Fluorite Lens
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, s ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Halide Mineral
Halide minerals are those minerals with a dominant halide anion (, , and ). Complex halide minerals may also have Polyatomic ion, polyatomic anions. Examples include the following: *Atacamite *Avogadrite (K,Cs)BF *Bararite (β) *Bischofite *Brüggenite *Calomel *Carnallite *Carnallite *Cerargyrite/Horn silver AgCl *Chlorargyrite AgCl, bromargyrite AgBr, and iodargyrite AgI *Cryolite *Cryptohalite (a) . *Dietzeite *Eglestonite *Embolite AgCl+AgBr *Eriochalcite *Fluorite *Halite NaCl *Lautarite *Marshite CuI *Miersite AgI *Nantokite CuCl *Sal Ammoniac *Sylvite KCl *Terlinguaite *Tolbachite *Villiaumite NaF *Yttrocerite (Ca,Y,Ce)F2 *Yttrofluorite (Ca,Y)F2 *Zavaritskite (BiO)F Many of these minerals are water-soluble and are often found in ar ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Scratch Hardness
Scratch hardness refers to the hardness of a material in terms of resistance to scratches and abrasion by a harder material forcefully drawn over its surface. Scratch hardness test or scratch test refers to any of a number of methods of measuring scratch hardness. Resistance to abrasion is less affected by surface variations than indentation methods. Scratch hardness is measured with a sclerometer. Attempting to scratch a surface to test a material is a very old technique. The first ''scientific'' attempt to quantify materials by scratch tests was by mineralogist Friedrich Mohs in 1812 (see Mohs scale)."Mohs hardness" in ''Encyclopædia Britannica Online'' The Mohs scale is based on relative scratch hardness of different materials; with [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Philology
Philology () is the study of language in Oral tradition, oral and writing, written historical sources. It is the intersection of textual criticism, literary criticism, history, and linguistics with strong ties to etymology. Philology is also defined as the study of literary texts and oral and written records, the establishment of their authentication, authenticity and their original form, and the determination of their meaning. A person who pursues this kind of study is known as a philologist. In older usage, especially British, philology is more general, covering comparative linguistics, comparative and historical linguistics. Classical philology studies classical languages. Classical philology principally originated from the Library of Pergamum and the Library of Alexandria around the fourth century BC, continued by Greeks and Romans throughout the Roman Empire, Roman and Byzantine Empire. It was eventually resumed by European scholars of the Renaissance humanism, Renaissance, ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Georgius Agricola
Georgius Agricola (; born Georg Bauer; 24 March 1494 – 21 November 1555) was a German Humanist scholar, mineralogist and metallurgist. Born in the small town of Glauchau, in the Electorate of Saxony of the Holy Roman Empire, he was broadly educated, but took a particular interest in the mining and refining of metals. He was the first to drop the Arabic definite article ''al-'', exclusively writing ''chymia'' and ''chymista'' in describing activity that we today would characterize as chemical or alchemical, giving chemistry its modern name. For his groundbreaking work '' De Natura Fossilium'' published in 1546, he is generally referred to as the father of mineralogy and the founder of geology as a scientific discipline.Rafferty, John P. (2012). ''Geological Sciences; Geology: Landforms, Minerals, and Rocks''. New York: Britannica Educational Publishing, p. 10. He is well known for his pioneering work '' De re metallica libri XII'', that was published in 1556, one yea ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Slag
The general term slag may be a by-product or co-product of smelting (pyrometallurgical) ores and recycled metals depending on the type of material being produced. Slag is mainly a mixture of metal oxides and silicon dioxide. Broadly, it can be classified as ferrous (co-products of processing iron and steel), ferroalloy (a by-product of ferroalloy production) or non-ferrous/ base metals (by-products of recovering non-ferrous materials like copper, nickel, zinc and phosphorus). Within these general categories, slags can be further categorized by their precursor and processing conditions (e.g., blast furnace slags, air-cooled blast furnace slag, granulated blast furnace slag, basic oxygen furnace slag, and electric arc furnace slag). Slag generated from the EAF process can contain toxic metals, which can be hazardous to human and environmental health. Due to the large demand for ferrous, ferralloy, and non-ferrous materials, slag production has increased throughout the years des ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (physics), stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Smelting
Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron-making, iron, copper extraction, copper, silver mining#Ore processing, silver, tin, lead smelting, lead and zinc smelting, zinc. Smelting uses heat and a chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving the metal behind. The reducing agent is commonly a fossil-fuel source of carbon, such as carbon monoxide from incomplete combustion of coke (fuel), coke—or, in earlier times, of charcoal. The oxygen in the ore binds to carbon at high temperatures, as the Chemical energy, chemical potential energy of the bonds in carbon dioxide () is lower than that of the bonds in the ore. Sulfide ores such as those commonly used to obtain copper, zinc or lead, are roasting (metallurgy), roasted before smelting in order to convert the sulfid ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area around Rome, Italy. Through the expansion of the Roman Republic, it became the dominant language in the Italian Peninsula and subsequently throughout the Roman Empire. It has greatly influenced many languages, Latin influence in English, including English, having contributed List of Latin words with English derivatives, many words to the English lexicon, particularly after the Christianity in Anglo-Saxon England, Christianization of the Anglo-Saxons and the Norman Conquest. Latin Root (linguistics), roots appear frequently in the technical vocabulary used by fields such as theology, List of Latin and Greek words commonly used in systematic names, the sciences, List of medical roots, suffixes and prefixes, medicine, and List of Latin legal terms ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Apochromat
An apochromat, or apochromatic lens (apo), is a photographic or other lens that has better correction of chromatic and spherical aberration than the much more common achromat lenses. The prefix ''apo-'' comes from the Greek preposition ''ἀπό-'', meaning free from or away from. Explanation Chromatic aberration is the phenomenon of different colors focusing at different distances from a lens. In photography, chromatic aberration produces soft overall images, and color fringing at high-contrast edges, like an edge between black and white. Astronomers face similar problems, particularly with telescopes that use lenses rather than mirrors. ''Achromatic'' lenses are corrected to bring ''two'' wavelengths into focus in the same plane – typically red (~0.590 μm) and blue (~0.495 μm). ''Apo''chromatic lenses are designed to bring ''three'' colors into focus in the same plane – typically red (~0.620 μm), green (~0.530 μm), and blue (~0.465 μ ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Dispersion (optics)
Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. Sometimes the term chromatic dispersion is used to refer to optics specifically, as opposed to wave propagation in general. A medium having this common property may be termed a dispersive medium. Although the term is used in the field of optics to describe light and other electromagnetic waves, dispersion in the same sense can apply to any sort of wave motion such as acoustic dispersion in the case of sound and seismic waves, and in gravity waves (ocean waves). Within optics, dispersion is a property of telecommunication signals along transmission lines (such as microwaves in coaxial cable) or the Pulse (signal processing), pulses of light in optical fiber. In optics, one important and familiar consequence of dispersion is the change in the angle of refraction of different colors of light, as seen in the spectrum produced by a dispersive Prism (optics), prism and in chromatic aberration ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Fine Chemical
In chemistry, fine chemicals are complex, single, pure chemical substances, produced in limited quantities in multipurpose plants by multistep batch chemical or biotechnological processes. They are described by exacting specifications, used for further processing within the chemical industry and sold for more than $10/kg (see the comparison of fine chemicals, commodities and specialties). The class of fine chemicals is subdivided either on the basis of the added value (building blocks, advanced intermediates or active ingredients), or the type of business transaction, namely standard or exclusive products. Fine chemicals are produced in limited volumes ( $10/kg) according to exacting specifications, mainly by traditional organic synthesis in multipurpose chemical plants. Biotechnical processes are gaining ground. Fine chemicals are used as starting materials for specialty chemicals, particularly pharmaceuticals, biopharmaceuticals and agrochemicals. Custom manufa ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Hydrofluoric Acid
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature. It is used to make most organofluorine compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers. Uses Production of organofluorine compounds The principal use of hydrofluoric acid is in organofluorine chemistry. Many organofluorine compounds are prepared using HF as the fluorine source, including Teflon, fluoropolymers, fluorocarbons, and refrigerants such as freon. Many pharmaceuticals contain fluorine. Production of inorganic fluorides Most high-volume inorganic fluoride compounds are prepared from hydrofluoric acid. Foremost ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |