1.
Mantle (geology)
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The mantle is a layer inside a terrestrial planet and some other rocky planetary bodies. For a mantle to form, the body must be large enough to have undergone the process of planetary differentiation by density. The mantle surrounds the planetary core, the mantle is surrounded by the crust. The terrestrial planets, the Moon, two of Jupiters moons and the asteroid Vesta each have a made of silicate rock. Interpretation of spacecraft data suggests that at least two moons of Jupiter, as well as Titan and Triton each have a mantle made of ice or other solid volatile substances. The interior of Earth, similar to the terrestrial planets, is divided into layers of different composition. The mantle is a layer between the crust and the outer core, Earths mantle is a silicate rocky shell with an average thickness of 2,886 kilometres. The mantle makes up about 84% of Earths volume and it is predominantly solid but in geological time it behaves as a very viscous fluid. The mantle encloses the hot core rich in iron and nickel, past episodes of melting and volcanism at the shallower levels of the mantle have produced a thin crust of crystallized melt products near the surface. A thin crust, the part of the lithosphere, surrounds the mantle and is about 5 to 75 km thick. In some places under the ocean the mantle is exposed on the surface of Earth. The mantle is divided into sections which are based upon results from seismology and these layers are the following, the upper mantle, the transition zone, the lower mantle, and anomalous core–mantle boundary with a variable thickness. The uppermost mantle plus overlying crust are relatively rigid and form the lithosphere, below the lithosphere the upper mantle becomes notably more plastic. In some regions below the lithosphere, the shear velocity is reduced. Inge Lehmann discovered a seismic discontinuity at about 220 km depth, although this discontinuity has been found in other studies, the transition zone is an area of great complexity, it physically separates the upper and lower mantle. Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous, the D layer at the core–mantle boundary separates the mantle from the core. A principal source of the heat that drives plate tectonics is the decay of uranium, thorium. The mantle differs substantially from the crust in its properties as the direct consequence of the difference in composition
2.
Volcanic rock
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Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin, for these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term volcanic is often applied to what are strictly metavolcanic rocks, Volcanic rocks are among the most common rock types on Earths surface, particularly in the oceans. On land, they are common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earths current land surface, lava Tephra Volcanic bomb Lapilli Volcanic ash Volcanic rocks are usually fine-grained or aphanitic to glass in texture. They often contain clasts of other rocks and phenocrysts, phenocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a fine grained matrix. Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava, pumice is a highly vesicular rock produced in explosive volcanic eruptions. Most modern petrologists classify igneous rocks, including rocks, by their chemistry when dealing with their origin. The fact that different mineralogies and textures may be developed from the same initial magmas has led petrologists to rely heavily on chemistry to look at a volcanic rocks origin. The chemistry of volcanic rocks is dependent on two things, the composition of the primary magma and the subsequent differentiation. Differentiation of most volcanic rocks tends to increase the silica content, the initial composition of most volcanic rocks is basaltic, albeit small differences in initial compositions may result in multiple differentiation series. The most common of these series are tholeiitic, calc-alkaline, most volcanic rocks share a number of common minerals. Differentiation of volcanic rocks tends to increase the silica content mainly by fractional crystallization, thus, more evolved volcanic rocks tend to be richer in minerals with a higher amount if silica such as phyllo and tectosilicates including the feldspars, quartz polymorphs and muscovite. While still dominated by silicates, more volcanic rocks have mineral assemblages with less silica, such as olivine. Bowens reaction series correctly predicts the order of formation of the most common minerals in volcanic rocks, occasionally, a magma may pick up crystals that crystallized from another magma, these crystals are called xenocrysts. Diamonds found in kimberlites are rare but well-known xenocrysts, the kimberlites do not create the diamonds, Volcanic rocks are named according to both their chemical composition and texture. Basalt is a common volcanic rock with low silica content
3.
