Science Fair Project Encyclopedia
Andalusite
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.
Details
| Crystallographic system | Orthorhombic |
| Colours | Brown, green, pink, violet and red varieties |
| Lustre | |
| Hardness | 7.5 |
| Refractive index | 1.641-1.648 |
| Cleavage | 3 |
| Twinning | Lamellar |
| Pleochroism | Clear to patchy pink |
Related minerals
- Kyanite
- Sillimanite
- Chiastolite
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details