description Iolite Overview
Iolite is the gem variety of cordierite, a magnesium- and aluminum-bearing silicate mineral that commonly appears blue, violet-blue, or grayish. It is strongly pleochroic, meaning that its apparent color changes when viewed from different directions, so careful cutting is important. Iolite is used in jewelry and is associated with the historical claim that Viking navigators used clear cordierite crystals as polarizing filters to locate the sun through cloud or haze.
help Iolite FAQ
What is iolite?
Iolite is the gem variety of cordierite, a magnesium- and aluminum-bearing silicate mineral. It commonly appears blue, violet-blue, or grayish.
Why does iolite change color when viewed from different directions?
Iolite is strongly pleochroic, meaning its apparent color changes with viewing direction. This optical property makes careful cutting important for showing its best color.
What colors can iolite be?
Common colors include blue, violet-blue, and grayish tones. The visible color can shift because of iolite's strong pleochroism.
Is iolite the same mineral as sapphire?
No. Iolite is the gem variety of cordierite, while sapphire is a variety of corundum. They can both appear blue, but they are different minerals.
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