... transparent crystal state2.hardness 7.8, specific gravity 4.6-4.71, 1.93-2.01 refra Country of ... brown and other colors, hardness 7.8, specific gravity 4.6-4.71, 1.93-2.01 refractive index, birefringence, ... (spongeZr) and zirconium compounds (zirconium dioxide, zirconium oxychloride, zirconium, sodium fluorozirconate, potassium, zirconium sulfate, etc.). High quality Zirconium Sand with best price