Portal:Minerals
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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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Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond as a form of carbon is a tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of electricity, and insoluble in water. 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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Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline forms of silica, which are considered minerals. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt.
The name opal is believed to be derived from the Sanskrit word upala (उपल), which means 'jewel', and later the Greek derivative opállios (ὀπάλλιος).
There are two broad classes of opal: precious and common. Precious opal displays play-of-color (iridescence); common opal does not. Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." The internal structure of precious opal causes it to diffract light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the most common. (Full article...) -
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Cleavage, in mineralogy and materials science, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye. If bonds in certain directions are weaker than others, the crystal will tend to split along the weakly bonded planes. These flat breaks are termed "cleavage". The classic example of cleavage is mica, which cleaves in a single direction along the basal pinacoid, making the layers seem like pages in a book. In fact, mineralogists often refer to "books of mica".
Diamond and graphite provide examples of cleavage. Each is composed solely of a single element, carbon. In diamond, each carbon atom is bonded to four others in a tetrahedral pattern with short covalent bonds. The planes of weakness (cleavage planes) in a diamond are in four directions, following the faces of the octahedron. In graphite, carbon atoms are contained in layers in a hexagonal pattern where the covalent bonds are shorter (and thus even stronger) than those of diamond. However, each layer is connected to the other with a longer and much weaker van der Waals bond. This gives graphite a single direction of cleavage, parallel to the basal pinacoid. So weak is this bond that it is broken with little force, giving graphite a slippery feel as layers shear apart. As a result, graphite makes an excellent dry lubricant.
While all single crystals will show some tendency to split along atomic planes in their crystal structure, if the differences between one direction or another are not large enough, the mineral will not display cleavage. Corundum, for example, displays no cleavage. (Full article...) -
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Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chalk is common throughout Western Europe, where deposits underlie parts of France, and steep cliffs are often seen where they meet the sea in places such as the Dover cliffs on the Kent coast of the English Channel.
Chalk is mined for use in industry, such as for quicklime, bricks and builder's putty, and in agriculture, for raising pH in soils with high acidity. It is also used for "blackboard chalk" for writing and drawing on various types of surfaces, although these can also be manufactured from other carbonate-based minerals, or gypsum. (Full article...) -
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Zircon (/ˈzɜːrkɒn, -kən/) 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 name derives from the Persian zargun, meaning "gold-hued". This word is changed into "jargoon", a term applied to light-colored zircons. The English word "zircon" is derived from Zirkon, which is the German adaptation of this word. Yellow, orange, and red zircon is also known as "hyacinth", from the flower hyacinthus, whose name is of Ancient Greek origin. (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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Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ion, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca10(PO4)6(OH,F,Cl)2, and the crystal unit cell formulae of the individual minerals are written as Ca10(PO4)6(OH)2, Ca10(PO4)6F2 and Ca10(PO4)6Cl2.
The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. Apatite is often mistaken for other minerals. This tendency is reflected in the mineral's name, which is derived from the Greek word ἀπατάω (apatáō), which means to deceive. (Full article...) -
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Corundum is a crystalline form of aluminium oxide (Al2O3) typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.
The name "corundum" is derived from the Tamil-Dravidian word kurundam (ruby-sapphire) (appearing in Sanskrit as kuruvinda).
Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. It is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood. Emery, a variety of corundum with no value as a gemstone, is commonly used as an abrasive. It is a black granular form of corundum, in which the mineral is intimately mixed with magnetite, hematite, or hercynite.
In addition to its hardness, corundum has a density of 4.02 g/cm3 (251 lb/cu ft), which is unusually high for a transparent mineral composed of the low-atomic mass elements aluminium and oxygen. (Full article...) -
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Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. 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 2014 the International Year of Crystallography.
Crystallography is a broad topic, and many of its subareas, such as X-ray crystallography, are themselves important scientific topics. Crystallography ranges from the fundamentals of crystal structure to the mathematics of crystal geometry, including those that are not periodic or quasicrystals. At the atomic scale it can involve the use of X-ray diffraction to produce experimental data that the tools of X-ray crystallography can convert into detailed positions of atoms, and sometimes electron density. At larger scales it includes experimental tools such as orientational imaging to examine the relative orientations at the grain boundary in materials. Crystallography plays a key role in many areas of biology, chemistry, and physics, as well new developments in these fields. (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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Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH)8·4H2O. It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.
