Iolite
Named after P. Cordier, a
French geologist. Cordierite is also known as iolite and dichroite.
Iolite displays colors ranging from deep blue, to violet and light blue
and grayish blue. It can be confused with tanzanite.Iolite, also called
Cordierite, Dichroite, or Water Sapphire when the color is not very
intense. Iolite varies from quite Deep Blue to violet Blue to
light grayish-Blue, but it always has a strong pleochroism.
Sources for
this gemstone
Sri Lanka,Tanzania and
Brazil
Treatments
Typically Iolite is not
treated.
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 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.
Care
Jewelry featuring Iolite
should not be cleaned in an ultrasonic or steam cleaner. We
recommend ionic cleaners and/or warm, soapy water and a soft brush as the best way to
clean Iolite.
Technical
Details
| Chemical
Composition and Name |
(MgFe)2
Al4 Si5 )18 Silicate of aluminium and
magnesium
|
| Hardness |
7.0
- 7.5 |
| Refractive
Index |
1.53 - 1.55 |
| Specific
Gravity |
2.54 -
2.66 |
| Birefringence |
0.005 to
0.009 |
| Crystalline
System |
Orthorhombic |
