Iolite Gemstone (Cordierite, Dichroite)

NamePropertiesValue, Use, Particular PropertiesSuperstitionsMines

Iolite — is a gemstone, known under the several names, such as “Cordierite,” in honor of French mineralogist Cordier, “Dichroite,” thanks to its optical properties, “white-sapphire,” due to its similarity with genuine Sapphire. Iolite possesses smoky-blue or violet to yellowish-white color, depends on the angle of view, thanks to its optical properties, known as dichroism and pleochroism.


Iolite Gemstone

Iolite derived its primary name from the two Greek terms “ion” and “lithos”, that meant “violet stone,” respectively, whereas its second name “Dichroite” derived from the Greek word “dichroos,” which means two-colored. The third name, as described above, is connected with French mineralogist and geologist Pierre Louis Antoine Cordier, who was a founder of the French Geological Society.


Iolite is usually smoky-blue, deep-blue or violet in color, that are most valuable, however, it occurs of yellow, brown and green color. As regards to the transparent specimens, Iolite is known, thanks to its similarity with White Sapphire, thus sometimes it is called “sapphire d’eau.” However, Iolite inferior to Sapphire in its hardness, which is 7-7.5/10, according to the Mohs Scale, and it possesses strongly marked dichroism, which distinguishes it from other gemstones, including the inferior fakes.

Value, Use and Particular Properties

Iolite is a pretty valuable gemstone, some its specimens could be classified as precious stones, in spite of their lack of in the list of precious stones. Nonetheless, Iolite is the rare collectible gemstone, though, it is suitable for jewelry purposes.

The specimens of Iolite of small size are frequently used in modern jewelry, however the big stones are infrequent yet, due to the flaws, that are frequently met on its surface. Flawless, big, faceted Iolite of deep-violet color, or, in turn, transparent Iolite is a sufficiently valuable gemstone, which could be classified as a genuine precious stone.

There are the evidences, that the Iolite has been used by our ancestors to define an exact position of the sun, thanks to its dichroism, so-called “Viking compass”. Such term as the polarization of light, is a known optical particularity of some gemstones. Such gemstones as Iolite, Fluorite and Euclase are used in the scientific gadgets, medical equipment and in aviation, thanks to their useful optical properties.


There are, furthermore, the several superstitions, in regards to the Iolite. In the Scandinavian countries, Iolite is the family stone, which is contributing to establish the family relationships, thus this gemstone helps to extinguish any conflicts.

There are not so much actual information, concerning healing properties of Iolite, however, there was a belief, that Iolite is the perfect remedy against insomnia.


The principal deposits of Iolite located in Sri Lanka, where the best specimens of Iolite have been obtained, however, this gemstone also mined in Brazil and in the United Sates. It is reported, that the specimens of Iolite suitable for jewelry purposes were found in Haddam and Guilford (Connecticut). Iolite mines were also discovered in Myanmar and Australia.

However, there is an opinion, that Iolite has been previously found in the Scandinavian countries, and was known even to the Vikings. Thus, Greenland, Finland and Sweden are the countries, where the Iolite mines are also located.

Image credit to: David Abercrombie

June 23, 2018

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