Iolite
 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 position, they had a secret
gem weapon: iolite. The Viking mariners 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.
The property that made iolite
so valuable to the Vikings is extreme pleochroism. Iolite
has different colors in different directions in the crystal.
A cube cut from iolite will look a violetish blue almost
like sapphire from one side, clear as water from the other,
and a honey yellow from the top. This property led some
people to call iolite "water sapphire" in the
past, a name that is now obsolete.
 Pleochroism
may have been helpful in navigation but it makes things
difficult for a gem cutter. If iolite is not cut from exactly
the right direction, no matter the shape of the rough, its
color will not show to its best advantage.
The name iolite comes from
the Greek ios, which means violet. Iolite is usually a purplish
blue when cut properly, with a softness to the color that
can be quite attractive.
Iolite is readily available
and surprisingly affordable. The better and richer the blue,
the better. It is mined in India, Sri Lanka, Mozambique,
Zimbabwe, and Brazil. The Vikings probably mined iolite
from deposits in Norway and Greenland.
Iolite is relatively hard
but should be protected from blows. With its attractive
colour and reasonable price, it may become a jewelry staple
in the future.
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