Zirconium is a metal with the symbol Zr and the atomic number 40. It is a lustrous, gray-white, strong transition metal that resembles titanium and is very corrosion resistant. Zirconium is obtained mainly from the mineral zircon. The leading use is in nuclear reactors, especially in the cladding of the fuel rods, due to its low neutron-capture cross-section and its resistance to corrosion. Other uses are in opacifiers, sandblasting media and in welding rod coatings.