Iolite: The Viking Compass

Mined predominately in Sri Lanka, India, Madagascar, Mozambique, Zimbabwe, Brazil and Burma, iolite is comprised of a complex silicate of magnesium and aluminium, but replacement of the magnesium by ferrous iron and manganese, and the aluminium by ferric iron, often occurs. These replacements make the constants for iolite somewhat variable. 

The gem is found as crystals or grains in igneous rocks, only as a result of contamination of the magma by aluminous sediment. 

Inclusions seen in iolite vary considerably, but there is one notable variety seen in Sri Lankan stones: thin hexagonal platelets of either hematite or goethite that give the stone a strong red colour, depending upon which angle it is viewed from. This is a result of a rather extraordinary optical property held by iolite in which the gem changes colour with each different viewing angle.   

 

Such an effect is due to the pronounced presence of pleochroism that allows multiple colour shades to be seen in the same gem. 

Pleochroism can make things difficult for a gem cutter. If iolite is not cut from exactly the right direction – no matter the shape of the rough – its colour will not show to its best advantage. If cut properly, the gem displays a brilliant violet when viewed from above, but may appear colourless from another angle. A cube cut from iolite will look as blue as sapphire from one side, clear as water from the other, and as gold as honey from the top. 

This water-like transparency amid blue hues is the reason that iolite is sometimes known as the water sapphire. Its true name iolite comes from the Greek word ios, which means violet. Another old name is dichroite, a Greek word meaning “two-coloured rock”, a reference to cordierite’s strong pleochroism.

In addition to creating an array of colours, pleochroism offers iolite another use. The stone was once known as the Viking compass because it can determine the direction of the sun on overcast days. When Leif Eriksson and the other legendary Viking explorers ventured far out into the Atlantic Ocean, they used thin pieces of iolite as the world’s first polarizing filter. 

Looking through an iolite lens, they could determine the exact position of the sun, and navigate safely to the new world and back. 

Iolite became known as the gemstone of clear vision and, when worn as an amulet, was believed to have the power to guide lost sailors to the brilliance of the sun in order to find their way home.

It is believed iolite also helps to open the spiritual pathway that connects the living with the dead and shamans would use this stone to ensure accuracy of visions and to influence the spirits in healing ceremonies. 

In the physical realm, iolite is used to help heal sore throats, varicose veins and blisters. Iolite is also said to be very helpful when dealing with addictions, including alcoholism. 

As a jewellery addition, the gem is most popular in necklaces or earrings, though iolite rings are also desirable. Although relatively hard – it measures 7.5 on moh’s scale – iolite should be protected from any abrasive surfaces as with any gem.