Precious Metals
A metal is considered precious because of its rarity and beauty. Chemically, the precious metals are less reactive than most elements, have high luster, are softer or more ductile, and have higher melting points than other metals, thus 
making them well suited for decoration and commerce. Historically, precious metals were important as currency, but are now regarded mainly as investment and industrial commodities. Gold, silver, platinum, and palladium, the primary precious metals, each have an ISO 4217 currency code.
