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The Mineral Aragonite
aragonite picture

aragonite picture

Aragonite is a mineral of carbonate. It is one among the two well-known crystalline forms of calcium carbonate, CaCo3 that is found in nature, (the next is the mineral calcite). Its formation occurs by physical and biological means, which includes its precipitation from freshwater and marine surroundings.

The crystal lattice of Aragonite is different from calcite; its crystal structure is different, which is an orthorhombic system (having three unequal axes at right angles) having acicular crystals (crystal mass consisting of slender needle-like radiating crystals) The Pseudo-hexagonal structure is a result of continuous twinning When two cryatals share a singular lattice point), Aragonite occurs in either fibrous or columnar form and at times in the form of branching Stalactite, known as flash-Ferri (“flowers of iron”) in context of the ore obtained at Carinthian iron mines.

Chemical Formula

CaCO3

Derivation of Name

Aragonite got its name from the Molina de Aragon site, Spain, at the place where very good trilling is obtained in the Gallo river.

Occurrence

Molina De Aragon (Guadalajara, Spain), is the exact site for Aragonite, it is located 25 km from Aragon, where it obtained its name in 1797. The Ochtinska Aragonite Cave, located in In Slovakia is a special Aragonite cave. Aragonite is available in the stalactite structure and as “cave flowers” in the USA. (Anthodite) is seen in Carlsbad Caverns and similar caves.

Aragonite occurs in the natural way in most of the mollusk shells, as calcareous endoskeleton, belonging to the cold-and warm water corals (Scleractinia). Most of the Serpulids (marine worms that live in calcareous rubes, attached to rocks) possess Aragonite tubes. The deposits of this mineral in mollusk shells are perfectly managed by biological means, therefore, few crystal structures are characteristically dissimilar to those of the inorganic Aragonite.

Gemology

aragonite picture

aragonite picture

Several crystals and organic gems are obtained from Aragonite. The gem stone, Aragonite is alluring and fascinating, and many fail to notice this because of the other expensive and showy gemstones. However the sociable and mild overbearing colors are used to generate friendly and simple designs with delicate and soft colors. Besides Aragonite is the main mineral that forms the organic compounds generally called mother of pearls.

Source

In several locations we see Aragonite crystals that are transparent, especially in Spain, Bohemia and Northern parts of England. Huge material is obtained in the form of horizontal layers. Occasionally, materials similar to marble that have sedimentary layers are considered as Mexican Onyx and made use of as ornamental items and for carvings.

Mineralogy

When compared to calcite, the Aragonite mineral is comparatively less endemic and obtained in large quantities, occurring in a limited variety of Physio-chemical environments. When compared to calcite it is metastable and frequently changes to calcite with changes in the surroundings. This mineral is frequently obtained from the surface and most of the time at low-temperature

Color

Aragonite normally occurs in white color or they are colorless, at times they are found in tints of gray, brown, violet and green.

Density 

2.947 g/cm3

Mohr Scale Hardness

Aragonite is harder than calcite (3.5-4, instead of 3, on the Mohs scale) and more or less having greater density, however it reacts with weak acids with strong boiling like calcite.




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