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Allophane
Allophane is an amorphous to poorly crystalline hydrous aluminium silicate clay mineraloid. Its chemical formula is Al2O3·(SiO2)1.3-2·(2.5-3)H2O. Since it has short-range atomic order, it is a mineraloid, rather than a mineral, and can be identified by its distinctive infrared spectrum and its X-ray diffraction pattern. It was first described in 1816 in Gräfenthal, Thuringia, Germany. Allophane is a weathering or hydrothermal alteration product of volcanic glass and feldspars and sometimes has a composition similar to kaolinite but generally has a molar ratio of Al:Si = 2. It typically forms under mildly acidic to neutral pH (5–7). Its structure has been debated, but it is similar to clay minerals and is composed of curved alumina octahedral and silica tetrahedral layers.Smalley, I.J. 1979. A spherical structure for allophane. Nature 281, 339 only Transmission electron micrographs show that it is generally made up of aggregates of hollow spherules ~3–5 nm in diameter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaolinite
Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral sheet of alumina (). 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 () 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 app ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllosilicates
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dioxide, ) are usually considered to be Silicate mineral#Tectosilicates, tectosilicates, and they are classified as such in the Dana system (75.1). However, the Nickel-Strunz system classifies them as oxide minerals (4.DA). Silica is found in nature as the mineral quartz, and its polymorphism (materials science), polymorphs. On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis. Living organisms also contribute to this carbonate–silicate cycle, geologic cycle. For example, a type of plankton ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Glass
Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass, it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disordered array of liquid. Volcanic glass may refer to the interstitial material, or matrix, in an aphanitic (fine-grained) volcanic rock, or to any of several types of vitreous igneous rocks. Origin Volcanic glass is formed when magma is rapidly cooled. Magma rapidly cooled to below its normal crystallization temperature becomes a supercooled liquid, and, with further rapid cooling, this becomes an amorphous solid. The change from supercooled liquid to glass occurs at a temperature called the glass transition temperature, which depends on both cooling rate and the amount of water dissolved in the magma. Magma rich in silica and poor in dissolved water is most easily cooled rapidly enough to form volcanic glass. As a result, rhyolite magmas, which are high in si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blowpipe (tool)
A blowpipe is one of several tools used to direct streams of gases into any of several working media. Blowpipes for torches If a stream or jet of air is directed through a flame, fuel air mixing is enhanced and the jet exiting the flame is intensely hot. Jewelers and glassblowers engaged in lampwork have used the blowpipe since ancient times, with the blast being powered by the user's lungs. For small work, a mouth-blown blowpipe may be used with a candle flame or an alcohol lamp, with established techniques for applying oxidizing and reducing flames to the workpiece or specimen. Starting in the late 18th Century, blowpipes have been powered by mechanisms, initially bladders and bellows, but now blowers, compressors and compressed gas cylinders are commonplace. While blowing air is effective, blowing oxygen produces higher temperatures, and it is also practical to invert the roles of the gasses and blow fuel through air. Contemporary blowtorches and oxy-fuel welding and cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Language
Greek (, ; , ) is an Indo-European languages, Indo-European language, constituting an independent Hellenic languages, Hellenic branch within the Indo-European language family. It is native to Greece, Cyprus, Italy (in Calabria and Salento), southern Albania, and other regions of the Balkans, Caucasus, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the list of languages by first written accounts, longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting importance in the European canon. Greek is also the language in which many of the foundational texts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Gravity
Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nearly always measured with respect to water at its densest (at ); for gases, the reference is air at room temperature (). The term "relative density" (abbreviated r.d. or RD) is preferred in SI, whereas the term "specific gravity" is gradually being abandoned. If a substance's relative density is less than 1 then it is less dense than the reference; if greater than 1 then it is denser than the reference. If the relative density is exactly 1 then the densities are equal; that is, equal volumes of the two substances have the same mass. If the reference material is water, then a substance with a relative density (or specific gravity) less than 1 will float in water. For example, an ice cube, with a relative density of about 0.91, will float. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mohs Hardness
The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral 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.John P. Rafferty, ed. (2011): Mi ...s through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the German geologist and Mineralogy, mineralogist Friedrich Mohs, in his book (English: Attempt at an elementary method for the natural-historical determination and recognition of fossils); it is one of several definitions of hardness comparison, hardness in materials science, some of which are more quantitative. The method of comparing hardness by observing which minerals can scratch others is of great antiquity, having been mentioned by Theophrastus in his treatise ''On Stones'', , followed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gibbsite
Gibbsite, Al(OH)3, is one of the mineral forms of aluminium hydroxide. It is often designated as γ-Al(OH)3 (but sometimes as α-Al(OH)3). It is also sometimes called hydrargillite (or hydrargyllite). Gibbsite is an important ore of aluminium in that it is one of three main phases that make up the rock bauxite. Gibbsite has three named structural polymorphs or polytypes: bayerite (designated often as α-Al(OH)3, but sometimes as β-Al(OH)3), '' doyleite'', and nordstrandite. Gibbsite can be monoclinic or triclinic, while bayerite is monoclinic. Doyleite and nordstrandite are triclinic forms. Structure The structure of gibbsite is interesting and analogous to the basic structure of the micas. The basic structure forms stacked sheets of linked octahedra. Each octahedron is composed of an aluminium ion bonded to six hydroxide groups, and each hydroxide group is shared by two aluminium octahedra. One third of the potential octahedral spaces are missing a central aluminiu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halloysite
Halloysite is an aluminosilicate clay mineral with the empirical formula Al2Si2O5(OH)4. Its main constituents are oxygen (55.78%), silicon (21.76%), aluminium (20.90%), and hydrogen (1.56%). It is a member of the kaolinite group. Halloysite typically forms by hydrothermal alteration of alumino-silicate minerals. It can occur intermixed with dickite, kaolinite, montmorillonite and other clay minerals. X-ray diffraction studies are required for positive identification. It was first described in 1826, and subsequently named after, the Belgian people, Belgian geologist Jean Baptiste Julien d'Omalius d'Halloy, Omalius d'Halloy. Structure Halloysite naturally occurs as small cylinders (nanotubes) that have a wall thickness of 10–15 atomic aluminosilicate sheets, an outer diameter of 50–60 nm, an inner diameter of 12–15 nm, and a length of 0.5–10 μm. Their outer surface is mostly composed of SiO2 and the inner surface of Al2O3, and hence those surfaces are opposit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay Mineral
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water and have been important to life, and many theories of abiogenesis involve them. They are important constituents of soils, and have been useful to humans since ancient times in agriculture and manufacturing. Properties Clay is a very fine-grained geologic material that develops plasticity when wet, but becomes hard, brittle and non–plastic upon drying or firing. It is a very common material, and is the oldest known ceramic. Prehistoric humans discovered the useful properties of clay and used it for making pottery. The chemistry of clay, including its capacity to retain nutrient cations such as potassium and ammonium, is important to soil fertility. Because the individual particles in clay are less ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feldspar
Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspars and the ''alkali'' (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight. Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rocks. Etymology The name ''feldspar'' derives from the German , a compound of the words ' ("field") and ("flake"). had long been used as the word for "a rock easily cleaved into flakes"; was introduced in the 18th century as a more specific term, referring perhaps to its comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
