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www.mineralgallery.co.za Minerals A-E |
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Andalusite |
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Name
Andalusite
Chemistry
Al2[O SiO4]
Uses
Manufacture of mullite refractories, especially spark plugs.
Color-
Grey,reddish-grey, brownish
Hardness
7
Specific gravity
3.1 - 3.2
Crystal system:
Orthorhombic
Accompanied by:
Garnet, tourmaline, rutile,quartz
Fracture
Uneven,brittle
Luster
Vitreous, greasy, dull
Cleavage
Good to indistinct.
Streak
White
Similar to:
Tourmaline
Andalusite occurs in elongated crystals with a square cross section. This can best be seen in the variety known as Chiastolite. It contains black or brown clay and/or carbonaceous material inclusioned in the crystal.
Andalusite is a polymorph with two other minerals; kyanite and sillimanite.
Some people believe that such crystals have magic powers and sections cut from them are frequently worn as amulets.
Occurrences include Andalusia, Austria, California, China, Spain, USA.
