Iolite / cordierite pleochroism in polarized light

Iolite / cordierite in polarized light (a computer screen). The light is polarized horizontally. The strong pleochroism of corderite shows up here as the transparency and color of the stone varies with its orientation. According to an old saga, the Vikings used a "sun stone" to help them find the sun behind the clouds during their navigations. Some people believe this "sun stone" was, in fact, cordierite.

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• #cordierite
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