aragonite

aragonite
/euh rag"euh nuyt', ar"euh geuh-/, n.
a mineral, orthorhombic calcium carbonate, CaCO3, chemically identical with calcite but differing in crystallization and in having a higher specific gravity and less marked cleavage.
[1795-1805; named after ARAGON (the province, where first found) + -ITE1]

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A 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.

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  widespread mineral, the stable form of calcium carbonate (CaCO3) at high pressures. It may be distinguished from calcite, the commoner form of calcium carbonate, by its greater hardness and specific gravity. Aragonite is always found in deposits formed at low temperatures near the surface of the Earth, as in caves as stalactites, in the oxidized zone of ore minerals (with lead substituting for calcium), in serpentine and other basic rocks, in sediments, and in iron-ore deposits. Aragonite is the mineral normally found in pearls. It is polymorphous (same chemical formula but different crystal structure) with calcite and vaterite, and, with geologic time, probably inverts to calcite even under normal conditions. For detailed physical properties, see carbonate mineral (table—>).

      Aragonite is an important element in the shells and tests of many marine invertebrates. These animals can secrete the mineral from waters that would ordinarily yield only calcite; they do so by physiological mechanisms that are not fully understood.

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Universalium. 2010.

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  • Aragonite — is a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate, CaCO3. The other polymorph is the mineral calcite. Aragonite s crystal lattice differs from that of calcite, resulting in a different crystal… …   Wikipedia

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  • Aragonite — A*rag o*nite, n. [From Aragon, in Spain.] (Min.) A mineral identical in composition with calcite or carbonate of lime, but differing from it in its crystalline form and some of its physical characters. [1913 Webster] || …   The Collaborative International Dictionary of English

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