Andalusite is a mineral formed by the metamorphism of aluminous shales and slate. It is used in the manufacture of spark plugs and other porcelains and may serve as a gem stone if it is clear and transparent, and exhibits the optical phenomenon of pleochroism - that is the capacity to appear in different colours when viewed in different lights and from different angles. It is named from Andalusia, a province of Spain where it was first discovered. It has the formulae Al2SiO5 and a relative hardness of 8. Research Andalusite
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Matt and Leela Probert
Abbreviations
Rocks & Minerals
Research Andalusite