Calcium oxide
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Calcium oxide, commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature, the broadly used term lime connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, quicklime specifically applies to the chemical compound calcium oxide. Calcium oxide that survives processing without reacting in building such as cement is called free lime. Both it and a chemical derivative are important commodity chemicals, Calcium oxide is usually made by the thermal decomposition of materials, such as limestone or seashells, that contain calcium carbonate in a lime kiln. This is accomplished by heating the material to above 825 °C, annual worldwide production of quicklime is around 283 million tonnes. China is by far the worlds largest producer, with a total of around 170 million tonnes per year, the United States is the next largest, with around 20 million tonnes per year. Approximately 1.8 t of limestone is required per 1.0 t of quicklime, quicklime has a high affinity for water and is a more efficient desiccant than silica gel. The reaction of quicklime with water is associated with an increase in volume by a factor of at least 2.5, the major use of quicklime is in the Basic oxygen steelmaking process. Its usage varies from about 30–50 kg/t of steel, the quicklime neutralizes the acidic oxides, SiO2, Al2O3, and Fe2O3, to produce a basic molten slag. Ground quicklime is used in the production of aerated concrete blocks, quicklime and hydrated lime can considerably increase the load carrying capacity of clay-containing soils. They do this by reacting with finely divided silica and alumina to produce calcium silicates and aluminates, small quantities of quicklime are used in other processes, e. g. the production of glass, calcium aluminate cement, and organic chemicals. The hydrate can be reconverted to quicklime by removing the water by heating it to redness to reverse the hydration reaction, one litre of water combines with approximately 3.1 kilograms of quicklime to give calcium hydroxide plus 3.54 MJ of energy. This process can be used to provide a convenient portable source of heat, light, When quicklime is heated to 2,400 °C, it emits an intense glow. This form of illumination is known as a limelight, and was used broadly in theatrical productions prior to the invention of electric lighting, cement, Calcium oxide is a key ingredient for the process of making cement. As a cheap and widely available alkali, about 50% of the total quicklime production is converted to calcium hydroxide before use. Both quick- and hydrated lime are used in the treatment of drinking water, petroleum industry, Water detection pastes contain a mix of calcium oxide and phenolphthalein. Should this paste come into contact with water in a storage tank
4.
Aluminium oxide
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Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and it is commonly called alumina, and may also be called aloxide, aloxite, or alundum depending on particular forms or applications. It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of form the precious gemstones ruby. Al2O3 is significant in its use to produce metal, as an abrasive owing to its hardness. Corundum is the most common naturally occurring form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colors to trace impurities, rubies are given their characteristic deep red color and their laser qualities by traces of chromium. Sapphires come in different colors given by various other impurities, such as iron, Al2O3 is an electrical insulator but has a relatively high thermal conductivity for a ceramic material. Aluminium oxide is insoluble in water, in its most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools. Aluminium oxide is responsible for the resistance of aluminium to weathering. Metallic aluminium is very reactive with oxygen, and a thin passivation layer of aluminium oxide forms on any exposed aluminium surface. This layer protects the metal from further oxidation, the thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. Aluminium oxide was taken off the United States Environmental Protection Agencys chemicals lists in 1988, aluminium oxide is on EPAs Toxics Release Inventory list if it is a fibrous form. Al2O3 +6 HF →2 AlF3 +3 H2O Al2O3 +2 NaOH +3 H2O →2 NaAl4 The most common form of aluminium oxide is known as corundum. The oxygen ions form a hexagonal close-packed structure with aluminium ions filling two-thirds of the octahedral interstices. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a group of R-3c. The primitive cell contains two units of aluminium oxide. Each has a crystal structure and properties
5.
Sodium oxide
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Sodium oxide is a chemical compound with the formula Na2O. It is used in ceramics and glasses, though not in a raw form and it is the base anhydride of sodium hydroxide, so when water is added to sodium oxide NaOH is produced. Na2O + H2O →2 NaOH The alkali metal oxides M2O crystallise in the antifluorite structure, burning sodium in air will produce Na2O and about 20% sodium peroxide Na2O2. 6 Na +2 O2 →2 Na2O + Na2O2 Alternatively, sodium carbonate can be heated to 851 °C, producing carbon dioxide, na2CO3 → Na2O + CO2 At 208 °C, sodium ascorbate will decompose to furan derivatives and sodium oxide. Sodium oxide is a significant component of glasses and windows although it is added in the form of soda, Sodium oxide does not explicitly exist in glasses, since glasses are complex cross-linked polymers. Typically, manufactured glass contains around 15% sodium oxide, 70% silica, the sodium carbonate soda serves as a flux to lower the temperature at which the silica melts. Soda glass has a lower melting temperature than pure silica. These changes arise because the silicon dioxide and soda react to form sodium silicates of the general formula Na2x, na2CO3 → Na2O + CO2 Na2O + SiO2 → Na2SiO3 Sodium oxide information at Webelements
6.
