iolite
iolite from Tanzania
iolite crystals from Norway
solid like inclusions
solid inclusions in cordierite showing its dark color
solid inclusions in cordierite showing its light color
solid like inclusions : mica
Detailed sheet
iolite
It was also known as “dichroïte” (because of its strong dichroism) or “iolite” (because of its purple color), the anglo-saxons still call it by that name. It honors the name of the French geologist Cordier, Professor at the National Museum of Natural History in Paris.
It was also called “compass stone” or “stone of the Vikings” because they had observed that it remained straight in the axis of the sun even though it was obscured by haze.
CHEMICAL CHARACTERISTICS
Mg2Al4[Si5O18]
magnesium aluminium silicate
PHYSICAL CHARACTERISTICS
Main color
blue
Other colors
purple
sometimes brown shades
Color of streak
white
Luster
greasy, vitreous
Hardness
7.0 to 7.5
Density
2.58 to 2.66
Cleavage
good
Fracture
conchoidal
OPTICAL PROPERTIES
Transparency
transparent
Refractive index
1.510 - 1.580
Double refraction
0.010
weak biaxial (-)
visible double refraction
Yes
Dispersion
0.017(0.009)
Pleochroism
very strong
Number of colors
3
purple-blue, pale blue-gray, yellow-brownish
Absorption spectrum
492 - 456
cordierite spectrum system
Fluorescence
none
Inclusions
numerous inclusions of goethite flakes, hematite and mica, which give it the brown shades
CRYSTALS PROPERTIES
short and well colored prisms
crystals system
orthorhombic
OTHER INFORMATIONS
Astrological sign
Gemini, Libra, Pisces
APPROACHING GEMS
Exploited
sites
It is widespread in the gneisses, in crystalline schists, in some granites but very rarely in beautiful crystals, only the transparent ones from Madagascar and Sri Lanka are considered gems.
use in jewelry
It is cut in the axis which reinforces the most its blue color, in rectangular shape as the emerald or oval or round faceted, but it is rarely used, it is mostly a collection stone. It has been called the “water sapphire” but this name is prohibited.
Iolite is the stone of the 21st anniversary year of marriage.
Daily care
and precautions
Although of a good hardness, it is sensitive to shocks that can cause its cleavage. Not to put in contact with acids.
imitations and
treatments
Glass imitations exist. Its strong pleochroism can easily differentiate it from imitations.
Historical
healing properties
It would be a gem of spirituality, initiation, but softer than sapphire and tanzanite. Associated with the throat chakra and front, it would provide a strong link between the earthly anchor and the cosmic mind. It would be intuitive, would avoid evil thoughts that might lead to depression.
Other
Gems
Venez visitez
notre site web
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