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quarrying
quarrying open, or surface, excavation of rock used for various purposes, including construction, ornamentation, road building, and as an industrial raw material. Rock that has been quarried is commonly called stone. Quarrying methods depend chiefly on the desired size and shape of the stone and it...
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mirror
mirror in optics, a reflecting surface that forms an image of an object when light rays coming from that object fall upon it (see reflection ). Usually mirrors are made of plate glass, one side of which is coated with metal or some special preparation to serve as a reflecting surface. The juncti...
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machine tool
machine tool power-operated tool used for finishing or shaping metal parts, especially parts of other machines. An establishment that is equipped with such tools and specializes in such work is known as a machine shop. Machine tools operate by removing material from the workpiece, much as a sculpto...
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clay
clay common name for a number of fine-grained, earthy materials that become plastic when wet. Chemically, clays are hydrous aluminum silicates, ordinarily containing impurities, e.g., potassium, sodium, calcium, magnesium, or iron, in small amounts.
Properties and Classification
Propertie...
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coal mining
coal mining physical extraction of coal resources to yield coal; also, the business of exploring for, developing, mining, and transporting coal in any form. Strip mining is the process in which the overburden (earth and rock material overlying the coal) is removed to expose a coal seam or coal bed....
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atrophy
atrophy , diminution in the size of a cell, tissue, or organ from its fully developed normal size. Temporary atrophy may occur in muscles that are not used, as when a limb is encased in a plaster cast. Interference with cellular nutrition, as through starvation; diseases affecting the nerve supply o...
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silt
silt predominantly quartz mineral particles that are between sand size and clay size, i.e., between 1/16 and 1/256 mm ( 1/406 - 1/6502 in.) in diameter. Silt, like clay and sand, is a product of the weathering and decomposition of preexisting rock. Hardened silt forms a sedimentary ro...
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drill
drill tool used to create a hole, usually in some hard substance, by its rotary or hammering action. Many different tools make up the drill family. The awl is a pointed instrument used for piercing small holes. In its early form it was a thorn or a tool of bone or chipped flint; many prehistoric aw...
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Bayard
Bayard , Ital. Baiardo , in chivalric romance, a bay horse, remarkable for his spirit and for his unique ability to fit his size to his rider. He appears in the 12th-century French epic Renaud de Montauban and in later tales of Roland by Boiardo, Ariosto, and Tasso.
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dung beetle
dung beetle Small to medium-sized scarab beetle. Some species form balls of dung as food for their larvae, and may roll the balls some distance before burying them. Family Scarabaeidae; species Geotrupus stercorarius....
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