The chemical composition of crystal is pure silica with a specific gravity of 2.66, which is very stable. I motsetning til andre edelstener, which contain many other elements or contained substances, the specific gravity will be in a range. Its refractive index is 1.544～1.553. , The birefringence difference is 0.009, spredningshastigheten er 0.013, og den [...]
