartz and stishovite are two different minerals consisting of the same compound, silicon dioxide. (Full article...)
Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the processes of mineral origin and formation, classification of minerals, their geographical distribution, as well as their utilization. (Full article...)
Selected articles
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Image 1
Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.
Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high dispersion. Owing to these properties, it is useful for the manufacture of certain optical elements, especially polarization optics, for longer visible and infrared wavelengths up to about 4.5 micrometres. Natural rutile may contain up to 10% iron and significant amounts of niobium and tantalum.
Rutile derives its name from the Latin rutilus ('red'), in reference to the deep red color observed in some specimens when viewed by transmitted light. Rutile was first described in 1803 by Abraham Gottlob Werner using specimens obtained in Horcajuelo de la Sierra, Madrid (Spain), which is consequently the type locality. (Full article...) -
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Kaolinite (/ˈkeɪ.ələˌnaɪt, -lɪ-/ KAY-ə-lə-nyte, -lih-; also called kaolin) is a clay mineral, with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6).
Kaolinite is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. It has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g).
Rocks that are rich in kaolinite, and halloysite, are known as kaolin (/ˈkeɪ.əlɪn/) or china clay. In many parts of the world kaolin is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lower concentrations of iron oxide yield the white, yellow, or light orange colors of kaolin. Alternating lighter and darker layers are sometimes found, as at Providence Canyon State Park in Georgia, United States.
Kaolin is an important raw material in many industries and applications. Commercial grades of kaolin are supplied and transported as powder, lumps, semi-dried noodle or slurry. Global production of kaolin in 2021 was estimated to be 45 million tonnes, with a total market value of $US4.24 billion. (Full article...) -
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Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools. They are also the reason that diamond anvil cells can subject materials to pressures found deep in the Earth.
Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions are boron and nitrogen). Small numbers of defects or impurities (about one per million of lattice atoms) can color a diamond blue (boron), yellow (nitrogen), brown (defects), green (radiation exposure), purple, pink, orange, or red. Diamond also has a very high refractive index and a relatively high optical dispersion.
Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between 150 and 250 kilometres (93 and 155 mi) in the Earth's mantle, although a few have come from as deep as 800 kilometres (500 mi). Under high pressure and temperature, carbon-containing fluids dissolved various minerals and replaced them with diamonds. Much more recently (hundreds to tens of million years ago), they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites.
Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gases by chemical vapor deposition (CVD). Imitation diamonds can also be made out of materials such as cubic zirconia and silicon carbide. Natural, synthetic, and imitation diamonds are most commonly distinguished using optical techniques or thermal conductivity measurements. (Full article...) -
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Graphite (/ˈɡræfaɪt/) is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on a large scale (1.3 million metric tons per year in 2022) for uses in pencils, lubricants, and electrodes. Under high pressures and temperatures it converts to diamond. It is a good (but not excellent) conductor of both heat and electricity. (Full article...) -
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The mineral pyrite (/ˈpaɪraɪt/ PY-ryte), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.
Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.
The name pyrite is derived from the Greek πυρίτης λίθος (pyritēs lithos), 'stone or mineral which strikes fire', in turn from πῦρ (pŷr), 'fire'. In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what is now called pyrite.
By Georgius Agricola's time, c. 1550, the term had become a generic term for all of the sulfide minerals. (Full article...) -
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Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The word crystallography is derived from the Ancient Greek word κρύσταλλος (krústallos; "clear ice, rock-crystal"), and γράφειν (gráphein; "to write"). In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming that 2014 would be the International Year of Crystallography.
Before the development of X-ray diffraction and X-ray crystallography (see below), the study of crystals was based on physical measurements of their geometry using a goniometer. This involved measuring the angles of crystal faces relative to each other and to theoretical reference axes (crystallographic axes), and establishing the symmetry of the crystal in question. The position in 3D space of each crystal face is plotted on a stereographic net such as a Wulff net or Lambert net. The pole to each face is plotted on the net. Each point is labelled with its Miller index. The final plot allows the symmetry of the crystal to be established.
