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  : : Andalusite Information
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Andalusite Gemstone Information

About Andalusite - History and Introduction

Andalusite is named after Andalusia, the Spanish autonomous community where it was first discovered. Andalusite is an aluminum silicate, closely related to both silimanite and kyanite. In fact, all three minerals are polymorphs, which means they share the same chemical composition, but possess different crystal structures. Andalusite is a strikingly beautiful gem, but it is largely unknown to the general public and considered to be one of the lesser-known gem types in the trade.

Andalusite has a very distinct combination of colors, and a very pronounced level of pleochroism, which results in the exhibition of different colors when viewed from different angles. Andalusite most often occurs translucent to opaque, with transparent gemstone-quality specimens being very rare. For many years, andalusite has primarily been a collector's stone, but it has recently gained a lot of attention from many jewelry designers. It is becoming increasingly popular in jewelry designs. Andalusite possesses a good level of durability and hardness, making it suitable for any type of jewelry application. The attraction of andalusite is greatly owed to its play of color, which can be seen during changes in its viewing angle. Similar effects are also seen when lighting strikes the gem from different directions.

Click to enlarge andalusite image
Natural Andalusite Gemstone
Identifying Andalusite Back to Top

There are only a few gem types that could be mistaken for andalusite, including tourmaline, chrysoberyl, sphene, smoky quartz and idocrase. Pleochroism in gems occurs in varying strengths; weak, distinct or strong. Pleochroic effects are the result of differing absorption of light rays, and the phenomenon can only occur with doubly refractive crystals. Andalusite is considered to be strongly pleochroic, along with iolite, kyanite, kunzite, sphene and tanzanite. Andalusite has trichroic pleochroism; when light enters the stone, it is parted into three sections, each containing a portion of the visible spectrum. Some pleochroic gems, such as kunzite, possess dichroic pleochroism, which means that they display only two different colors.

Andalusite Origin and Gemstone Sources Back to Top

Andalusite typically occurs in placers, gneisses, and schists as a result of argillaceous sediment that has been metamorphosed. Andalusite rarely occurs in granite or pegmatites, but it does, it tends to yield the largest crystals. Andalusite deposits can be found in many locations, including Australia, Brazil, Canada, Russia, Spain (Andalusia), Sri Lanka, Burma, Madagascar and the USA (California and Colorado).

Buying Andalusite and Determining Andalusite Gemstone Value Back to Top

Andalusite Color

Andalusite colors depend on the orientation of the crystal, but they typically occur yellow, yellow-green, green, brownish red, olive and reddish brown. Each gemstone possesses two colors that differ in intensity, and often the colors blend together, especially with square and round shapes. Shapes with a long axis, such as oval, pear, marquise or emerald cuts, tend to show one color near the center and a second, usually darker color toward the ends of the crystal. Typically, when cutting pleochroic gems, cutters attempt to minimize pleochroism and maximize one desirable color. However, with andalusite, cutters do the exact opposite and try to orient the gem to result in a pleasing mix of colors, such as orangey-brown and yellowish-green or gold.

Andalusite Clarity and Luster

Andalusite typically occurs translucent to opaque. Opaque specimens are known as chiastolite. Dark inclusions in chiastolite produce cruciform-like shapes within the stones and these are often referred to as 'Cross Stones'. Chiastolite usually occurs white, gray or yellowish and is rather soft (5 - 5.5 on the Mohs scale) compared to transparent andalusite. Transparent andalusite is quite rare and only a small percentage of yield is of gemstone quality. Most specimens contain some inclusions, with the most common being rutile needles. When polished, andalusite has a vitreous to matte luster.

Andalusite Cut and Shape

Transparent andalusite is almost always table faceted with brilliant cuts. Andalusite is very rarely cut en cabochon, with exception to opaque varieties. Andalusite color is greatly enhanced by specific orientation and cutting. Without proper cutting, andalusite would not display its desirable pleochroic shades of brown, green and reddish-brown. Oval, marquise and emerald cuts are very popular, due to their long axes. Square and round cuts are also popular because they will have an attractive mosaic-like blend of colors. Since andalusite is one of the lesser-known gemstones, trillion, heart and other fancy shapes are not very common because there is little demand for them.

Andalusite Treatment

Andalusite is typically untreated. There are no known typical enhancements for transparent specimens. Some opaque varieties (chiastolite) may be heat treated or resin-filled to enhance clarity, but this is rare. Some Brazilian material is known to change from olive-green to pinkish when heated and some brown specimens can fade to colorless when heated above 800°C. Irradiation treatment is thought to be able to reverse heat treatment results, but in any case, ehancements should be disclosed by all gemstone suppliers.

