🍋 Citrine Optics Lab: Refractive Index 1.544-1.553, Dispersion and Brilliance of a Cut Citrine

Citrine (SiO2 with Fe3+): refractive index 1.544-1.553, Mohs hardness 7, dispersion 0.013. Citrine is yellow to orange-brown quartz coloured by iron (Fe3+). Like amethyst it has Mohs hardness 7 and a refractive index of about 1.55, and it is tough enough for everyday wear.