Crystallographic methods depend mainly on analysis of the diffraction patterns of a sample targeted by a beam of some type. X-rays are most commonly used; other beams used include electrons or neutrons. Crystallographers often explicitly state the type of beam used, as in the terms X-ray crystallography, neutron diffraction and electron diffraction. These three types of radiation interact with the specimen in different ways.- X-rays interact with the spatial distribution of electrons in the sample.
- Neutrons are scattered by the atomic nuclei through the strong nuclear forces, but in addition, the magnetic moment of neutrons is non-zero. They are therefore also scattered by magnetic fields. When neutrons are scattered from hydrogen-containing materials, they produce diffraction patterns with high noise levels. However, the material can sometimes be treated to substitute deuterium for hydrogen. Because of these different forms of interaction, the three types of radiation are suitable for different crystallographic studies.
- Electrons are charged particles and therefore interact with the total charge distribution of both the atomic nuclei and the electrons of the sample.
It is hard to focus x-rays or neutrons, but since electrons are charged they can be focused and are used in electron microscope to produce magnified images. There are many ways that transmission electron microscopy and related techniques such as scanning transmission electron microscopy, high-resolution electron microscopy can be used to obtain images with in many cases atomic resolution from which crystallographic information can be obtained. There are also other methods such as low-energy electron diffraction, low-energy electron microscopy and reflection high-energy electron diffraction which can be used to obtain crystallographic information about surfaces. (Full article...) -
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Asbestos (/æsˈbɛstəs, æz-, -tɒs/ ass-BES-təs, az-, -toss) is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre (particulate with length substantially greater than width) being composed of many microscopic "fibrils" that can be released into the atmosphere by abrasion and other processes. Inhalation of asbestos fibres can lead to various dangerous lung conditions, including mesothelioma, asbestosis, and lung cancer. As a result of these health effects, asbestos is considered a serious health and safety hazard.
Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots, but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties. Asbestos is an excellent thermal and electrical insulator, and is highly fire resistant, so for much of the 20th century, it was very commonly used across the world as a building material, until its adverse effects on human health were more widely acknowledged in the 1970s. Many buildings constructed before the 1980s contain asbestos.
The use of asbestos for construction and fireproofing has been made illegal in many countries. Despite this, at least 100,000 people are thought to die each year from diseases related to asbestos exposure.[citation needed] In part, this is because many older buildings still contain asbestos; in addition, the consequences of exposure can take decades to arise. The latency period (from exposure to the diagnosis of negative health effects) is typically 20 years. The most common diseases associated with chronic asbestos exposure are asbestosis (scarring of the lungs due to asbestos inhalation) and mesothelioma (a type of cancer).
Many developing countries still support the use of asbestos as a building material, and mining of asbestos is ongoing, with the top producer, Russia, having an estimated production of 790,000 tonnes in 2020. (Full article...) -
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Borax (also referred to as sodium borate, tincal (/ˈtɪŋkəl/) and tincar (/ˈtɪŋkər/)) is a salt (ionic compound), a hydrated or anhydrous borate of sodium, with the chemical formula Na2H20B4O17 (also written as Na2B4O7·10H2O).
It is a colorless crystalline solid that dissolves in water to make a basic solution.
It is commonly available in powder or granular form and has many industrial and household uses, including as a pesticide, as a metal soldering flux, as a component of glass, enamel, and pottery glazes, for tanning of skins and hides, for artificial aging of wood, as a preservative against wood fungus, and as a pharmaceutic alkalizer. In chemical laboratories, it is used as a buffering agent.
The terms tincal and tincar refer to native borax, historically mined from dry lake beds in various parts of Asia. (Full article...) -
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Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al2O3) with trace amounts of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name sapphire is derived from the Latin word sapphirus, itself from the Greek word sappheiros (σάπφειρος), which referred to lapis lazuli. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires – 9 on the Mohs scale (the third hardest mineral, after diamond at 10 and moissanite at 9.5) – sapphires are also used in some non-ornamental applications, such as infrared optical components, high-durability windows, wristwatch crystals and movement bearings, and very thin electronic wafers, which are used as the insulating substrates of special-purpose solid-state electronics such as integrated circuits and GaN-based blue LEDs. Sapphire is the birthstone for September and the gem of the 45th anniversary. A sapphire jubilee occurs after 65 years. (Full article...) -
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Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With the exception of extremely rare native iron deposits, it is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, which is how ancient peoples first discovered the property of magnetism.
Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak. Small grains of magnetite are very common in igneous and metamorphic rocks.
The chemical IUPAC name is iron(II,III) oxide and the common chemical name is ferrous-ferric oxide. (Full article...) -
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Zeolite is a family of several microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula Mn+
1/n(AlO
2)−
(SiO
2)
x・yH
2O where Mn+
1/n is either a metal ion or H+. These positive ions can be exchanged for others in a contacting electrolyte solution. H+
exchanged zeolites are particularly useful as solid acid catalysts.
The term was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating a material, believed to have been stilbite, produced large amounts of steam from water that had been adsorbed by the material. Based on this, he called the material zeolite, from the Greek ζέω (zéō), meaning "to boil" and λίθος (líthos), meaning "stone".
Zeolites occur naturally, but are also produced industrially on a large scale. , 253 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known. Every new zeolite structure that is obtained is examined by the International Zeolite Association Structure Commission (IZA-SC) and receives a three-letter designation. (Full article...) -
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Cinnabar (/ˈsɪnəˌbɑːr/; from Ancient Greek κιννάβαρι (kinnábari)), or cinnabarite (/ˌsɪnəˈbɑːraɪt/), also known as mercurblende is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments.
Cinnabar generally occurs as a vein-filling mineral associated with volcanic activity and alkaline hot springs. The mineral resembles quartz in symmetry and it exhibits birefringence. Cinnabar has a mean refractive index near 3.2, a hardness between 2.0 and 2.5, and a specific gravity of approximately 8.1. The color and properties derive from a structure that is a hexagonal crystalline lattice belonging to the trigonal crystal system, crystals that sometimes exhibit twinning.
Cinnabar has been used for its color since antiquity in the Near East, including as a rouge-type cosmetic, in the New World since the Olmec culture, and in China since as early as the Yangshao culture, where it was used in coloring stoneware.
Associated modern precautions for the use and handling of cinnabar arise from the toxicity of the mercury component, which was recognized as early as ancient Rome. (Full article...) -
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Amethyst is a violet variety of quartz. The name comes from the Koine Greek αμέθυστος amethystos from α- a-, "not" and μεθύσκω (Ancient Greek) methysko / μεθώ metho (Modern Greek), "intoxicate", a reference to the belief that the stone protected its owner from drunkenness. Ancient Greeks wore amethyst and carved drinking vessels from it in the belief that it would prevent intoxication.
Amethyst, a semiprecious stone, is often used in jewelry. (Full article...) -
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Hematite (/ˈhiːməˌtaɪt, ˈhɛmə-/), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of Fe
2O
3. It has the same crystal structure as corundum (Al
2O
3) and ilmenite (FeTiO
3). With this it forms a complete solid solution at temperatures above 950 °C (1,740 °F).
Hematite naturally occurs in black to steel or silver-gray, brown to reddish-brown, or red colors. It is mined as an important ore mineral of iron. It is electrically conductive. Hematite varieties include kidney ore, martite (pseudomorphs after magnetite), iron rose and specularite (specular hematite). While these forms vary, they all have a rust-red streak. Hematite is not only harder than pure iron, but also much more brittle. Maghemite is a polymorph of hematite (γ-Fe
2O
3) with the same chemical formula, but with a spinel structure like magnetite.
Large deposits of hematite are found in banded iron formations. Gray hematite is typically found in places that have still, standing water or mineral hot springs, such as those in Yellowstone National Park in North America. The mineral can precipitate in the water and collect in layers at the bottom of the lake, spring, or other standing water. Hematite can also occur in the absence of water, usually as the result of volcanic activity.