Andalusite Gemological Properties: Back to Top
Chemical Formula: Al2Si03; Aluminum silicate
Crystal Structure: Orthorhombic; thick-columnar
Color: Yellow-green, brownish-red, green
Color of Streak: White
Hardness: 7.5 on the Mohs scale
Refractive Index: 1.627 - 1.649
Density: 3.05 - 3.20
Cleavage: Good; uneven fracture
Transparency: Transparent to translucent, opaque
Absorption Spectrum: 553, 550, 547, 525, 518, 495, 455, 447, 436
Double Refraction / Birefringence: -0.007 to -0.013
Luster: Vitreous to matte
Fluorescence: Weak: green, yellow-green
Andalusite Varieties or Similar Gemstones: Back to Top
Buy idocrase gems online
Idocrase Gemstone

Only a few gem types could be mistaken for andalusite, including tourmaline, chrysoberyl, sphene, smoky quartz, idocrase or sinhalite. Due to distinct markings, it is very difficult to imitate because of its pronounced pleochroic properties. The opaque variety of andulusite is not nearly as desirable or popular as transparent, gem-quality andalusite.

Most Popular Related Gemstones:

Tourmaline, chrysoberyl, chrysoberyl cat's eye and smoky quartz are the most popular stones similar in color to andalusite. Kyanite and sillimanite are popular gem types that share the same chemical composition, but they possess a different crystal structure. Tanzanite, iolite and kunzite also have similar pleochroic properties.

Lesser Known Related Gemstones:

Chiastolite (Cross Stone) is an opaque variety of andalusite. Sphene, idocrase and sinhalite are of the lesser-known gemstones that can resemble andalusite, resulting from their pleochroic qualities.

Andalusite Gemstone Mythology, Metaphysical and Alternative Crystal Healing Powers Back to Top

As a lesser-known gemstone, andalusite produces mostly blank pages in the books of myth, history, wisdom, astrology (zodiac) and the relationship between the planets and mankind. Although there are only a few myths specific to andalusite, it has been worn as amulets for quite some time, which suggests that many older cultures believed in its crystal powers. Andalusite was likely used for ceremonial purposes and alternative healing practices.

Andalusite is sometimes referred to as the "Seeing Stone". It earned this name due to its metaphysical ability to calmly see, without bias, various aspects of character. Andalusite is sometimes used to encourage its wearer to appraise issues rationally and to see problems from all perspectives, without fear or judgment. Andalusite helps its wearer to realize that self-sacrifices are never required, but are acceptable when needed. Andalusite is believed by some to help with HIV (AIDS), eye disorders and is said boost calcium, oxygen and iodine levels. Andalusite is also thought to relieve water retention, enhance memory, encourage chivalry, balance and moderation in its wearer. Andalusite is used as a meditation and centering stone. Andalusite is a stone of Virgo and it is primarily associated with the 3rd and 4th chakras (the solar plexus and heart chakras).

Disclaimer: Metaphysical and Alternative Crystal Healing Powers and Properties are not to be taken as confirmed advice. Should you have any medical conditions, please see a licensed practitioner. This information is not to replace the advice of your doctor. GemSelect does not guarantee any claims or statements made and cannot be held liable under any circumstances.
Andalusite Gemstone and Jewelry Design Ideas Back to Top

Andalusite possesses a good level of durability and hardness, making it suitable for any type of jewelry application. It has a hardness rating of 7.5 on the Mohs scale of hardness, making it harder than quartz. Until recently, andalusite was mostly a collector's stone and rarely found in jewelry. Andalusite crystals are not commonly found in large sizes, so they are most commonly used as accent stones or in cluster designs for colored stone jewelry. It is also ideal as the center stone for rings, bracelets, necklaces, brooches, cuff-links, tie-tacks and pendants. Due to its pleochroism, it is best suited for jewelry designs that allow light to strike the stone at many angles. Closed settings will not allow andalusite to display this desirable quality.

Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamonds by weight in comparison.

Andalusite Gemstone and Jewelry Care and Cleaning Back to Top

How to Clean your GemstonesAndalusite is quite durable. Andalusite can be wiped down using any soft cloth or soft-bristled brush. A mild soap or detergent can be used, but should be rinsed well to remove soapy residue. Andalusite has an uneven fracture and good cleavage, so it is not as sensitive to blows as some other stones, such as tanzanite, topaz and diamond; however, andalusite should be protected from any hard blows to prevent fracturing. As with almost all colored stones, avoid the use of harsh household chemicals. When storing andalusite, it is best to store the jewelry or gemstone wrapped in a soft cloth or inside a fabric-lined box. To preserve andalusite polish and to prevent surface scratches, always store andalusite separately from other gems.

  • First Published: August-14-2006
  • Last Updated: May-12-2014
  • © 2005-2014 GemSelect.com all rights reserved.
    Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.
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