Mineral description : Andalusite

A small red andalusite crystal from Umeå. The andalusite crystal is the red square at the right of the biotite flake.
Another view after I removed the feldspar on one side of the crystal.
Two andalusite crystals from Godkärra. In biotite and feldspar.
Andalusite crystals from Godkärra. In biotite and feldspar.
Andalusite crystals from Godkärra. Squarish crystals in feldspar.

Chemical formula Al2SiO5
Hardness 6.5-7.5
Density 3.16-3.20
Color red to brown.
Habitus Ortorombic. Usually prismatic crystals with square cross section.
Cleavage Distinct prismatic, fracture uneven to subconchoidal.
Luster Vitreous.
Description
Occurance In metamorph rock as schist, quartzite and sometimes in pegmatites and hydrothermal veins.
Associates In pegmatites with korund, turmaline, topas.
Notes Polymorphs : Kyanite and Sillimanite
Andalusite is created in temperatures from 250-800 degrees C and pressures from 0 to 4 kbar.
Flourescens : weakly green, green, yellowish green.
Locations
  • Locally in mica schist and quartzites, especially around the ores in the Bergslagen and Skellefte fields.
  • Falu mine, Garpenberg mine in Dalarna.
  • Kristineberg, Boliden and Mångfall mountain in the Skellefte field.
  • Kolsva feldspar mine.
  • Persgruvan in Riddarhyttan.

To silicate index.
Mineral group index.
Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.


axelsson@acc.umu.se
To my homepage.
Last changed : 1998-03-07