Clay-sized hematite crystals can also occur as a secondary mineral formed by weathering processes in soil, and along with other iron oxides or oxyhydroxides such as goethite, which is responsible for the red color of many tropical, ancient, or otherwise highly weathered soils. (Full article...) -
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Chalcopyrite (/ˌkælkəˈpaɪˌraɪt, -koʊ-/ KAL-kə-PY-ryte, -koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.
On exposure to air, chalcopyrite tarnishes to a variety of oxides, hydroxides, and sulfates. Associated copper minerals include the sulfides bornite (Cu5FeS4), chalcocite (Cu2S), covellite (CuS), digenite (Cu9S5); carbonates such as malachite and azurite, and rarely oxides such as cuprite (Cu2O). It is rarely found in association with native copper. Chalcopyrite is a conductor of electricity.
Copper can be extracted from chalcopyrite ore using various methods. The two predominant methods are pyrometallurgy and hydrometallurgy, the former being the most commercially viable. (Full article...) -
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Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also crystallizes as translucent crystals of selenite. It forms as an evaporite mineral and as a hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on scratch hardness comparison.
Fine-grained white or lightly tinted forms of gypsum known as alabaster have been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. (Full article...) -
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Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant. It is an ingredient in ceramics, paints, and roofing material. It is a main ingredient in many cosmetics. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form.
The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 1 as the hardness of talc, the softest mineral. When scraped on a streak plate, talc produces a white streak, though this indicator is of little importance, because most silicate minerals produce a white streak. Talc is translucent to opaque, with colors ranging from whitish grey to green with a vitreous and pearly luster. Talc is not soluble in water, and is slightly soluble in dilute mineral acids.
Soapstone is a metamorphic rock composed predominantly of talc. (Full article...) -
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In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter.
The smallest group of particles in the material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive translation of the unit cell along its principal axes. The translation vectors define the nodes of the Bravais lattice.
The lengths of the principal axes, or edges, of the unit cell and the angles between them are the lattice constants, also called lattice parameters or cell parameters. The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space may be described by the 230 space groups.
The crystal structure and symmetry play a critical role in determining many physical properties, such as cleavage, electronic band structure, and optical transparency. (Full article...) -
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A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires. Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond. The word ruby comes from ruber, Latin for red. The color of a ruby is due to the element chromium.
Some gemstones that are popularly or historically called rubies, such as the Black Prince's Ruby in the British Imperial State Crown, are actually spinels. These were once known as "Balas rubies".
The quality of a ruby is determined by its color, cut, and clarity, which, along with carat weight, affect its value. The brightest and most valuable shade of red, called blood-red or pigeon blood, commands a large premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. Ruby is the traditional birthstone for July and is usually pinker than garnet, although some rhodolite garnets have a similar pinkish hue to most rubies. The world's most valuable ruby to be sold at auction is the Sunrise Ruby. (Full article...) -
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Andesite (/ˈændəzaɪt/) is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.
Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust.
The name andesite is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. (Full article...) -
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Micas (/ˈmaɪkəz/ MY-kəz) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists, and "books" (large individual crystals) of mica several feet across have been found in some pegmatites.
Micas are used in products such as drywalls, paints, fillers, especially in parts for automobiles, roofing and shingles, as well as in electronics. The mineral is used in cosmetics and food to add "shimmer" or "frost." (Full article...) -
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Beryl (/ˈbɛrəl/ BERR-əl) is a mineral composed of beryllium aluminium silicate with the chemical formula Be3Al2Si6O18. Well-known varieties of beryl include emerald and aquamarine. Naturally occurring hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, pink, and red (the rarest). It is an ore source of beryllium. (Full article...) -
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Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver.
Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite. (Full article...) -
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In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their point groups, and into lattice systems according to their Bravais lattices. Crystal systems that have space groups assigned to a common lattice system are combined into a crystal family.
The seven crystal systems are triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. Informally, two crystals are in the same crystal system if they have similar symmetries (albeit there are many exceptions). (Full article...) -
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Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon.
