Andalusite

Andalusite is named after Andalusia, the province of Spain where it was first discovered. A polymorph with two other minerals, kyanite and sillimanite, it shares their chemistry but has a different crystal structure. A unique variety of Andalusite is called "chiastolite" and contains black/brown clay and/or carbonaceous material in crystal inclusions that are arranged in regular symmetrical shapes; usually in the form of a cross or X. Mined in Brazil and Sri Lanka, Andalusite also occurs in Andalusia, Spain; Austria; California, USA and China.

Andalusite is pleochroic (i.e. displays different colors in different directions) and is white, red, brown, orange and green in color. Having a vitreous luster, Andalusite's crystals are transparent to translucent. Its hardness is 7.5 and it has a specific gravity of approximately 3.15+ (i.e. above average). Andalusite's associated minerals are cordierite, biotite, feldspars, quartz, kyanite and sillimanite.

When cutting most pleochroic gemstones, such as iolite and tanzanite, cutters typically try to minimize the pleochroism and maximize the single most prominent color. Interestingly, Andalusite is the opposite, as cutters try to orient the gem to get a pleasing mix of orangey brown, yellowish green and gold colors. When cut successfully, Andalusite looks unlike any other gemstone, displaying patterns of color dancing around its facets. Superior color play is seen in fancy cuts, particularly rectangular cushion variations. While dependent on the skill of the cutter, in round cuts the colors can tend to blend together.

Andalusite has previously been referred to as "poor man's alexandrite" because it offers color play at an affordable price. However, this could be viewed as technically incorrect as Andalusite features all its colors at the same time, whereas alexandrite changes from green to red in different sources.

Andalusite is a gemstone that offers a lot of impact inexpensively. Certain to appeal to those who like earth tones; it is frequently used in men's jewelry due to its color and durability.