Glittering Stones >> Semi Precious Stones >> Andalusite

Semi Precious Stone Andalusite

Andalusite is an aluminium nesosilicate mineral with the chemical composition of Al2SiO5. The variety chiastolite contains dark inclusions of carbon or clay that forms an X or a cross in section. A clear variety of andalusite was first found in Andalusia, Spain that can be cut into a beautiful gemstone. The faceted andalusite gemstone gives a play of red, green, and yellow colors resembling a muted form of iridescence.

Andalusite is a common regional metamorphic mineral that forms under low pressure, moderate to high temperature condition. Minerals kyanite, sillimanite are polymorphs of andalusite which occurs under different temperature and pressure regimes. Mostly, it is found together in the same rock. Andalusite was first reported from Andalusia Spain in 1789.

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Historical Facts of Andalusite

Refractive Index: 1.634 - 1.643

Chemical Composition: Al2SiO5

Hardness: 7 - 7.5

Density: 3.13 - 3.21

Crystal Group: Orthorhombic

Luster: Vitreous

Ocurrence: Brazil, Sri Lanka, Spain, East Africa, Burma, U.S.A

Color: Opaque brownish, Yellowish green, Orangy brown, Pure green, Brown, Pink, Red, Violet (rare)

Gem Stone Andalusite Jewelry