About Iolite (Cordierite)

Gem of the Vikings - When Leif Eriksson and the other legendary Viking explorers ventured far out into the Atlantic Ocean, away from any coastline that could help them determine their position, they had a secret gem weapon: iolite. The Viking mariners used thin pieces of it as the world's first polarizing filter. Looking through an iolite lens, they were able to determine the exact position of the sun, and navigate their way safely to the New World and back.
The property that made iolite so valuable to the Vikings is its extreme pleochroism. Iolite has different colours in different directions in the crystal.

Known in the jewellery trade as iolite, this mineral is known as cordierite to geologists and mineralogists. It was named after French mineralogist Pierre Cordier.

Facts:

• Mohs hardness: 7.0 – 7.5
• Mineral: Iolite (Cordierite)