The Mohs scale of mineral hardness, based on scratch hardness comparison, defines value 4 as fluorite.
Pure fluorite is colourless and transparent, both in visible and ultraviolet light, but impurities usually make it a colorful mineral and the stone has ornamental and lapidary uses. Industrially, fluorite is used as a flux for smelting, and in the production of certain glasses and enamels. The purest grades of fluorite are a source of fluoride for hydrofluoric acid manufacture, which is the intermediate source of most fluorine-containing fine chemicals. Optically clear transparent fluorite has anomalous partial dispersion, that is, its refractive index varies with the wavelength of light in a manner that differs from that of commonly used glases, so fluorite is useful in making apochromatic lenses, making it valuable, particularly in photographic optics. Fluorite optics are also usable in the far-ultraviolet and mid-infrared ranges, where conventional glasses are too opaque for use. Fluorite also has low dispersion, and a high refractive index for its density, which can make it useful for some specialized purposes in optics. (Full article...)
Selected mineralogist
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Image 1
Karl Johann Bernhard Karsten (26 November 1782 – 22 August 1853) was a German mineralogist known for contributions made to the German metallurgy industry. (Full article...) -
Image 2
Charles Friedel (French: [fʁidɛl]; 12 March 1832 – 20 April 1899) was a French chemist and mineralogist. (Full article...) -
Image 3
Joseph Henry Collins FGS, (16 March 1841 – 12 April 1916) was a British mining engineer, mineralogist and geologist. He died at his home, Crinnis House, near St Austell, on 12 April 1916 and is buried in Campdowns cemetery, Charlestown. (Full article...) -
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Carl Franz Anton Ritter von Schreibers (15 August 1775 – 21 May 1852) was an Austrian naturalist who was a native of Pressburg, Hungary, Habsburg Empire (today Bratislava, Slovakia).
In 1847, an uncommon iron-nickel-phosphide ((Fe,Ni)3P) mineral was named in his honor by Wilhelm Karl Ritter von Haidinger (1775–1871). The mineral is found in meteorites, and is known today as schreibersite. As a zoologist, he was the first to perform a comprehensive anatomical study of the olm, a cave-dwelling, aquatic amphibian. The plant genus Schreibersia (synonym Augusta, family Rubiaceae) was named in his honor by Johann Baptist Emanuel Pohl.The common bent-wing bat (Miniopterus schreibersii), also known as the Schreibers's long-fingered bat or Schreibers's bat, is a species of insectivorous bat. They appear to have dispersed from a subtropical origin and distributed throughout the southern Palearctic, Ethiopic, Oriental, and Australian regions. In Europe, it is present in the southern half on the continent from Iberia to the Caucasus, with the largest populations found in the warmer Mediterranean area. The common and scientific names honor Carl Franz Anton Ritter von Schreibers. (Full article...) -
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Johan Georg Forchhammer (26 July 1794 – 14 December 1865) was a Danish mineralogist and geologist. (Full article...) -
Image 6
Arthur Moritz Schoenflies (German: [ˈʃøːnfliːs]; 17 April 1853 – 27 May 1928), sometimes written as Schönflies, was a German mathematician, known for his contributions to the application of group theory to crystallography, and for work in topology.
Schoenflies was born in Landsberg an der Warthe (modern Gorzów, Poland). Arthur Schoenflies married Emma Levin (1868–1939) in 1896. He studied under Ernst Kummer and Karl Weierstrass, and was influenced by Felix Klein. (Full article...) -
Image 7Henri Hureau de Sénarmont (6 September 1808 – 30 June 1862) was a French mineralogist and physicist.
He was born in Broué, Eure-et-Loir. From 1822 to 1826, he studied at the École Polytechnique in Paris, then furthered his education at the École des Mines. During the course of his career, he became engineer-in-chief of mines, and professor of mineralogy and director of studies at the École des Mines in Paris. (Full article...) -
Image 8
George Frederick Kunz (September 29, 1856 – June 29, 1932) was an American mineralogist and mineral collector. (Full article...) -
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Sir Henry Alexander Miers, FRS (25 May 1858 – 10 December 1942) was a British mineralogist and crystallographer.
