Alongside kyanite and sillimanite, andalusite is one of the three aluminosilicates that may occasionally be encountered as gemstones. The crystals possess perhaps the strongest pleochroism in the gem world, with the cutting orientation and/or viewing direction giving rise to either a brownish-red, brownish-yellow or greenish hue.
Andalusite takes its name from the southern Spanish region of Andalusia, where it was first discovered. However, Brazil is now the primary producer of gem-quality material, with significant deposits also found in Sri Lanka, Russia and the United States.
Viridine is a manganese-containing sub-species of andalusite, which is noted for its bright yellowish-green coloration. Another variety, known as chiastolite, possesses a distinctive dark cross of graphite against a light grey background and is of great interest to both mineral collectors and Christians alike.
Characteristics of Andalusite
- Hardness: 6.5 – 7.5
- Transparency: Transparent to opaque
- Chemical composition: Al2SiO5 + Fe
- Phenomena: Chatoyancy (cat’s eye), very rare.
- Refractive index: 1.629-1.690
Shapes of Andalusite
Gem shapes with a long axis such as ovals, marquise, or emerald cuts tend to show one color near the center and a second, usually darker color, near the ends. Square and round cuts usually blend the colors into a mosaic.
Sometimes, lapidaries cut these stones to show pink and almost colorless shades. Others cut to display green in the center of these stones, with browns or various other combinations on the tips, depending on the rough orientation before cutting.
Poorly cut and polished stones may appear dull. As Type II clarity grade gems, andalusites usually contain inclusions, so a large, eye-clean, well-cut andalusite will demand attention. With a hardness of 6.5 to 7.5, it could find a home in almost any type of jewelry setting.
Sources of Andalusite
Andalusite is eponymous with Andalusia, a region in southern Spain. This gem received this name from the French mineralogist Jean-Claude Delamétherie in 1798, after its supposed source. However, the material he examined came from Castile-La Mancha, a region squarely in the center of Spain. In fact, andalusite’s chiastolite variety had already been described by the Spaniard José Turrubia in 1754. Nevertheless, the name “andalusite” stuck, and so did references to Andalusia as the type locality.
Although Andalusia does produce colorless andalusites, the type locality should be noted as El Cardoso de la Sierra, Guadalajara, Castile-La Mancha, Spain.
Currently, Brazil is the main source of these gems, where they can be found as pebbles in stream beds or on hillsides under layers of clay.
Other notable gem sources include the following:
- United States: California; Colorado; Maine; Massachusetts; New Mexico; Pennsylvania; South Dakota (Black Hills).
- Belgium: blue crystals.
- Myanmar: dull green material found in gem gravels.
- Sri Lanka: gem material found as waterworn pebbles, sometimes large size.
- Australia; Austria; Madagascar; Russia; Spain; Zimbabwe.
History of Andalusite
Andalusite was given its name by Jean-Claude Delamétherie in 1798 for Andalusia, Spain where it was first discovered. However, the original form of andalusite was first found before the birth of Christ in El Cardoso, which is a different Spanish region. Andalusite is also known as the “poor man’s Alexandrite.” Cross stone is one of the alternate names of Andalusite. According to Greek tradition, andalusite is a form of Chiastolite. The ancient Greeks used these extravagant crystals for healing and decorative purposes.
Meaning of Andalusite
Andalusite is the seeing stone that promotes the desire for self-realization, helping one to rebalance and re-align. This stone helps the wearer in discovering problems and emotional blockages while pointing the wearer to a possible resolution. It is also a protection stone and used to ward off the evil eye. The stone is believed to regulate sleep and helps in alleviating the paralysis of nerves, muscles and joints. Wearing andalusite crystals is believed to help reduce fevers, the pain of arthritis, joint inflammation, gout and rheumatism. Andalusite is associated with the astrological sign of Virgo and vibrates to the number seven. It works well for the solar plexus chakra.
Care Instructions
Although resistant to scratching due to its hardness, andalusite has distinct cleavage and brittle tenacity. Therefore, ring stones should have protective settings to avoid blows.
Before subjecting any rare andalusites to mechanical cleaning systems, have a gemologist examine them and identify any inclusions they may have. While andalusites have a “Very Good” wearability score, inclusions of liquids or other minerals could shatter if heated or vibrated, thus damaging your gems. In the meantime, to be safe, use a soft brush, mild detergent, and warm water instead.