Encyclopedia > Andalusite

  Article Content


Andalusite is an alumino-silicate mineral with the chemical formula Al2SiO5.

Occurrence Andalusite is a common metamorphic mineral which forms under high pressure and/or temperature. The minerals kyanite and sillimanite are polymorphs of andalusite, each occurring under different temperature-pressure regimes and are therefore rarely found together in the same rock. Because of this the three minerals are a useful tool to help identify the pressure-temperature paths of the host rock in which they are found.


Crystallographic systemOrthorhombic
ColoursBrown, green, pink, violet and red varieties
Refractive index 1.641-1.648
PleochroismClear to patchy pink

Related minerals

  1. Kyanite
  2. Sillimanite
  3. Chiastolite[?]

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
List of Amiga Games

... Action Service[?] -- Action Stations![?] -- Addams Family, The[?] -- Adidas Championship Football[?] -- Advanced Destroyer Simulator[?] -- Adventures of Robin Hood, The[?] ...