Idocrase: Identification, Uses, and Meaning  

Idocrases are attractive gemstones found in limestone deposits.

These gemstones are also called Vesuvianite.

Idocrase is the preferred term for gemologists.

Vesuvianite may be a more apt name for geologists.

This article will explain Idocrases, their uses, and their associated meanings.

Idocrase (A Guide)

Properties of Idocrases

Distinct properties of idocrases make them unique in the gem world.

These properties, influenced by the origin of these gems, are responsible for the appearance of idocrases.

Chemical Properties of Idocrase

Idocrases are calcium aluminum silicate minerals with the chemical formula Ca10(Mg, Fe)2Al4(SiO4)5(Si2O7)2(OH, F)4.

An idocrase is a silicate with a tetragonal crystal system.

Physical characteristics

Idocrases commonly occur as short pyramidal or prismatic tetragonal crystals.

They have a Mohs hardness score of 6.5 with a specific gravity of between 3.32 to 3.43. Idocrases are almost insoluble acids.

Appearance of Idocrases

Idocrases are naturally occurring minerals that make gorgeous gemstones because of their appearance.

Idocrases come in a variety of colors ranging from colorless to black. Most idocrases are green, brownish-green, or yellowish-green.

These gemstones usually have a vitreous luster with poorly defined cleavage. This characteristic makes them brittle.

Where to find Idocrases

These gemstones originate in limestone collections.

Idocrases form when intrusions of igneous sediment into limestone, dolomite, or marble.

This process is known as contact metamorphism.

Lavas at the foot of Mount Vesuvius formed the first discovery point of idocrases.

Idocrases originate in several countries such as the United States, Germany, Austria, Canada, and Switzerland.

Cyprine is a variant of Idocrase that contains copper. Cyprine originates from Norway and New Jersey. Copper found in these variants gives them a blue color.

Californites appear as compact, massive idocrases with a jade resemblance and originate in parts of California.

Wiluites are optically positive variants of Idocrases found in the cold Wilui region of Siberia.

Identification of Idocrases

Identification of these gemstones is crucial in averting misrepresentation.

These mistakes lead to other potentially less valuable gems getting traded as idocrases.

Idocrases are brittle gemstones that have poor cleavage.

Vesuvianites come in different shades of green, blue, or red. An idocrase is usually translucent.

Crystal forms are common.

Vesuvianite crystals have symmetrical planes with a tetragonal structure.

Idocrases may also occur as massive compact stones.

These massive idocrases do not possess symmetrical planes.

Are Idocrases Valuable?

Yes, they are valuable.

Collectors buy idocrases from gemstone merchants.

Idocrases rank as collector’s items.

Prices of these stones vary based on the size, color, and quantity.

Idocrases look-alikes and how to differentiate them

Idiocrases may appear similar to garnets or jades with identical physical characteristics, making it difficult to differentiate them.

Garnets are nesosilicate minerals that are typically red. Garnet stones can come in different colors, though blue garnets are extremely rare. Garnets have a higher Mohs hardness score of 6.5 to 7.5.

The term Jade refers to two compact minerals that are typically green. They include:

1. Jadeite ( which are silicates of aluminum and sodium)

2. nephrites ( which are silicates of magnesium and calcium).

Jades are also brittle and have a similar Mohs hardness scale of 6.5.

Gemological testing is needed to avoid mistakes. Here are several ways to distinguish Idocrases.

Optical nature

Idocrases have a birefringence of 0.005 with weak pleochroism.

They also have a uniaxial optical character with principally a negative optic sign.

Idocrases may also be biaxial. These stones exhibit color zoning.

Refractive index

Most idocrases have the following refractive indices: nω = 1.703–1.752 nε = 1.700–1.746

However, the refractive index of the cyprine variant may be lower.


Most idocrases exhibit heat-wave effects. A unique fibrous appearance may be observed in the Cyprine variant when viewed under a magnification lens.

Uses of Idocrases

Idocrases appeal greatly to people who know their value. These gems are particularly used for their beauty and perceived metaphysical powers.

Industrial use

The physical properties of idocrases do not permit them to function as raw materials for large-scale industries. Vesuvianite is brittle and has poor fracture patterns.

Personal use

These stones are collected by mineral merchants who carve out beautiful gems or sculptures. Subsequently, these gems may be used in necklaces, rings, and bracelets and get sold in jewelry stores.


Some collectors find it interesting to search for idocrases. Collectors may go as far as visiting areas of the world where vesuvianite is predominant.

Spiritual uses of Idocrases

Some people have lauded Idocrases as mystical stones.

These people believe that Idocrases have emotional and spiritual effects on their owners.

There are claims that these gemstones can serve as links to the realm of spiritualism.

Here are some purported spiritual reasons why people would want to possess Idocrases

  • Enhanced couple partnerships: Owning idocrases is said to help lovers to be more compassionate towards each other. Idocrases are also though to boost feelings of loyalty amongst couples.
  • Spiritual realm connection: People who own Vesuvianite claim to connect to the metaphysical realm. This connection is said to help them to understand the true meaning of their lives.
  • Overcoming past mistakes: Idocrases users believe that the gemstone helps them to navigate through difficulties by learning to accept errors. These people can move on with life without bothering so much about previous mishaps.
  • Soul purification: Idocrases are said to purify souls. Purification of the soul is often a prerequisite to entering the metaphysical realm. A purified soul is maximally aligned with astral space and obtains maximum benefits.

Historical folklore of Idocase

In 79 AD, a famous volcano on Mount Vesuvius in Italy erupted.

The eruption obliterated the city of Vesuvius that lay at the foot of the mountain.

Hot lava flowed down the side of the mountain.

Upon cooling, the mineral, Vesuvius was formed.

In 1723, Moritz Anton Kappeler named it hyacinthus dictus octodecahedricus.

Jean-Baptiste Louis Romé de L’Isle renamed it hyacinte du Vesuvein 1772. However, in 1795, Abraham Gottlob Werner renamed it ‘Vesuvian’.

Thus, its name Vesuvianite has stuck around for centuries.

The term ‘idocrase’ has a Greek origin and means mixed form.

The name was because the crystals had mixtures of several mineral forms.


Idocrases are beautiful gemstones whose physical properties make them valuable as jewelry and collector’s items.

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