A metallic element, constituting the most precious metal
   used as a common commercial medium of exchange. It has a characteristic
   yellow color, is one of the heaviest substances known (specific gravity
   19.32), is soft, and very malleable and ductile. It is quite
   unalterable by heat, moisture, and most corrosive agents, and therefore
   well suited for its use in coin and jewelry. Symbol Au (Aurum). Atomic
   weight 196.7.