The refractive index of turquoise varies from 1.61 to 1.65 on the three crystal axes, with birefringence 0.040, biaxial positive, as measured from rare single crystals.
The refractive index of turquoise varies from 1.61 to 1.65 on, the three crystal axes with birefringence 0.040, biaxial positive, as measured from rare single crystals.