Vasonite (aka vesuvianite) is a little-known gem that has recently started to come into popularity.
In its mineral form it is known as vesuvianite, but in its crystalline form, it goes by the name idocrase.
It is a very beautiful gemstone, so use these easy tips below to be sure to identify it.
Vasonite (aka Vesuvianite) Explained
Breaking it down: what is vesuvianite?
Vasonite (aka vesuvianite) is a mineral usually found in igneous rock formations, generally in marble, skarn, dolomite, or limestone.
Its chemical composition is calcium aluminum silicate.
While it is mostly found in a rather dull, greenish hue, there are some stunningly beautiful and very valuable crystals that are used for jewelry.
It was first discovered in 1795 by Abraham Gottlob Werner outside of Mt. Vesuvius within the lava rocks, which is how it gots its name.
The next year, the gemstones were renamed idocrase by René Just Haüy from two Greek words meaning “mixed form”.
Now, the name ‘vesuvianite’ is reserved for the dull, granite-looking slabs, while the sparkly gemstones are called ‘idocrase’.
The vesuvianite rocks aren’t generally put to much use, but the idocrase crystal is getting more and more popular for jewelry and decorative pieces.
It is also sometimes called vasonite, but this is actually a fairly common misnomer, most likely derived from a misspelling of the word ‘vesuvianite’.
Tips for identifying vesuvianite
As vesuvianite continues to grow in popularity, it is important to be able to distinguish vesuvianite from other similar gems.
Here are some simple ways to do so.
Determine the color
Vesuvianite, whichever form in which it’s found, is almost always a light green color.
In the rock form, it always has a white streak running through it.
Rarely, it can be found in other colors, but the most vastly common color is a light, yellowish green to brownish-green due to the variety of minerals included in the chemical composition.
See if it’s translucent or opaque
When looking for idocrase, the crystalline form, you want to keep an eye out for a translucency similar to that of a quartz crystal.
This means that light will shine through the crystal.
However, in the case of vesuvianite, the rock, it is a very opaque stone, similar to that of granite.
Look for the luster
When you are determining the luster, look for how easily light reflects off the stone.
Vesuvianite has a few different luster possibilities.
For the crystal form, it will have a very reflective surface referred to as vitreous; this means that the luster is similar to glass.
In the rock formation, it does not have a very strong luster, being a dull stone.
However, in the case of californite, which is a specific type of vesuvianite, it will have what is referred to as a greasy luster, which can appear waxy.
Test the hardness
Although this sounds like it might be a complicated thing to test, it is actually quite simple.
The MOHS hardness scale was determined to find a stone’s hardness.
It is a scale of one to ten, with one being softest and ten being hardest.
Vesuvianite is around a six and a half on the MOHS scale, which makes it a little softer than most stones.
To test this, try scratching something lower on the scale, like a glass plate, which is at a five and a half.
If the stone is able to scratch glass, then you know that it’s higher up.
Next, try scratching the stone with something above a six and a half, like a piece of quartz, which is a seven.
If the stone passes both tests, then you’ll have a very accurate reading of its hardness.
Look for the cleavage
A stone’s cleavage refers to the angle at which it breaks.
Vesuvianite has an interesting cleavage because it is very brittle, so it doesn’t cleave at a specific angle.
While usually the cleavage is something measurable, in this case, you can count on a messy cleavage to help you identify vesuvianite.
Look out for stones that look like vesuvianite
Since vesuvianite is a relatively rare gemstone, be wary of other light green stones that may take on a similar appearance.
Peridot is a crystal that shares the same yellowish-green to dark green hues as vesuvianite, so it can be difficult to tell the difference when polished.
However, in its raw state, it is easier to tell the difference.
While vesuvianite is found in more traditional-looking crystal clusters, raw peridot comes in larger spears, and is slightly less lustrous than vesuvianite.
Jade is another light green, brittle, vitreous stone that can pose as vesuvianite.
However, it can be differentiated by its lack of translucency.
Although it can become illuminated by light, it doesn’t have the same translucent sheen as vesuvianite.
Green garnet has a very similar chemical composition as vesuvianite and, as such, can take on a very similar appearance, including luster and translucency.
It does have subtle differences, though.
Garnet is between a seven and seven and a half on the MOHS hardness scale, making it slightly harder than vesuvianite.
A simple scratch test can help you determine the correct hardness.
Different kinds of vesuvianite
Vesuvianite is a stone that comes in a few different forms.
Californite is one that most resembles jade and is found, predictably, in California.
In New York you can find xanteithis, which takes on more of a yellowish-green hue.
Cyprine is a rarer type of vesuvianite found in Norway that takes on more of a bluish tone, sometimes almost looking grey.
Russia houses a deep, dark green, sometimes even brown, variety called wiluite.
How to care for vesuvianite
Since vesuvianite is brittle and a little softer than most crystals, it is best to treat it with care and keep it away from other stones.
Store it outside of a jewelry box, where it can’t be easily scratched by other jewelry pieces.
Clean it gently with some water and a soft washcloth.
Vesuvianite is a remarkable stone, especially if it comes from the lava of Mt. Vesuvius.
If you are lucky enough to have one in possession, be grateful that you are able to hold a real piece of history in your hands.
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