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Iolite
Iolite
is a relatively plentiful stone offering an excellent
substitute to the more expensive blue Sapphire. It is a trichroic
(three-colored) gemstone, which means it shows different colors when viewed
from different directions -- usually deep blue, violet blue, and light gray.
Since the blue color is normally oriented to be viewed from the table, most
people consider Iolites to be blue.
The Vikings found that due to its ability to polarize light, looking through a
thin slice of Iolite cancels out most haze and clouds, making the sky appear
clearer. This enabled them to navigate safely in the rain. Iolites naturally
occur almost exclusively in granite, and have been frequently found in the 1-10
carat range. Also referred to as "Water Sapphire," the name Iolite is
from Greek ios color(violet) + lithos (stone).
TREATMENT: There is no known treatment for Iolite
MOHS HARDNESS: 7-7.5 (requiring only normal care)
CHEMICAL COMPOSITION: Mg 2 Al 4 Si 5 O 18
REFRACTIVE INDEX: a=1.522-1.558 b=1.524-1.574 c=1.527-1.578
(The angle light is bent traveling through a gemstone)
SPECIFIC GRAVITY (DENSITY): 2.53-2.78
(The number of times heavier a gemstone is compared to water)
PRINCIPAL SOURCES: India, Sri Lanka, Tanzania, Brazil, USA
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