Like most other opaque gems, turquoise has been devalued by the introduction of treatments, imitations, and synthetics into the market. The robin egg blue or sky blue color of the Persian turquoise mined near the modern city of Nishapur, Iran, has been used as a guiding reference for evaluating turquoise quality. (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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Tourmaline (/ˈtʊərməlɪn, -ˌliːn/ TOOR-mə-lin, -leen) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone comes in a wide variety of colors.
The name is derived from the Sinhalese tōramalli (ටෝරමල්ලි), which refers to the carnelian gemstones. (Full article...) -
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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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In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals.
There are three main varieties of these crystals:- Primitive cubic (abbreviated cP and alternatively called simple cubic)
- Body-centered cubic (abbreviated cI or bcc)
- Face-centered cubic (abbreviated cF or fcc)
Note: the term fcc is often used in synonym for the cubic close-packed or ccp structure occurring in metals. However, fcc stands for a face-centered-cubic Bravais lattice, which is not necessarily close-packed when a motif is set onto the lattice points. E.g. the diamond and the zincblende lattices are fcc but not close-packed.
Each is subdivided into other variants listed below. Although the unit cells in these crystals are conventionally taken to be cubes, the primitive unit cells often are not. (Full article...) -
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Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2. Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.
Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation from α-quartz to β-quartz takes place abruptly at 573 °C (846 K; 1,063 °F). Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold.
There are many different varieties of quartz, several of which are classified as gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Europe and Asia.
Quartz is the mineral defining the value of 7 on the Mohs scale of hardness, a qualitative scratch method for determining the hardness of a material to abrasion. (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 (though there are many exceptions). (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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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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Halite (/ˈhælaɪt, ˈheɪlaɪt/ HAL-yte, HAY-lyte), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride (NaCl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on inclusion of other materials, impurities, and structural or isotopic abnormalities in the crystals. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates. The name halite is derived from the Ancient Greek word for "salt", ἅλς (háls). (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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Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur. (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 glasses, so fluorite is useful in making apochromatic lenses, and particularly valuable 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. (Full article...) -
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Graphite (/ˈɡræfaɪt/) is a crystalline allotrope (form) of the element carbon. It consists of many stacked layers of graphene typically in the excess of hundred(s) of layers. 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 many critical industries including refractories (50%), lithium-ion batteries (18%), foundries (10%), lubricants (5%), among others (17%). Under extremely high pressures and extremely high temperatures it converts to diamond. It is a good conductor of both heat and electricity (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...)
Selected mineralogist
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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...) -
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Anton Schrötter von Kristelli (26 November 1802 – 15 April 1875) was an Austrian chemist and mineralogist born in Olomouc, Moravia. His son Leopold Schrötter Ritter von Kristelli (1837–1908) was a noted laryngologist. (Full article...) -
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Gustav von Leonhard (12 November 1816 in Munich – 27 December 1878 in Heidelberg) was a German mineralogist and geologist. He was the son of mineralogist Karl Cäsar von Leonhard.
He studied mineralogy and related sciences at the University of Heidelberg, receiving his doctorate in 1840. He continued his education in Berlin, and in 1841 obtained his habilitation at Heidelberg. In 1853 he became an associate professor of mineralogy at the University of Heidelberg. (Full article...) -
Image 4Leonard 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...) -
Image 5Martine de Bertereau, also known as Baroness de Beausoleil, (c. 1600 – after 1642) was the first recorded female mineralogist as well as mining engineer along with her husband, Jean de Chastelet. She traveled extensively throughout Europe in search of mineral deposits and fresh ground water under the employment of various nobles and royals. During the reign of the French King, Louis XIII, Martine and her husband surveyed the sites of potential mines in France. During one of their mining expeditions Martine and her family were accused of witchcraft and fled to Hungary. Later, Martine, her husband and oldest daughter were arrested and eventually died in prison sometime after 1642. During her life, she produced multiple pieces of literature derived largely from the Roman engineer Vitruvius's book on architecture, De architectura. Her writings describe the use of divining-rods, similar to dowsing, as well as other renowned scientific ideas. Martine de Bertereau was not forthcoming about her use of different scientific ideas, and preferred the public to believe she was using magic, or renowned ancient scientific ideas. Her success came from her development in the understanding of the geologic world around her. It is uncertain of her reasoning behind the decision to lie about her actual means of success. Her literature provides a unique glimpse into the craft and skills required to mine in the seventeenth century. (Full article...)
