Idocrase Gemstone Information

Idocrase is a fascinating mineral found originally on Mt Vesuvius, the famous volcano in Italy which erupted violently during the Roman Empire in 79 AD, and destroyed the city of Vesuvius, burying it and all its inhabitants in ash. Hence this gem is sometimes known as Vesuvianite. The name idocrase is from the Greek and means mixed form, due to its crystals showing a mixture of other mineral forms. Idocrase gemstones come in lovely shades of green that can strongly resemble Jade, a stone that Idocrase is sometimes mistaken for. In a very rare form it occurs in a transparent variety that can be faceted, making a lovely gemstone that is perfect for jewelry.

The prices, uses and value of Idocrase vary tremendously, depending on the size and quality of the gemstone. AJS Gems is your source for the highest quality colored stones 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 Idocrase loose instead of as 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!

We have become one of the world's leading precious and semi-precious loose Idocrase dealers with one of the most extensive selections of fine Idocrase gems.  At AJS Gems, you will find a large collection of Fine Quality Wholesale cut loose Idocrase gemstones to help add beauty, fun and maybe a little extra love to your life.


Origin Africa; Quebec, Canada; California and the New England region of USA; Mt Vesuvius, Italy; Ural Mountains, Russia and Switzerland.
Color Normally green, also brown, yellow, brown-black, light green, grass green, lime green, yellowish green, emerald green, white, red, purple, violet, blue-green to blue
Refractive Index 1.698 - 1.736
Chemical Composition  Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4
Hardness 6.5
Density 3.35 - 3.45
Crystal Structure Tetragonal
Zodiac Signs    Sagittarius and Capricorn

The Idocrase crystal is a complex mix of metals, oxygen, hydrogen, and fluoride. Also known as Vesuvianite, this gem is a green, brown, yellow, or blue silicate mineral. Idocrase occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism.

The hardness of Idocrase is 6.5. Its complex chemical composition is  Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4, an aluminum calcium silicate.  Refractive inices for Idocrase range from 1.698 to 1.736. 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.

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.  Idocrase has a tetragonal crystal structure. Crystal habits include prismatic crystals with an overall square cross-section. There is usually two sets of four sided prisms with one set being dominant. The termination is usually a four sided pyramid that can be either steeply or gently sloped. The faces of the pyramids align with the faces of the prisms making an edge that is perpendicular to the length of the crystal (as opposed to the tetragonal mineral apophyllite). A pinacoid can truncate the pyramid or form the entire termination. Massive forms are common and difficult to distinguish from massive garnet.


Almost all the Idocrase gem material that has been used in jewelry is some shade of green;  some massive Idocrase with a good potential for future use as a jewelry gemstone is of one or some combination of the following colors:  white, yellow, reddish brown, lilac or even bluish;  also, some of the massive green idocrase, widely referred to as californite, no matter where it was recovered, has streaks or irregular speckles of one or more of these other colors.


Transparent faceted Idocrase is uncommon, but when found is available is most popular cuts, such as round, marquise, emerald cut, trillion, oval, cusion pear, and many more.  Cut Idocrase crystals make fine gemstones for jewelry as well as fine carvings of stones made up largely of vesuvianite and grossular-vesuvianite, the latter usually called grossularite-idocrase.  These cut Idocrase stones can be used in rings, but are best suited for pendants, bracelets, earrings and necklaces.

Idocrase gemstones are not normally known to be treated.

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

Idocrase occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence it's alias, Vesuvianite.

Italy and Quebec, Canada, are well known locales for yellow, green, and brown idocrase up to about 10 or 15 carats. Faceted stones often resemble grossular garnet.

The finest U.S. idocrase crystals have come from an asbestos quarry at Eden Mills, Vermont, embedded in quartz, where they form green, brilliant, prismatic crystals terminated by a pyramid. At the Jeffrey Mine, Asbestos, Quebec, idocrase forms loose agregates of pale green crystals -- rarely tipped with violet. Large, brown, corroded but shiny crystals with rounded edges and consisting of a base and prisms are found near Olmstedville, New York, where they have been freed from crystalline calcite by weathering. Large, green, corroded, short-prismatic, and bipyramidal crystals have been uncovered in the fields at Magnet Cove, Arkansas and in Luning, Nevada. Limestone quarries at Crestmore, California, were once famous for their green-brown bipyramidal crystals in blue calcite. Small emerald green prismatic crystals of gem quality have been found at Georgetown, California. The massive green idocrase gem known as californite has been found in Butte and Fresno counties, and along Indian Creek in Siskiyou Co. in California. In Mexico it is associated with the grossular crystals.

Idocrase is also common abroad and was first recognized as a distinct mineral in Italy, where it was found on the slopes of Vesuvius (Monte Somma) in metamorphosed limestone blocks expelled from the crater; thus the name vesuvianite. At Pitkaranta (Russia, but formerly Finland) the light brown idocrase crystals are long and thin, like a bundle of cut nails. Steep, gemmy pyramidal crystals are found in Pakistan. Cuttable yellow-brown crystals come from Quebec and Tanzania.

Idocrase Source Mount Vesuvius

The Jeffrey Mine in Asbestos, Quebec has afforded facet rough that is predominantly yellow-green in color, similar to peridot; the mine has also produced an emerald green chrome-bearing idocrase and a violet to magenta manganoan vesuvianite that is sometimes called “manganovesuvianite” (this term is too close to the name of a different, non-gem mineral species, “manganvesuvianite” for comfort and should be discouraged). Bicolored facetted stones consisting of yellow-green common idocrase on one side, and pale magenta manganoan idocrase on the other, have been cut. Italy – most notably Bellecombe in Val d’Aosta has produced greenish brown to brown faceting rough. During the past decade, Fushan, Hebei Province, China has produced moderate quantities of deep yellow-brown (sometimes called “root beer”) colored crystals with gemmy areas capable of being facetted and cut en cabochon. Kaiiado District, Rift Valley Province, Kenya has produced greenish yellow to yellowish green idocrase faceting rough.

Cyprine - The original Norwegian find was of no interest as a gem material, but a significant quantity of cyprite was uncovered in 1922 during mining at Franklin, New Jersey, about 850 feet underground. Reports have been made of facetted specimens of cyprine from Sri Lanka, Jakobsberg Mine, Varmland, Sweden, and Pakistan; all are a pale blue tinged with grey.

Californite - Northern California has produced Californite at several locations, including Happy Camp in Siskyou County, the Pulga Deposit on the North Fork of the Feather River, Butte County, and Tulare County.



The name Vesuvianite comes from the famous locality in Italy, Mt. Vesuvius.

The name Idocrase comes from the Greek word "eidos", meaning "form" and "krausis" meaning "mixture".

Idocrase is believed to be a crystal of loyalty and cooperation.Idocrase helps to clear negative thoughts, and dispels anger, depression, and fear. Idocrase is said tocreate a sense of self-security and courage.
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