Zirconium (Zr) is a metallic chemical element with atomic number 40. It has five naturally occurring isotopes, of which ⁹⁰Zr (40 protons, 50 neutrons) is the most abundant. It accounts for more than half the zirconium found in nature.

Zirconium is sometimes used in abrasives like sandpaper, and also sometimes in dental implants.