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  : : Andalusite Information
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Andalusite Gemstone Information

About Andalusite - History and Introduction

Andalusite is named after Andalusia, the autonomous community of Spain 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 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 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 awareness and appreciation from the eyes of many jewelry designers. It is becoming increasingly more popular in jewelry lines and designs. Andalusite possesses a good level of durability and hardness, making it suitable for any type of jewelry application. The attraction of andalusite is much owed to its play of colors from changes to 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 or idocrase. Pleochroism in gems occur in varying strengths of weak, distinct or strong. Pleochroic effects result through the differing absorption of light rays and the phenomenon can only occur with doubly refractive crystals. Andalusite is considered strongly pleochroic, along with iolite, kyanite, kunzite, sphene and tanzanite. Andalusite has trichrois 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 dichoric pleochroism, which displays 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 when they do, they tend 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 a two colors that differ in intensity, often times, 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 towards the ends of the crystal, they display a second, usually darker color. Typically, when cutting pleochroic gems, cutters attempt to minimize pleochroism and maximize the single best color. With andalusite, cutters do the exact opposite and try to orient the gem to result with 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 Mohs scale) compared to transparent andalusite. Transparent andalusite is quite rare and only a small percentage of yields are of gemstone-quality. Most specimens contain some inclusions, with the most common being rutile needles. When polished, andalusite has a vitreous to mat luster.

Andalusite Cut and Shape

Transparent andalusite is almost always table faceted with brilliant cuts. Very rarely is andalusite 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 axis properties. Square and round cuts are also popular because they will have an attractive mosaic 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 common 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 into 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: 7.50
Refractive Index: 1.627 - 1.649
Density: 3.05 - 3.20
Cleavage: Good; Uneven Fracture
Transparency: Transparent to Translucent to Opaque
Absorption Spectrum: 553, 550, 547, 525, 518, 495, 455, 447, 436
Double Refraction / Birefringence: -0.007 to -0.013
Luster: Vitreous to Mat
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 Andalusite Varieties:

Tourmaline, Chrysoberyl, Chrysoberyl Cat's Eye and Smoky Quartz are the most popular stones similar in color to andalusite. Kyanite and Silimanite are popular gem types that share the same chemical composition, but they possess different crystal structure. Tanzanite, Iolite and Kunzite also have similar pleochroic properties.

Lesser Known Andalusite Varieties:

Chiastolite (Cross Stone) is an opaque variety of andalusite. Sphene, Idocrase and Sinhalite are of the lesser-known gemstones that possess similar resemblance to 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 relation between planets and mankind. Although there are only a few current myths specific to andalusite, they have been worn in amulet jewelry for quite some time, which suggests that many older cultures believed in its crystal powers. Andalusite was likely used in ceremonial traditions 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 sections of character. Andalusite is sometimes used to encourage its wearer to rationally look at issues and to see problems from all perspectives, without fear or judgment. Andalusite helps realize that self-sacrifices are never required, but are acceptable when needed. Andalusite is believed to help with HIV (AIDS), eye disorders and boost calcium, oxygen and iodine deficiency. Andalusite is able to relieve water retention, enhance memory, bring chivalry, balance and moderation to 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 (Solar Plexus and Heart Chakra).

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 circumstance.
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 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. They are also ideal as centers for rings, bracelets, necklaces, pins, brooches, cuff-links, tie-tacks and pendants. Due to its pleochroic property, they are best suited for jewelry designs that allow light to strike the stone at many angles. Closed settings will not exhibit or allow andalusite to display its most desirable quality.

Caring for your Andalusite Gemstones and Gemstone Jewelry 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; but regardless, 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 stone 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: February-13-2014
  • © 2005-2014 all rights reserved.
    Reproduction (text or graphics) without the express written consent of (SETT Company Ltd.) is strictly prohibited.
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