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Download hereGENERAL DESCRIPTION
Aragonite is a triclinic, pseudo-orthorhombic, pseudo-hexgaonal calcium carbonate. It can be distinguished from calcite (of which it is a polymorphic variation) because it is not cleavable and that it does not form rhomboedric crystals. It is formed in hydrothermal contexts, close to the sources of hot water, in sea-beds or in caves.
The crystals are prismatic, pseudo-hexagonal and short. But aragonite can be more massive, forming concretions, as in caves. Aragonite forms columns known as stalactites and stalagmites as well as draperies. One of the forms of aragonite that is the highly seeked by collectors and the "flower of iron" (flos ferri) : it is shows a cluster of intersected ramifications of aragonite. It is generally white to gray, but can be yellow, green, blue or pink, according to the impurities it contains.
There are very many localities for superb aragonite: Molina de Aragon in Spain where the species was discovered, Minglanilla also in Spain (purple crystals doubles finished of 25 cm), the Prospect quarry in Australia (massive columns of violet aragonite), the Erzberg mine in Austria (flos ferri), the Santa Rita mine in Mexico, various English mines (Cumberland) and in Scotland, Sicily (Agrigento), Germany and Morocco.
In France, the most known localities are the plateau of Gergovie in the Puy de Dôme and Bastennes in the Landes.
The place of conservation of the type of this species is not known.
HISTORY : Named after its type-locality: Molina de Aragón, Spain
Species first described in 1796 by Abraham Gottlob Werner (1749-1817), German geologist
Type-locality: Molina de Aragón, Spain
CHEMICAL FORMULA : CaCO3
CRYSTAL SYSTEM : Orthorhombic
COLOR : Colorless, white, gray, brown
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White
MORPHOLOGIE : Prismatic crystals, sometimes flattened, acicular
HARDNESS : 3.5-4.0
CHEMICAL CLASS: 2.93
DENSITY : V - Carbonates, nitrates and borates
GROUP : Aragonite
STRUNZ CLASS BEFORE 2001 : 5/B.04-10
STRUNZ CLASS AFTER 2001 : 5.AB.15