Born in Rio de Janeiro, Brazil, he was educated at Eton College and Trinity College, Oxford. He was elected a Fellow of the Royal Society in 1896. (Full article...) -
Image 10Adolf Knop (12 January 1828, in Altenau – 27 December 1893, in Karlsruhe) was a German geologist and mineralogist.
He studied mathematics and sciences at the University of Göttingen, where he was a pupil of chemist Friedrich Wohler and mineralogist Johann Friedrich Ludwig Hausmann. From 1849 he taught classes at the vocational school in Chemnitz. In 1857 he became an associate professor of geology and mineralogy at the University of Giessen, where in 1863 he attained a full professorship. In 1866 he relocated to Karlsruhe as a professor at the Polytechnic school. In 1878 he succeeded Moritz August Seubert as manager of the Grand Ducal Natural History Cabinet. (Full article...) -
Image 11Rudolf Koechlin (11 November 1862 – 11 February 1939) was an Austrian mineralogist.
Koechlin was born and died in Vienna. He studied mineralogy, crystallography, petrology and geology at the University of Vienna, obtaining his doctorate in 1887 with a thesis on manganite, polianite and pyrolusite. At Vienna, his instructors included Gustav Tschermak and Albrecht Schrauf. In 1884 he began work as a volunteer in the mineralogical-petrography department of the Naturhistorisches Hofmuseum in Vienna. In 1897 he became a "custos-adjunct", later named a curator first-class (1912), and in 1920, was appointed director of the mineralogical-petrography department. (Full article...) -
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Arthur Hutchinson OBE FRS (6 July 1866 – 12 December 1937) was a British mineralogist. During World War I, and at the request of the Admiralty, he was asked to design gas masks suitable for the Navy; for his work, he was awarded the OBE. Hutchinson was elected a Fellow of the Royal Society in 1922. He was master of Pembroke College, Cambridge, from 1928 to 1937, served on the Council of the Royal Society from 1932 to 1934, and was the Society's Vice-President for the year 1933-34. (Full article...) -
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Christian Ernst Weiss (12 May 1833, in Eilenburg – 4 July 1890, in Schkeuditz) was a German mineralogist, geologist and palaeontologist.
He is not to be confused with the historian Christian Ernst Weiße (1766–1832). (Full article...) -
Image 14Leonard James Spencer CBE FRS (7 July 1870 – 14 April 1959) was a British geologist. He was an Honorary member of the Royal Geological Society of Cornwall, and also a recipient of its Bolitho Medal. He was president of the Mineralogical Society of Great Britain and Ireland from 1936 to 1939. In mineralogy, Spencer was an original investigator who described several new minerals, including miersite, tarbuttite and parahopeite. He also did important work as a curator, editor and bibliographer. He was the third person to receive the Roebling Medal, the highest award of the Mineralogical Society of America. In 1937, he was awarded the Murchison Medal of the Geological Society of London. He wrote at least 146 articles for the Encyclopædia Britannica Eleventh Edition.
His daughter, Penelope Spencer became a successful free-style dancer and choreographer. (Full article...) -
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Anders Jahan Retzius (3 October 1742 – 6 October 1821) was a Swedish chemist, botanist and entomologist. (Full article...) -
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Leonid Alekseyevich Kulik (Russian: Леонид Алексеевич Кулик; 19 August 1883 – 14 or 24 April 1942) was a Soviet mineralogist who is noted for his research into meteorites. (Full article...) -
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George Shirley Switzer (June 11, 1915 – March 23, 2008) was an American mineralogist who is credited with starting the Smithsonian Institution's famed National Gem and Mineral Collection by acquiring the Hope Diamond for the museum in 1958. Switzer made the arrangements when renowned New York City jeweler Harry Winston decided to donate the Hope Diamond to the Smithsonian.
