Physics

Rhenium

Rhenium

Rhenium Definition Rhenium is a very rare, dense, silvery-white metallic element with a very high melting point. It is used to make catalysts and electrical contacts. Its atomic number 75; atomic weight 186.2; melting point 3,180°C; boiling point 5,627°C; specific gravity 21.02; valence 1, 2, 3.....

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Diorite

Diorite

Diorite Definition Diorite is a gray, coarse-grained plutonic rock. Diorite consists mainly of sodium-rich plagioclase and one or more mafic minerals such as biotite, hornblende, or pyroxene. It is the coarse-grained equivalent of andesite. Diorite may contain small amounts of quartz, microcline,.....

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Monzonite

Monzonite

Monzonite Definition Monzonite is an igneous rock composed chiefly of plagioclase and orthoclase, with small amounts of amphibole, pyroxene, and biotite. Monzonite contains little or no quartz. The rocks are of granitic appearance, usually rather dark grey in colour and fine to moderately coarse .....

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Syenite

Syenite

Syenite Definition Syenite is a light-colored, coarse-grained igneous rock consisting primarily of alkali feldspar together with some mafic minerals, especially hornblende. Unlike most igneous rocks, syenite has little or no quartz. Some syenites contain larger proportions of mafic components and.....

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Chondrite

Chondrite

Chondrite Definition Chondrite is a stony meteorite that contains chondrules embedded in a fine matrix of the silicate minerals olivine and pyroxene. About 85 percent of all meteorites are chondrites. One of their characteristics is the presence of chondrules, which are round grains formed by dis.....

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Meteorite

Meteorite

Meteorite Definition Meteorite is a meteor that reaches the Earth’s surface because it has not been burned up by friction with the atmosphere. Meteorites are believed to be fragments of comets and asteroids. Meteorites are pieces of other bodies in our solar system that make it to the groun.....

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Cryolite

Cryolite

Cryolite Definition Cryolite is a white or colourless mineral consisting of a fluoride of sodium and aluminium in monoclinic crystalline form: used in the production of aluminium, glass, and enamel. It was first described in 1798 by Danish veterinarian and physician Peder Christian Abildgaard (17.....

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Fluorite

Fluorite

Fluorite Definition Fluorite (CaF2) is a transparent to translucent mineral occurring in many colors, especially yellow and purple, and usually in cube-shaped crystals with octahedral cleavage. It is also called fluorspar. It is found in sedimentary rocks and in ore deposits within igneous rocks......

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Pyrite

Pyrite

Pyrite Definition Pyrite (FeS2) is a silver to yellow, metallic, cubic mineral. Pyrite often crystallizes in cubes or octahedrons but also occurs as shapeless masses of grains. It occurs in most types of rocks, and is used as a source of iron and in making sulfur dioxide. It is a polymorph of mar.....

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Tantalum

Tantalum

Tantalum Definition Tantalum is a hard, heavy, gray metallic element that is highly resistant to corrosion at low temperatures. It is almost immune to chemical attack at temperatures below 150o C. Tantalum is virtually resistant to corrosion due to an oxide film on its surface. Its atomic number .....

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Pyrochlore

Pyrochlore

Pyrochlore Definition Pyrochlore is a complex oxide mineral (Na,Ca)2Nb2O6(OH,F), which is composed of niobium, sodium, and calcium that forms brown to black, glassy octahedral crystals and irregular masses. Pyrochlore crystallizes in the isometric symmetry class and forms fine octahedral crystals.....

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Niobium

Niobium

Niobium Definition Niobium is a soft, silvery, ductile metallic element that usually occurs in nature together with the element tantalum. It is used to build nuclear reactors, to make steel alloys, and to allow magnets to conduct electricity with almost no resistance. Atomic number 41; atomic wei.....

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