Discolouration of a metal surface due to the formation of a thin film of oxide, sulphide or some other corrosion product. Used most often to describe the black corrosion product that forms on silver.
![](https://aiccm.org.au/wp-content/uploads/2008/03/Tarnish.jpeg)
Discolouration of a metal surface due to the formation of a thin film of oxide, sulphide or some other corrosion product. Used most often to describe the black corrosion product that forms on silver.