Switzer was also known for his analysis of Moon rocks which were brought back by NASA missions to the Moon. (Full article...) -
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Brian Harold Mason (18 April 1917 – 3 December 2009) was a New Zealand geochemist and mineralogist who was one of the pioneers in the study of meteorites. He played a leading part in understanding the nature of the Solar System through his studies of meteorites and lunar rocks. He also examined and classified thousands of meteorites collected from Antarctica. (Full article...) -
Image 19Friedrich Klockmann (12 April 1858, Schwerin – 17 November 1937, Aachen) was a German geologist and mineralogist.
He studied geology and mineralogy at the Bergakademie in Clausthal and at the University of Rostock, receiving his doctorate in 1881. Following graduation he worked for the Prussian Geological Survey, based in Berlin. From 1887 he taught classes in mineralogy and geology at the academy in Clausthal, and in 1892 attained the title of professor. From 1899 he worked as a professor at the technical university in Aachen, where in 1917/18 he served as academic rector. (Full article...) -
Image 20Ernest (Ernie) Henry Nickel (born Ernst Heinrich Nickel on 31 August 1925 in Louth, Ontario, died on 18 July 2009) was a mineralogist from Canada who emigrated to Australia. He is best known as an editor of the ninth edition of the Nickel-Strunz classification together with Karl Hugo Strunz. (Full article...)
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Image 21
Samuel Fowler (October 30, 1779 – February 20, 1844) was a doctor, state legislator, and member of the United States House of Representatives from northwestern New Jersey. As the owner of zinc and iron mines and an iron works at Franklin, New Jersey, he became a noted mineralogist who discovered several varieties of rare minerals (chiefly various ores of zinc). (Full article...) -
Image 22
Karl Cäsar von Leonhard (12 September 1779 in Rumpenheim – 23 January 1862 in Heidelberg) was a German mineralogist and geologist. His son, Gustav von Leonhard, was also a mineralogist.
From 1797 he studied at the universities of Marburg and Göttingen, where Johann Friedrich Blumenbach was an important influence to his career. He collected many mineralogical specimens on scientific excursions in Saxony and Thuringia, continued by travel to the Austrian Alps (including the Salzkammergut). During his journeys he made the acquaintance of Friedrich Mohs and Karl von Moll. In 1818, through assistance from Baden minister of state Sigismund von Reitzenstein, he was appointed professor of mineralogy at the University of Heidelberg. (Full article...) -
Image 23Haldor Frederik Axel Topsøe (29 April 1842 in Skælskør, Slagelse Municipality, Denmark – 31 December 1935 in Frederiksberg, Denmark) was a Danish chemist and crystallographer. He is grandfather of the engineer Haldor Topsøe (1913–2013) who has got his name from his grandfather, and great-grandfather of the mathematician Flemming Topsøe (born 25 August 1938) and the engineer Henrik Topsøe (born 10 August 1944).
Topsøe took Magisterkonferens in chemistry in 1866 and doctorate for a chemical-crystallographical work of selenium-sour salts. He worked as assistant at the Natural History Museum 1863–1867 and at the chemistry laboratory of University of Copenhagen 1867–1873. In 1872, he received a gold medal of Royal Danish Academy of Sciences and Letters, of which he was member from 1877, for a great crystallographical-optical work together with the physicist Christian Christiansen (1843–1917). He worked as chemistry teacher at the Royal Danish Military Academy 1876–1902 where he founded a new laboratory where he continued his science works. In 1884 he participated in the oceanographic expedition to west Greenland on the gunboat HDMS Fylla. He was member of the Norwegian Academy of Science and Letters from 1892. (Full article...) -
Image 24Carl Adolf Ferdinand Hintze (17 August 1851, Breslau – 28 December 1916, Breslau) was a German mineralogist and crystallographer.
