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...)
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.
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.
Apatite (CaF) (fluorapatite) doubly-terminated crystal in calcite
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 geologistAbraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogistKarl 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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A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm.
Andesite is the extrusive equivalent of plutonicdiorite. 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.
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...)
Ruby is a pinkish red to blood-red colored gemstone, a variety of the mineralcorundum (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 rutileinclusions 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, which sold for US$34.8 million. (Full article...)
The term was originally coined in 1756 by SwedishmineralogistAxel 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 Greekζέω (zéō), meaning "to boil" and λίθος (líthos), meaning "stone".
Zeolites occur naturally, but are also produced industrially on a large scale. As of December 2018[update], 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...)
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...)
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...)
Amethyst is a violet variety of quartz. The name comes from the Koine Greekαμέθυστοςamethystos from α-a-, "not" and μεθύσκω (Ancient Greek) methysko / μεθώmetho (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.
Micas (/ˈmaɪkəz/MY-kəz) are a group of silicateminerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile 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, and fillers, especially in parts for automobiles, roofing, and in electronics. The mineral is used in cosmetics and food to add "shimmer" or "frost". (Full article...)
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Green fluorite with prominent cleavage 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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The diamond crystal structure belongs to the face-centered cubic lattice, with a repeated two-atom pattern. 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.
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...)
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.
The name derives from the Persianzargun, 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...)
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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Graphite specimen
Graphite (/ˈɡræfaɪt/) is a crystalline allotrope (form) of the element carbon. It consists of many stacked layers of graphene, typically in the excess of hundreds 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. Graphite's low cost, thermal and chemical inertness and characteristic conductivity of heat and electricity finds numerous applications in high energy and high temperature processes. (Full article...)
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...)
The Mohs scale of mineral hardness, based on scratchhardness 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.
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...)
An examination of White's career reveals steady progression from an initial technical focus on the goldfields of Western Australia, to the challenge of new mining enterprises in Fiji, to post-war rehabilitation of tin mining in Malaya, ultimately to encompass a broad appreciation of the complexities of the minerals industry as a whole, its human factors, and societal context. He applied these insights in developing innovative academic programs at the University of Queensland and at McGill University, referring to the spectrum as "the total environment of mining". To pursue this vision at McGill, in 1968 he initiated an Institute for Mineral Industry Research. Two buildings, including a geodesic dome, were constructed to house the institute at the mineral-rich Gault Estate in Mont-Saint-Hilaire, Quebec, where ventilation research and simulations were conducted. This initiative came to an end due to his untimely death; his ashes were scattered at the site, and a commemorative cairn erected. Momentum from the initiative contributed to the formation in 1974 of an Institute of Occupational Health and Safety at McGill. A monument in his honor, donated by former students, is in place at the Experimental Mine, University of Queensland. His life story is the subject of a biography entitled Miner with a Heart of Gold. (Full article...)
He was one of the most important mentors of Brazilian independence, and his actions were decisive for the success of Emperor Pedro I. He supported public education, was an abolitionist and suggested that a new national capital be created in Brazil's underdeveloped interior (effected over a century later as Brasília). His career as naturalist was marked by the discovery of four new minerals. (Full article...)
Luca Bindi (born 1971) is an Italian geologist. He holds the Chair of Mineralogy and Crystallography and is the Head of the Department of Earth Sciences of the University of Florence. He is also a research associate at the Istituto di Geoscienze e Georisorse of the National Research Council (Italy) (CNR). He has received national and international scientific awards that include the President of the Republic Prize 2015 in the category of Physical, Mathematical and Natural Sciences. Since 2019 is a Member of the National Academy of Lincei.
He is the Italian scientist who has contributed to the description of the highest number of new minerals and is among the top ten researchers in the world for the number of new mineralogical species described. In his career he has described about 2% of the 6,000 minerals known in nature. Most of the new materials were discovered in the precious patrimony of the collections of the Museum System of the Florentine University, with its approximately fifty thousand specimens. The researcher is entitled to a further record: among the 150 minerals he described there are 15 extraterrestrials (almost 3% of the 500 discovered), identified in meteorite fragments. (Full article...)
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...)
Alexandra Navrotsky with Lee Penn performing the methane mamba chemical demonstration
Alexandra Navrotsky (born 20 June 1943 in New York City) is a physical chemist in the field of nanogeoscience. She is an elected member of the United States National Academy of Sciences (NAS) and the American Philosophical Society (APS). She was a board member of the Earth Sciences and Resources division of the NAS from 1995 until 2000. In 2005, she was awarded the Urey Medal, by the European Association of Geochemistry. In 2006, she was awarded the Harry H. Hess Medal, by the American Geophysical Union. She is currently the director of NEAT ORU (Nanomaterials in Environment, Agriculture, and Technology Organized Research Unit), a primary program in nanogeoscience. She is distinguished professor at University of California, Davis. (Full article...)
Born in the Grand Duchy of Finland in the Russian Empire, he was forced to move to Sweden in 1857 due to his political activity, where he became a member of the Parliament of Sweden and of the Swedish Academy. He led the Vega Expedition along the northern coast of Eurasia in 1878–1879. This was the first complete crossing of the Northeast Passage. Initially a troubled enterprise, the successful expedition is considered to be among the highest achievements in the history of Swedish science. (Full article...)
After finishing his studies at the gymnasium of Kreuznach in 1859 Lossen became a mining engineer; he began by two and a half years of practical work, then studied at the Universities of Berlin and Halle, where he graduated in 1866; in the same year he became assistant geologist of the Prussian national geological survey. He began immediately his well-known petrolographic studies of the Harz Mountains, which lasted till his death. In 1870 he became instructor in petrology at the Berlin mining academy, and at the same time lecturer at the university. In 1873, he was made a member of the newly founded Prussian National Geological Institute, and in 1882 received the title of professor; he was a fellow of the Görres Society from its foundation. In 1886, he became an associate professor in the university. (Full article...)
Image 8Pink 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)
Image 9Diamond is the hardest natural material, and has a Mohs hardness of 10. (from Mineral)
Image 10Topaz has a characteristic orthorhombic elongated crystal shape. (from Mineral)
Image 13Galena, PbS, is a mineral with a high specific gravity. (from Mineral)
Image 14When 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)
Image 15Black andradite, an end-member of the orthosilicate garnet group. (from Mineral)
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Paul Ramdohr as a member of student fraternity Leonensia in Heidelberg (1909)
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Muscovite, a mineral species in the mica group, within the phyllosilicate subclass (from Mineral)
Gypsum desert rose (from Mineral)
Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background (from Mineral)
Pyrite (from Lustre (mineralogy))
Pink 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)
Diamond is the hardest natural material, and has a Mohs hardness of 10. (from Mineral)
Sphalerite crystal partially encased in calcite from the Devonian Milwaukee Formation of Wisconsin (from Mineral)
When 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)
Black andradite, an end-member of the orthosilicate garnet group. (from Mineral)
Schist 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)
Mohs hardness kit, containing one specimen of each mineral on the ten-point hardness scale (from Mohs scale)
Mohs Scale versus Absolute Hardness (from Mineral)
Native 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)
Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). (from Mineral)
Epidote often has a distinctive pistachio-green colour. (from Mineral)
Red cinnabar (HgS), a mercury ore, on dolomite. (from Mineral)
An example of elbaite, a species of tourmaline, with distinctive colour banding. (from Mineral)
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