Iolite
According to legend, Vikings used iolite slices to reduce glare when checking the sun’s position. Known in the jewellery trade as Iolite, this mineral is known as cordierite to geologists and mineralogists. It was named after French mineralogist Pierre Cordier.
Birthstones & Anniversaries
Iolite is the gemstone for the twenty-first wedding anniversary.
Facts
Mineral: Iolite (Cordierite)
Chemical composition: Mg2Al4Si5O18
Colour: Violetish blue (pleochroic colourless-yellow)
Refractive index: 1.542 – 1.551
Birefringence: +0.045, -0.011
Specific gravity: 2.61
Mohs hardness: 7.0 – 7.5
