Editing Metal (section)

===Base, noble, and precious metals===
{{main|Base metal|noble metal|precious metal}}
The term ''base metal'' refers to a metal that is easily [[oxidation|oxidized]] or [[corrosion|corroded]], such as reacting easily with dilute [[hydrochloric acid]] (HCl) to form a metal chloride and [[hydrogen]]. The term is normally used for the elements, and examples include iron, [[nickel]], [[lead]], and zinc. Copper is considered a base metal as it is oxidized relatively easily, although it does not react with HCl.

[[File:Rhodium powder pressed melted.jpg|thumb|[[Rhodium]], a [[noble metal]], shown here as 1&nbsp;g of powder, a 1&nbsp;g pressed cylinder, and a 1&nbsp;g pellet|alt=Rhodium powder, a rhodium cylinder, and a rhodium pellet in a row]]
The term [[noble metal]] (also for elements) is commonly used in opposition to ''base metal''. Noble metals are less reactive, resistant to [[corrosion]] or [[oxidation]],<ref>{{cite book |url=https://books.google.com/books?id=Tiv9Ba4dDI4C&q=Noble+metals+are+metals+that+are+resistant+to+corrosion+or+oxidation&pg=PA267 |title=Chemical Oxidation Applications for Industrial Wastewaters |last1=Tunay |first1=Olcay |last2=Kabdasli |first2=Isik |last3=Arslan-Alaton |first3=Idil |last4=Olmez-Hanci |first4=Tugba |date=2010 |publisher=IWA Publishing |isbn=978-1-84339-307-8 |language=en}}</ref> unlike most [[base metal]]s. They tend to be precious metals, often due to perceived rarity. Examples include gold, platinum, silver, [[rhodium]], iridium, and palladium.

In [[alchemy]] and [[numismatics]], the term base metal is contrasted with [[precious metal]], that is, those of high economic value.<ref>{{cite book |url=https://books.google.com/books?id=dWMqaOTqSqcC&q=A+precious+metal+rare+metal+of+high+economic+value&pg=PA203 |title=Earth's Natural Resources |last=Walther |first=John V. |date=2013 |publisher=Jones & Bartlett Publishers |isbn=978-1-4496-3234-2 |language=en}}</ref> Most coins today are made of base metals with [[fiat currency|low intrinsic value]]; in the past, coins frequently derived their value primarily from their [[precious metal]] content; [[gold]], [[silver]], [[platinum]], and [[palladium]] each have an [[ISO 4217]] currency code. Currently they have industrial uses such as platinum and palladium in [[catalytic converters]], are used in [[jewellery]] and also a role as investments and a [[store of value]].<ref>{{cite book |url=https://books.google.com/books?id=qaBmBgAAQBAJ&q=The+demand+for+precious+metals+is+driven+not+only+by+their+practical+use%2C+but+also+by+their+role+as+investments+and+a+store+of+value&pg=PA105 |title=The Art of RF (Riba-Free) Islamic Banking and Finance: Tools and Techniques for Community-Based Banking |last=Abdul-Rahman |first=Yahia |date=2014 |publisher=John Wiley & Sons |isbn=978-1-118-77096-2 |language=en}}</ref> Palladium and platinum, as of summer 2024, were valued at slightly less than half the price of gold, while silver is substantially less expensive.