Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. metal
8. [metal by quality]

Anotations

Scope note:

Metal or alloy that is resistant to oxidation, corrosion, and dissolution by acids. Noble metals remain bright when heated in air. Examples of noble metals are gold, iridium, mercury, osmium, platinum, and ruthenium. In physics, noble metals are restricted to those having filled electronic d-bands: according to this definition in physics, only gold, silver, and copper are noble metals. Many noble metals are also precious metals, due to their rarity in the Earth's crust.