Magnesium oxide
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Magnesium oxide, or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium. It has a formula of MgO and consists of a lattice of Mg2+ ions. Magnesium hydroxide forms in the presence of water, but it can be reversed by heating it to separate moisture, Magnesium oxide was historically known as magnesia alba, to differentiate it from magnesia negra, a black mineral containing what is now known as manganese. While magnesium oxide normally refers to MgO, magnesium peroxide MgO2 is also known as a compound, because of its stability, MgO is used as a model system for investigating vibrational properties of crystals. Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide, the latter is obtained by the treatment of magnesium chloride solutions, typically seawater, with lime. Mg2+ + Ca2 → Mg2 + Ca2+ Calcining at different temperatures produces magnesium oxide of different reactivity, high temperatures 1500 -2000 °C diminish the available surface area and produces dead-burned magnesia, an unreactive form used as a refractory. Although some decomposition of the carbonate to oxide occurs at temperatures below 700 °C, MgO is prized as a refractory material, i. e. a solid that is physically and chemically stable at high temperatures. It has two attributes, high thermal conductivity and low electrical conductivity. MgO is used as a refractory material for crucibles. It is a principal fireproofing ingredient in construction materials, as a construction material, magnesium oxide wallboards have several attractive characteristics, fire resistance, termite resistance, moisture resistance, mold and mildew resistance, and strength. MgO is one of the components in Portland cement in dry process plants, many heavy metals species, such as lead and cadmium are most soluble in water at acidic pH as well as high pH. Solubility of metals affects bioavailability of the species and mobility soil, most metal species are toxic to humans at certain concentrations, therefore it is imperative to minimize metal bioavailability and mobility. Metal-hydroxide complexes have a tendency to precipitate out of solution in the pH range of 8-10. Most, if not all products that are marketed as metals stabilization technologies create very high pH conditions in aquifers whereas MgO creates an ideal aquifer condition with a pH of 8-10. Additionally, magnesium, an element to most biological systems, is provided to soil. In medicine, magnesium oxide is used for relief of heartburn and sour stomach, as an antacid, magnesium supplement and it is also used to improve symptoms of indigestion. Side effects of magnesium oxide may include nausea and cramping, in quantities sufficient to obtain a laxative effect, side effects of long-term use include enteroliths resulting in bowel obstruction. It is used as a white color in colorimetry, owing to its good diffusing
7.
Kimberlite
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Kimberlite is an igneous rock best known for sometimes containing diamonds. Kimberlite occurs in the Earths crust in vertical structures known as kimberlite pipes as well as igneous dykes, Kimberlite also occurs as horizontal sills. Kimberlite pipes are the most important source of mined diamonds today, the consensus on kimberlites is that they are formed deep within the mantle. It is this depth of melting and generation which makes kimberlites prone to hosting diamond xenocrysts, despite its relative rarity, kimberlite has attracted attention because it serves as a carrier of diamonds and garnet peridotite mantle xenoliths to the Earths surface. Many kimberlite structures are emplaced as carrot-shaped, vertical intrusions termed pipes, Kimberlite classification is based on the recognition of differing rock facies. These differing facies are associated with a style of magmatic activity, namely crater, diatreme. The morphology of kimberlite pipes, and their classical carrot shape is the result of explosive volcanism from very deep mantle-derived sources. These volcanic explosions produce vertical columns of rock rise from deep magma reservoirs. The morphology of kimberlite pipes is varied but includes a sheeted dyke complex of tabular, within 1. 5–2 km of the surface, the highly pressured magma explodes upwards and expands to form a conical to cylindrical diatreme, which erupts to the surface. The surface expression is rarely preserved but is similar to a maar volcano. The diameter of a pipe at the surface is typically a few hundred meters to a kilometer. Two Jurassic kimberlite dikes exist in Pennsylvania, one, the Gates-Adah Dike, outcrops on the Monongahela River on the border of Fayette and Greene Counties. The other, the Dixonville-Tanoma Dike in central Indiana County, does not outcrop at the surface and was discovered by miners, similarly aged kimberlite is found in several locations in New York Both the location and origin of kimberlitic magmas are subjects of contention. The mechanism of enrichment has also been the topic of interest with models including partial melting, historically, kimberlites have been classified into two distinct varieties termed basaltic and micaceous based primarily on petrographic observations. This was later revised by Smith who renamed these divisions Group I and Group II based on the affinities of these rocks using the Nd, Sr. Mitchell later proposed that these group I and II kimberlites display such distinct differences and he showed that Group II kimberlites show closer affinities to lamproites than they do to Group I kimberlites. Hence, he reclassified Group II kimberlites as orangeites to prevent confusion, olivine lamproites were previously called Group II kimberlite or orangeite in response to the mistaken belief that they only occurred in South Africa. Their occurrence and petrology, however, are identical globally and should not be referred to as kimberlite
