ANDALUSITE

ANDALUSITE	Noted for its pleochroism
Major Sources	Brazil, Mozambique, Spain & Sri Lanka
Colors Found	Brown, green, orange, red & white
Family	Andalusite: Al2SiO5 + Fe
Hardness	7.5
Refractive Index	1.62–1.65; Biaxial (–)
Specific Gravity	3.05–3.20
Crystal System	Orthorhombic
Enhancements	Natural

Andalusite, an aluminum silicate, derives its name from the site of its discovery, Almeria in the southern Spanish province of Andalusia.
While andalusite’s color play has been compared to alexandrite, this is technically incorrect, as pleochroic (displaying different colors in different directions) gemstones like andalusite feature all their colors at once, whereas alexandrite only changes color in different light sources.

Legends and lore

Some andalusite crystals have carbonaceous inclusions, arranged so that in cross section they form a dark cross. This variety is called chiastolite (named after the Greek word for cross) and sometimes referred to in ancient texts as “lapis crucifer,” meaning “cross stone.” Chiastolite is found in schist formations near the town of Santiago de Compostela, northwest Spain, and many amulets of the cross stone were once sold to pilgrims. It is often mentioned as a gemstone of protection and was once used to thwart evil eye curses.

Andalusite is considered by crystal healers to be a gemstone that enhances intellect, problem solving abilities and mental clarity. It is also mentioned as being conducive to the receipt of messages from the netherworld.

Just the facts

Andalusite is polymorphous with two other gem minerals, kyanite and sillimanite. This means they are identical in chemical composition, but differ in crystal structure. Andalusite typically occurs in thermally metamorphosed pelitic rocks, and in pelites that have been regionally metamorphosed under low-pressure conditions. It also occurs, together with corundum, tourmaline, topaz and other minerals in some pegmatites.

This gems’s main claim to fame is its extraordinary pleochroism. When cutting strongly pleochroic gemstones (iolite, tanzanite, kunzite, etc.), lapidaries typically try to minimize the pleochroism and maximize the single most attractive color. Interestingly, andalusite is the opposite, as all the colors visible in different directions are attractive. Cutters therefore try to orient the gem to get a pleasing mix of its orange, brown, yellow, green and golden colors. When cut successfully, andalusite looks unlike any other gemstone, displaying patterns of color dancing around its facets.