Prehnite Gemstone Information

Prehnite is a rare gemstone that forms as a result of hydrothermal action in mafic volcanics and was named after the Dutch Colonel Hendrik Von Prehn who discovered the stone in the 18th century. In China it is also known as Grape Jade due to its nodule formations which often have the appearance of a bunch of green grapes. Prehnite is an attractive collecters stone that is becoming more well known and used for jewelry purposes. Its color is usually a soft apple green which is quite unique to prehnite.

The prices, uses and value of Prehnite can differ greatly, depending on the size and quality of the  individual gemstone. AJS Gems is your source for the highest quality colored gems from across the globe, available at Bangkok direct wholesale prices. Creating the finest jewelry starts with finding the best gemstones, and the best gemstones are found at AJS Gems.

Why Buy Loose Gemstones Instead of Pre-Set Jewelry?
There are many reasons, but basically it boils down to value and choice.

When buying your Prehnite gemstone loose instead of a pre-set stone, you can be sure you are getting the best value for your money.  Loose gemstones are less expensive, a better value, and you can really see what you are paying for.  The most important part of getting the right price and finding the best value is to first see what you're getting.  A jewelry setting will hide the inclusions inside a gem, and can deepen or brighten its color.  With a loose stone you can much more easily inspect the gem and see it for what it really is.  In this way you can get a better idea of its true worth and be sure you are paying a fair price.

The second advantage of buying a loose gemstone is choice.  You are free to pick the exact color, cut, shape and variety of the stone for the setting of your dreams, be it yellow gold, white gold, platinum or silver; prong set or bezel set with diamond accents.  You can experience the joy of creating your very own, one-of-a-kind jewelry design. Choose from a variety of jewelry settings and styles to create a completely original presentation that will perfectly suit your individual gemstone and will be as unique as you are!

Prehnite Ring                                                          



Origin Most Prehnite is mined in Australia, China, United States, and France.
Color Pale green, yellow, yellowish green, grass green, also gray, white or colorless
Refractive Index 1.61-1.64
Chemical Composition  Ca2Al2Si3O10(OH)
Hardness  6 - 6.5
Density 2.85-2.95
Crystal Structure Orthorhombic

Prehnite is a translucent to transparent hydrated calcium aluminium silicate with an RI of 1.61 to 1.64.  The refractive index (RI), measured using a refractometer, is an indication of the amount light rays are bent by a mineral.  Birefringence is the difference between the minimum and maximum RI. When birefringence is high, light rays reflect off different parts of the back of a stone causing an apparent doubling of the back facets when viewed through the front facet.

The hardness of Prehnite is around 6. Its chemical composition is Ca2Al2Si3O10(OH)2 (calcium aluminum silicate hydroxide).

Most gems have a crystalline structure. Crystals have planes of symmetry and are divided into seven symmetry systems. The number of axes, their length, and their angle to each other determine the system to which a crystal belongs. Prehnite has an orthorhombic crystal structure with an mm2 point group. and usually forms as radiating botryoidal masses. One is able to cleave prehnite easily along the  crystallographic axis but only poorly along the opposite axis. Crystal habits include nodular, concretionary, radial, encrusting and stalactitic formations among other similar types. Tabular or pyramidal individual crystals are rare but some nodular specimens show tabular crystal protrusions. Epimorphs (crystal growth over the surface of another mineral) over laumontite are usual, but available. 


The main colors of Prehnite are pale green to dark green, with yellow, white and clear forms occurring in some locations.  However most Prehnite is usually green, grey, yellow or white in color.


In regards to cut, Prehnite gemstones are usually fashioned in one of the following methods:

Tumbling: all grades can be tumbled to produce attractive stones.

Cabochons: pendants etc, medium to high grade material can be cut into various shapes for jewelry.

Faceted stones: high grade material can be cut for jewelry.

Specimens: samples have attractive features such as botryoidal structure, radiating rosettes and color variations.

Carving: all grades can be carved for decorative pieces.



Prehnite gemstones are not normally known to be treated.

AJS Gems fully discloses any and all treatments to our gemstones.

Prehnite, which is semitransparent to translucent, is a secondary or hydrothermal mineral that occurs in veins and cavities in mafic volcanic rocks.  Prehnite is a typical product of low-grade metamorphism. 

The main occurences of Prehnite gems are located in Africa (Namibia, South Africa), Europe (Germany, Scotland, France), USA (New Jersey, Pennsylvania, Virginia), Australia (Western Australia, Northern Territory).

The Australian deposits occur in scattered outcrops of Antrim Plateau Volcanics of early Cambrian age (ca. 570 million years). The volcanics consist of massive, vesicular and amygdaloidal basalt with individual flows up to 60m thick. They are mainly of sub-aerial origin but show some shallow water features locally. Vesicles and geodes contain quartz(clear, smoky, amethyst), prehnite, calcite, zeolites and copper minerals. The volcanics are of extensive distribution in the East Kimberley and adjoining Northern Territory, covering thousands of square kilometers.

The name Prehnite comes from Dutch Colonel, H. Von Prehn, the discoverer of this gemstone.

Prehnite is a very protective stone and can protect one on all levels. It strengthens the life force and generally increases and stimulates energy. It aids spirit communication through meditation or visualization, out-of-body travel, and is a powerful dream stone.

Prehnite is also known as a stone of prophesy which stimulates inner-knowing.

Physically, prehnite is helpful in the healing of gout, anemia, and kidney problems.

Prehnite allows you to make contact with those not in the physical world--those on the spiritual plane. It is, in spite of its color, a protective stone. Prehnite acts as a magnifier, especially of personal energy--strengthening the protection you have, strengthening your auric field, etc. It also works well in crystal grids, magnifying the purpose of the grid.

Prehnite works well for meditation. This crystal is useful for dreaming and remembering those dreams. It also helps develop your intuitive senses. It helps develop intuitiveness, and it will help your predictions to develop great accuracy, especially when it is an issue of your spiritual development.

The Prehnite crystal can sometimes give off water when the stone is heated.


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