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aragonite |
Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson | 0.06 sec. |
aragoniteA carbonate mineral, the stable form of calcium carbonate (CaCO3) at high pressures. It is somewhat harder and has a slightly higher specific gravity than calcite. Aragonite is found in recent deposits formed at low temperatures near the surface of the earth, as in caves as stalactites, with ore minerals, in serpentine and other basic (see acid and basic rocks) rocks, and in sediments. Aragonite is the mineral normally found in pearls, and it occurs in some animal shells. It is polymorphous (same chemical formula but different crystal structure) with calcite and vaterite, and, with geologic time, changes to calcite even under normal conditions. aragonite [ə′räg·ə‚nīt] (mineralogy) CaCO3A white, yellowish, or gray orthorhombic mineral species of calcium carbonate but with a crystal structure different from those of vaterite and calcite, the other two polymorphs of the same composition. Also known as Aragon spar. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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| In nacre, 3,000 to 4,000 layers of offset, aragonite bricks are locked together by thin layers of organic glue. Another example of microstructural control is that aragonite with complex microstructures can dissolve more rapidly than thermodynamically less stable magnesian calcite (Walter, 1985). Precipitated calcium carbonate (PCC) has seen a trend away from rhombohedral (a spherical pigment) to aragonite PCC (an acicular pigment). |
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