The average cost of zirconium is $25 per kg. The prices of zirconium depend on the chemical purity (common zirconium, nuclear grade, reagent for analysis) or the form (sponge, powder, ingots). It is a lustrous, gray-white, strong transition metal that resembles titanium. It is never found as a native metal and obtained mainly from the mineral zircon, which can be purified with chlorine. It has no known biological use and because of its high resistance to corrosion, zirconium is often used as an alloying agent in materials that are exposed to surgical appliances, explosive primers and filaments.