From 1868 he studied at the University of Breslau, where he was a student of Ferdinand von Roemer. He then furthered his education at the universities of Bonn and Berlin. Beginning in 1872 he served as an assistant to mineralogist Paul Heinrich von Groth at the University of Strasbourg. In 1875, eye problems along with financial issues forced him to abandon his scientific activity at the university, and he subsequently found employment as a trader in the minerals business. Since 1880 he worked as a scientific director for a private firm in Bonn. (Full article...) -
Image 25Erika Pohl-Ströher (18 January 1919 – 18 December 2016) was a German business executive, heiress, and collector of minerals and German folk art. She was resident in Switzerland for much of her life. (Full article...)
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For editor resources and to collaborate with other editors on improving Wikipedia's Minerals-related articles, see WikiProject Rocks and minerals.
General images
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Image 1Muscovite, a mineral species in the mica group, within the phyllosilicate subclass (from Mineral)
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Image 2Red cinnabar (HgS), a mercury ore, on dolomite. (from Mineral)
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Image 3Pink cubic halite (NaCl; halide class) crystals on a nahcolite matrix (NaHCO3; a carbonate, and mineral form of sodium bicarbonate, used as baking soda). (from Mineral)
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Image 5Mohs Scale versus Absolute Hardness (from Mineral)
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Image 7Black andradite, an end-member of the orthosilicate garnet group. (from Mineral)
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Image 9Diamond is the hardest natural material, and has a Mohs hardness of 10. (from Mineral)
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Image 10Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background (from Mineral)
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Image 12Sphalerite crystal partially encased in calcite from the Devonian Milwaukee Formation of Wisconsin (from Mineral)
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Image 13Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). (from Mineral)
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Image 15Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale (from Mohs scale)
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Image 16When minerals react, the products will sometimes assume the shape of the reagent; the product mineral is termed a pseudomorph of (or after) the reagent. Illustrated here is a pseudomorph of kaolinite after orthoclase. Here, the pseudomorph preserved the Carlsbad twinning common in orthoclase. (from Mineral)
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Image 17Schist is a metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent sillimanite porphyroblasts as large as 3 cm (1.2 in). (from Mineral)
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Image 18An example of elbaite, a species of tourmaline, with distinctive colour banding. (from Mineral)
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Image 21Native gold. Rare specimen of stout crystals growing off of a central stalk, size 3.7 x 1.1 x 0.4 cm, from Venezuela. (from Mineral)
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Image 22Gypsum desert rose (from Mineral)
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Image 23Epidote often has a distinctive pistachio-green colour. (from Mineral)
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Image 26Asbestiform tremolite, part of the amphibole group in the inosilicate subclass (from Mineral)
In the news
- 3 May 2024 –
- Panama bans First Quantum Minerals from extracting copper following the closure of its Cobre Panamá mine last year. (Reuters) (The Globe and Mail)
Did you know ...?
- ... that the uncommon mineral aguilarite (pictured), named for discoverer Ponciano Aguilar, is known from the Americas, Europe, Asia, and Australasia?
- ... that the thallium-rich mineral lorandite from the Allchar deposit is being used to determine the flux of solar neutrinos?
- ... that seamanite is known from only four locations, with three in Michigan and one in Australia?
- ...that jerrygibbsite ((Mn,Zn)9(SiO4)4(OH)2) is a rare mineral of which there are only five known samples in the world?
Subcategories
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Topics
Overview | ||
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Common minerals |
Ore minerals, mineral mixtures and ore deposits | |||||||||
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Ores |
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Deposit types |
Borates | |||||
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Carbonates | |||||
Oxides |
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Phosphates | |||||
Silicates | |||||
Sulfides | |||||
Other |
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Crystalline | |||||||
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Cryptocrystalline | |||||||
Amorphous | |||||||
Miscellaneous | |||||||
Notable varieties |
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Oxide minerals |
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Silicate minerals | |||||
Other |
Gemmological classifications by E. Ya. Kievlenko (1980), updated | |||||||||
Jewelry stones |
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Jewelry-Industrial stones |
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Industrial stones |
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Mineral identification | |
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"Special cases" ("native elements and organic minerals") |
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"Sulfides and oxides" |
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"Evaporites and similars" |
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"Mineral structures with tetrahedral units" (sulfate anion, phosphate anion, silicon, etc.) |
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