Aragonites

Aragonite is a mineral form of calcium carbonate, with the chemical formula CaCO3. It is one of the three most common crystal forms of calcium carbonate, the others being calcite and vaterite. Aragonite is metastable at room temperature and pressure, meaning it can transform into the more stable calcite under certain conditions. It is found in a variety of geological environments, including sedimentary rocks, metamorphic rocks, and hydrothermal veins. Aragonite also occurs in biological structures, such as the shells of marine organisms and the skeletons of corals.

The crystal structure of aragonite is orthorhombic, differing from the trigonal structure of calcite. This difference in crystal structure leads to variations in physical properties, such as hardness, density, and optical characteristics. Aragonite crystals are typically prismatic or acicular in habit and can form in diverse colors, including white, colorless, yellow, brown, and grey, depending on the presence of impurities. It can be found in speleothems within caves, as well as in evaporite deposits. Many examples of aragonite are found in oolitic formations and as replacements of other minerals.

Aragonite has several applications. It is used as a source of calcium carbonate in industries such as cement production and as a material in the manufacture of lime. In jewelry, aragonite is sometimes used as a gemstone, particularly when it exhibits attractive colors or forms. Its presence in geological formations can provide insights into past environmental conditions. Due to its transformation to calcite, aragonite's persistence in the geological record can indicate specific formation conditions.

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