noble metal

Faberge egg

Precious metals often occur as the free elements in nature. Not only gold and silver, which for centuries have been used in jewelry and ornamentation, such as this Fabergé egg, but others such as platinum and iridium also come into this category. Silver and mercury are borderline cases. Mercury, for example, occurs as its sulfide but heating releases the metal, which readily alloys with other metals.

A noble metal is any of the unreactive, corrosion-resistant precious metals, comprising the platinum group, silver and gold, and sometimes rhenium.