Andalusite gets its name from the Spanish province of Andalusia, where it was first discovered. Andalusite is an aluminum silicate that has been called the "poor man's alexandrite." Some andalusite crystals have inclusions arranged so that in cross-section, they form a dark cross. This form of andalusite is called chiastolite, which is a name that comes from the Greek word for cross. Chiastolite occurs in schists and can be found in Santiago de Compostela, a town in Northwest Spain. In the past, many amulets made of chiastolite were sold to pilgrims. Andalusite is heated to form mullite, a mineral that has many industrial uses. For example, mullite is used in the manufacturing of spark plugs. Andalusite is a polymorph with two other minerals, kyanite and sillimanite. It is a pleochroic stone; it can display shades of color varying from light yellowish brown to green brown, light brownish pink, grayish green, or definite green, with pleochrism, making it hard to identify the main color.
Transparent green andalusite is the most valued form of andalusite. Unlike other pleochroic gemstones, such as iolite and zoisite, where gem cutters try to reduce the pleochrism and highlight the single best color, cutters of andalusite actually attempt to get a good mix of colors in the stone. When cut in an emerald cut, andalusite may look mostly green, with bits of orange showing at the ends of the emerald shape. When cut in a round cut, the green body color is visible, as are simultaneous flashes of other colors. The rare and sometimes expensive emerald green colored variety may exhibit a bright yellow color simultaneously, or when viewed from different angles. In contrast, the pink variety does not exhibit this kind of color phenomenon.
Andalusite is a fairly durable stone, rating a 7 to 7.5 on the hardness scale. It is a vitreous and transparent to translucent stone. Andalusite occurs as crystals with poor luster, typically in thermally metamorphosed peltic rocks, and in muddy rocks that have been metamorphosed under low-pressure conditions. It also occurs, together with corundum, tourmaline, topaz and other minerals, in some pegmatites. Andalusite is found mainly as water worn pebbles and it is these pebbles that are usually cut as gemstones.
Beautiful dark green forms of adalusite come from alluvial gravels in Sri Lanka, while green andalusite gemstones are found in Brazil, principally in the states of Espirito Santo and Minas Gerais. Andalusite from Brazil is small, rare and very expensive. Brazil is actually the primary source for andalusite. Large columnar crystals of andalusite occur at Lisenz, Austria. Andalusite also occurs in the United States in Massachusetts, the White Mountains in California, Standish, Maine, and Delaware County, Pennsylvania. Other important sites for andalusite include Canada, Bimbowrie Australia, the Hunan Province in China, as well as various locations around Siberia, Russia, Brittany, France, and England. It has been said that the person who is attracted to this stone is a fighter. However, by wearing the stone, the wearer supposedly becomes wise, gives up fighting, and starts to embark on the path of love. With andalusite, the wearer perceives that with fighting, we live contrary to our own nature.