Zinnwaldite and Cordierite Iolite Optic Character
Zinnwaldite and Cordierite Iolite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Zinnwaldite and Cordierite Iolite Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Zinnwaldite and Cordierite Iolite optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character. Cordierite Iolite has Biaxial/+ character.