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olivine
olivine , an iron-magnesium silicate mineral, (Mg,Fe) 2 SiO 4 , crystallizing in the orthorhombic system. It is a common constituent of magnesium-rich, silica-poor igneous rocks; metamorphism of some high magnesium sediments also can form olivine. Dunite consists almost entirely of olivine. It also ...
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magnesite
magnesite , mineral, magnesium carbonate, MgCO 3 , white, yellow, or gray in color. It originates through the alteration of olivine or of serpentine by waters carrying carbon dioxide; through the replacement of calcium by magnesium in calcareous rocks, sometimes limestone but more often dolomite; an...
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kimberlite
kimberlite A brecciated (see BRECCIA), potassic, ultrabasic igneous rock, consisting of megacrysts of olivine, enstatite, Cr-rich diopside, phlogopite, pyropealmandine garnet, and Mg-rich ilmenite, in a fine-grained groundmass of serpentine, phlogopite, carbonates, perovskite, and chlorite, in varyi...
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serpentine
serpentine , hydrous silicate of magnesium. It occurs in crystalline form only as a pseudomorph having the form of some other mineral and is generally found in the form of chrysotile (silky fibers) and antigorite and lizardite (which are both tabular). Chrysotile is also known as commercial asbesto...
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basalt
basalt , fine-grained rock of volcanic origin, dark gray, dark green, brown, reddish, or black in color. Basalt is an igneous rock, i.e., one that has congealed from a molten state. Basaltic magma is derived by partial melting of the peridotite that is found in the asthenosphere which reaches th...
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garnet
garnet name applied to a group of isomorphic minerals crystallizing in the cubic system. They are used chiefly as gems and as abrasives (as in garnet paper). The garnets are double silicates; one of the metallic elements is calcium, magnesium, ferrous iron, or manganese and the other aluminum, ferr...
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sand
sand rock material occurring in the form of loose, rounded or angular grains, varying in size from .06 mm to 2 mm in diameter, the particles being smaller than those of gravel and larger than those of silt or clay . Sand is formed as a result of the weathering and decomposition of igneous, s...
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gem
gem commonly, a mineral or organic substance, cut and polished and used as an ornament. Gems also are used as seals (items of assurance) and as talismans (good-luck charms). For birthstones, see month .
Properties of Gems
The qualities sought in gems are beauty, rarity, and durability. T...
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North Carolina
North Carolina state in the SE United States. It is bordered by the Atlantic Ocean (E), South Carolina and Georgia (S), Tennessee (W), and Virginia (N).
Facts and Figures
Area, 52,586 sq mi (136,198 sq km). Pop. (2000) 8,049,313, a 21.4% increase since the 1990 census. Capital, Rale...
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gold rush
gold rush influx of prospectors, merchants, adventurers, and others to newly discovered gold fields. One of the most famous of these stampedes in pursuit of riches was the California gold rush. The discovery of gold at Sutter's Mill early in 1848 brought more than 40,000 prospectors to California w...
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