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Axel Hamberg (17 January 1863 – 28 June 1933) was a Swedish mineralogist, geographer and explorer. (Full article...) -
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Arthur Aikin FLS FGS (19 May 1773 – 15 April 1854) was an English chemist, mineralogist and scientific writer, and was a founding member of the Chemical Society (now the Royal Society of Chemistry). He first became its treasurer in 1841, and later became the society's second president. (Full article...) -
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Frederick Augustus Ludwig Karl Wilhelm Genth (May 17, 1820 – February 2, 1893) was a German-American chemist, specializing in analytical chemistry and mineralogy. (Full article...) -
Image 9Adolf 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...) -
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Alexander Petrovich Karpinsky (Russian: Александр Петрович Карпинский, trl. Aljeksandr Pjetrovič Karpinskij; 7 January 1847 [O.S. 26 December 1846] – 15 July 1936) was a prominent Russian and Soviet geologist and mineralogist, and the president of the Russian Academy of Sciences, and later Academy of Sciences of the USSR, in 1917–1936. (Full article...) -
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Torbern Olof Bergman (KVO) (20 March 1735 – 8 July 1784) was a Swedish chemist and mineralogist noted for his 1775 Dissertation on Elective Attractions, containing the largest chemical affinity tables ever published. Bergman was the first chemist to use the A, B, C, etc., system of notation for chemical species. (Full article...) -
Image 12Friedrich August Frenzel (24 May 1842 – 27 August 1902) was a German mineralogist. He was born in a miner's family in Freiberg, Saxony. In 1861 he was awarded a scholarship which enabled him to study mineralogy at Bergakademie Freiberg. There he attracted the attention of August Breithaupt who asked him to help with organising the mineralogical collections of the academy and with testing mineral samples, and to assist in the professor's mineralogical research. In 1865 Frenzel finished his studies and was awarded the title of a mining inspector. From then on, he worked for 25 years as a chemist in the metallurgical laboratories. He also lectured at the Bergakademie.
One of his best known works is the mineralogical encyclopedia for the Kingdom of Saxony (Mineralogisches Lexicon Für Das Königreich Sachsen), which contains descriptions of 723 minerals found in Saxony, information on their physical properties and chemical compositions, and descriptions of the corresponding localities. (Full article...) -
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Ours-Pierre-Armand Petit-Dufrénoy (5 September 1792 – 20 March 1857) was a French geologist and mineralogist. (Full article...) -
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George Washington Carpenter (July 31, 1802 – June 7, 1860) was an American scientist. (Full article...) -
Image 15Johannes Otto Conrad Mügge (4 March 1858, Hannover – 9 June 1932, Göttingen) was a German mineralogist and crystallographer.
From 1875 to 1879 he studied mathematics and sciences at the Technical University of Hannover and at the University of Göttingen. After graduation, he spent three years as an assistant to Harry Rosenbusch at the mineralogical-geological institute of the University of Heidelberg. From 1882 he worked as curator of the mineralogical and geological department at the Natural History Museum in Hamburg, and in 1886 became an associate professor at the academy in Münster. Later on, he served as a full professor at the University of Königsberg, where in 1903/04 he was named dean to the faculty of philosophy. In 1908 he relocated as a professor to the University of Göttingen. (Full article...) -
Image 16William James Lewis F.R.S. (10 January 1847 – 16 April 1926) was a Welsh mineralogist. (Full article...)
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Alfred Wilhelm Stelzner (20 December 1840, Dresden – 25 February 1895, Wiesbaden) was a German geologist.
