... , red, brown and other colors, hardness 7.8, specific gravity 4.6-4.71, 1.93-2.01 refractive index, birefringence, absorb ... in the production of glass, metal (spongeZr) and zirconium compounds (zirconium dioxide, zirconium oxychloride, zirconium, sodium fluorozirconate, potassium, zirconium sulfate, etc.). 2012 HOT ...