Andalusite is named after a province in Spain, where it was first discovered. It is pleochroic, which means it shows different colours in different directions. When cutting most pleochroic gemstones, such as iolite and tanzanite, the trick is to minimise the pleochroism and maximise the single best colour.

With andalusite the opposite applies. The cutter's goal is to orient the gem to achieve the mix of color that will bring out the orange-brown, yellowish-green, or gold mixture for enhanced visual effect.

Andalusite looks quite unlike any other gemstone, with patterns of colour dancing around the facets. The best colour play is seen in fancy shapes, particularly rectangular cushion shapes. In round cut Andalusite, the colors seem to blend together.

Andalusite is mined in Brazil and Sri Lanka. I will research the current presence of Andalusite in Spain and add that information at a later time.

In the past andalusite was sometimes called "poor man's alexandrite" because it offers colour play at a low price, but in fact it does not actually bear much resemblance to alexandrite, which changes from green to red in different light. In fact it is not really a colour-change stone at all because the colours are present at the same time.

That should not diminish its appeal, especially for those who like earth tones. Andalusite offers plenty of impact at a relatively low price. Because of its colour and its durability, it is especially appropriate for men's jewelery.

Category: mineral
Chemical formula: Al2SiO5
Color: transparent to opaque brownish or yellowish green to orangy brown; may be pure green, brown, pink, violet (rare), and red
Crystal system: orthorhombic
Twinning: lamellar
Cleavage: distinct in one direction
Fracture: uneven to conchoidal
Mohs Scale hardness: 7 - 7.5
Luster: vitreous
Polish luster: vitreous
Refractive index: 1.634 - 1.643 (+/-.005)
Optical Properties: double refractive, biaxial negative; chiastolite has anomalous aggregate reaction.Can also display chatoyancy.
Birefringence: .007 - .013
Dispersion: .016
Pleochroism: Strong. Brownish to yellowish green and brownish orange to brownish red
Ultraviolet fluorescence: inert in long wave, inert to moderate green to yellowish green in short wave
Specific gravity: 3.17 (+/- .04)

Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
International Colored Gem Association: Anadalusite

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