From 1859 to 1864 he was a student at the Bergakademie Freiberg, an institute where he later served as inspector. From 1871 to 1874 he was a professor of mineralogy and geology at the University of Córdoba in Argentina. In 1874 he returned to the Bergakademie at Freiberg, where he succeeded his former teacher, Bernhard von Cotta. Here, he taught classes until his death in 1895. (Full article...) -
Image 18Maynard Bixby (June 28, 1853 – February 18, 1935) was an American mineralogist and mineral collector. (Full article...)
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Image 19Enrico Clerici (15 October 1862 – 26 August 1938) was an Italian mineralogist and geologist. From 1903 on he worked at the University of Rome. He published in 1907 the composition of a solution with a density of 4.25 g/cm3 at 20 °C, to determine the density of minerals. The Clerici solution is a mixture of thallium formate (Tl(CHO2)) and thallium malonate (Tl(C3H3O4)) in water. (Full article...)
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Theodor Liebisch (29 April 1852, Breslau – 9 February 1922, Berlin) was a German mineralogist and crystallographer. (Full article...) -
Image 21
Paul Niggli (26 June 1888 – 13 January 1953) was a Swiss crystallographer, mineralogist, and petrologist who was a leader in the field of X-ray crystallography. (Full article...) -
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Emil Wilhelm Cohen (12 October 1842 – 13 April 1905) was a German mineralogist and petrographer, born in Jutland. (Full article...) -
Image 23Walter Frederick Ferrier (1865–1950) was a Canadian geologist and mining engineer.
He graduated from McGill University's school of mining engineering. He was a tireless mineral collector and was known for walking straight into mining offices to request specimens. Consequently, he created large collections of mineral specimens of a quality still admired to this day. Many classic specimens would never be in collections had it not been for his effort and skill.
The mineral specimens he amassed were instrumental in creating the mineral collections of the Smithsonian in Washington DC, the Royal Ontario Museum in Toronto, Ontario, Canada, University of Alberta, and the museum particularly dear to his heart, the Redpath Museum at McGill University in Montreal, Quebec, Canada. (Full article...) -
Image 24
Friedrich Johann Karl Becke (31 December 1855, in Prague – 18 June 1931, in Vienna) was an Austrian mineralogist and petrographer. (Full article...) -
Image 25
William Gregor (25 December 1761 – 11 June 1817) was a British clergyman and mineralogist who discovered the elemental metal titanium. (Full article...)
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General images
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Image 2When 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 3Black andradite, an end-member of the orthosilicate garnet group. (from Mineral)
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Image 5Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). (from Mineral)
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Image 6Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background (from Mineral)
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Image 7Schist 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 8Native 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 11Red cinnabar (HgS), a mercury ore, on dolomite. (from Mineral)
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Image 14Gypsum desert rose (from Mineral)
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Image 15Diamond is the hardest natural material, and has a Mohs hardness of 10. (from Mineral)
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Image 18Sphalerite crystal partially encased in calcite from the Devonian Milwaukee Formation of Wisconsin (from Mineral)
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Image 19Epidote often has a distinctive pistachio-green colour. (from Mineral)
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Image 20An example of elbaite, a species of tourmaline, with distinctive colour banding. (from Mineral)
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Image 21Pink 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 22Mohs Scale versus Absolute Hardness (from Mineral)
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Image 23Asbestiform tremolite, part of the amphibole group in the inosilicate subclass (from Mineral)
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Image 24Muscovite, a mineral species in the mica group, within the phyllosilicate subclass (from Mineral)
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Image 26Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale (from Mohs scale)
Did you know ...?
- ... that the Lewisian gneiss (pictured), forms the basement to Torridonian and Cambro-Ordovician sedimentary rocks in the Hebridean Terrane?
- ... that abernathyite is both fluorescent and radioactive and is named for the mine operator who discovered it?
- ... that the minerals armalcolite, pyroxferroite and tranquillityite were discovered in lunar rocks?
- ...that the streak of a mineral, the color of the mark it makes when rubbed on a plate, is usually a more consistent identifier than the color of the original mineral?
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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