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Nahcolite
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A monoclinic mineral, NaHCO3 ; forms small, white, highly soluble, prismatic crystals; in nonmarine evaporite deposits; esp. abundant in parts of the Green River lake beds of Colorado.
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Niobium
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A shiny, white, soft, and ductile metallic element. Symbol, Nb (niobium) or Cb (columbium). The name niobium was adopted by the International Union of Pure and Applied Chemistry. Many chemical societies and government organizations refer to it as niobium, but most metallurgists, metals societies, and commercial producers still refer to the metal as columbium. Found in niobite (or columbite), niobite-tantalite, pyrochlore, and euxenite. Used as an alloying agent in carbon and alloy steels, in nonferrous metals, and in superconductive magnets. Syn: columbium
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Nacreous
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Adj. Applied to the luster of certain minerals, usually on crystal faces parallel to a good cleavage, the luster resembling that of pearls
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Nystagmus
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An eye disease suffered by some miners, in which there is a spasmodic oscillatory movement of the eyeballs; in severe cases, the victim finds difficulty in walking straight. Bad lighting is generally believed to be the main cause, and is possibly aggravated by the workers lying on their sides in thin seams
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Nystagmus
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An eye disease suffered by some miners, in which there is a spasmodic oscillatory movement of the eyeballs; in severe cases, the victim finds difficulty in walking straight. Bad lighting is generally believed to be the main cause, and is possibly aggravated by the workers lying on their sides in thin seams.
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Nadorite
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An orthorhombic mineral, PbSbO2 Cl ; an uncommon secondary mineral; in resinous to adamantine crystals in some base-metal deposits.
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Neomineralization
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Chemical interchange within a rock whereby its mineral constituents are converted into new mineral species; a type of recrystallization.
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Natural Slope
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The maximum angle at which loose material in a bank or spoil heap will stand without slipping.
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Nephelinitoid
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A nepheline-rich groundmass in an igneous rock; the glassy groundmass in nepheline rocks.
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Nablock
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A rounded mass, as of flint in chalk, or of ironstone in coal.
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