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anglesite
anglesite , pale green, blue, yellow-to-white, or colorless mineral, a sulfate of lead, PbSO 4 , that is formed by oxidation of galena , crystallizing in the orthorhombic system and occurring also in granular or massive form. It is widely distributed and commonly associated with galena and other le...
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arsenopyrite
arsenopyrite or mispickel , silver-white to steel-gray mineral with the metallic luster characteristic of a pyrite . It is a sulfarsenide of iron, FeAsS, crystallizing in the orthorhombic system and occurring also in massive form. It is widely distributed and is an important source of arsenic. ...
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celestite
celestite or celestine , mineral appearing in blue-tinged or white orthorhombic crystals or in fibrous masses. The natural sulfate of strontium, SrSO 4 , it is important as a source of strontium and of certain of its compounds, e.g., strontium hydroxide, used in refining beet sugar, and strontiu...
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cerussite
cerussite , colorless to white or gray mineral, sometimes yellowish or greenish, transparent to opaque, very brittle, crystallizing in the orthorhombic system and occurring also in granular and massive form. It is a carbonate of lead, PbCO 3 , formed by the action of carbonate and bicarbonate soluti...
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marcasite
marcasite or white iron pyrites, a mineral closely resembling and having the same chemical composition (FeS 2 ) as pyrite . It differs from pyrite in that it is paler in color, becomes darker upon oxidation, and crystallizes in the orthorhombic system. Twinned crystals resembling cockscombs (c...
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stibnite
stibnite , antimony sulfide, Sb 2 S 3 , a mineral, silvery gray in color, with a metallic luster. It crystallizes in the orthorhombic system. Found in many parts of the world, it is the most important ore of antimony. It is commonly deposited by alkaline waters and occurs in association with quartz,...
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amphibole
amphibole , any of a group of widely distributed rock-forming minerals, magnesium-iron silicates, often with traces of calcium, aluminum, sodium, titanium, and other elements. The amphibole minerals are closely related in crystal structure, but they crystallize in two different systems, orthorhombic...
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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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pyroxene
pyroxene , name given to members of a group of widely distributed rock minerals called metasilicates in which magnesium, iron, and calcium, often with aluminum, sodium, lithium, manganese, or zinc occur as X in the chemical formula XSiO 3 . The pyroxene minerals crystallize in three different system...
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neptunium
neptunium , radioactive chemical element; symbol Np; at. no. 93; at. wt. 237.0482; m.p. about 640°C; b.p. 3,902°C (estimated); sp. gr. 20.25 at 20°C; valence +3, +4, +5, or +6. Neptunium is a ductile, silvery radioactive metal. It is a member of the actinide series in Group 3 of the p...
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