P L A T I N A

plat·i·num n. Symbol Pt A silver-white metallic element occurring worldwide, usually mixed with other metals such as iridium, osmium, or nickel. It is ductile and malleable, does not oxidize in air, and is used as a catalyst and in electrical components, jewelry, dentistry, and electroplating. Atomic number 78; atomic weight 195.08; melting point 1,772°C; boiling point 3,827°C; specific gravity 21.45; valence 2, 3, 4. See table at element. A medium to light gray. [New Latin, from Spanish platina, platinum. See platina.]