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www.mineralgallery.co.za Minerals F-J
The same stone viewed from two different sides showing the strong pleochroism in iolite. |
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Iolite |
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Name
Iolite
Chemistry
Uses
As a gemstones
Color
Different shades of blue
Hardness
7.5
Specific gravity
2.57-2.66
Iolite is also known as cordierite or 'water saphire'. It is a silicate of aluminium, iron and magnesium. Good specimens have a very pleasing colour showing very marked pleochroism from blue to grey when turned through the right angle.
Because of the scarcity of good gem material, there is a constant demand for specimens and cutting quality stones. Although the stone has the right colour for a sapphire it lacks the brilliance and sparkle of a true sapphire.
The crystal system is orthorhombic or massive, often scaly or granular.