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'''Iridium''' is an [[element]] in the [[transition metal]]s class of the [[periodic table of the elements|periodic table]].  It is hard and lustrous, and is perhaps the most corrosion-resistant metal known.  It has the second-highest density of all elements, after [[osmium]].

'''Iridium''' is an [[element]] in the [[transition metal]]s class of the [[periodic table of the elements|periodic table]].  It is hard and lustrous, and is perhaps the most corrosion-resistant metal known.  It has the second-highest density of all elements, after [[osmium]].

An alloy of [[platinum]] and iridium was used in the international standard [[International_System_of_Units#Meter|meter]] bar, before the standard was changed in 1960.  A similar alloy is still used in the international standard [[International_System_of_Units#Kilogram|kilogram]].  An alloy of 90% [[platinum]] and 10% iridium is widely used in both the jewelry and chemical industries, because it is strong, hard, beautiful, and impervious to almost all chemicals even at very high temperatures.

An alloy of [[platinum]] and iridium was used in the international standard [[International System of Units#Meter|meter]] bar, before the standard was changed in 1960.  A similar alloy is still used in the international standard [[International System of Units#Kilogram|kilogram]].  An alloy of 90% [[platinum]] and 10% iridium is widely used in both the jewelry and chemical industries, because it is strong, hard, beautiful, and impervious to almost all chemicals even at very high temperatures.

A layer of iridium in certain rocks, found all over the world, is part of the evidence implying that an asteroid strike caused the [[Cretaceous-Tertiary Mass Extinction]].  

A layer of iridium in certain rocks, found all over the world, is part of the evidence implying that an asteroid strike caused the [[Cretaceous-Tertiary Mass Extinction]].  

==See Also==

==See also==

* [[Precious metal]]

* [[Precious metal]]

* [[Gold]] and [[Silver]]

* [[Gold]] and [[Silver]]

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{{Periodic table}}

[[Category:Elements]]

[[Category:Elements]]

[[Category:Metals]]

[[Category:Metals]]

[[Category:Precious Metals]]

[[Category:Precious Metals]]