1. Symbol Pt A silver-white metallic element occurring in alluvial deposits in sperrylite and nickel ores, 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 1,768.2°C; boiling point 3,825°C; specific gravity 21.45 (20°C); valence 2, 3, 4. See Periodic Table.

2. A medium to light gray.