How come some silver is shiny and some is dull?

Question

How come some silver is shiny and some is dull?

Answer 1

Some is polished, some is not

Answer 2

Silver interacts with air and water and bonds with the oxygen, or oxidizing.  In silver, this is called tarnishing.  In iron, it's called rust.  In aluminum it's called oxidation.  In copper, it's also called tarnishing.  If you remove the outer layer it will become shiny again until it again becomes oxidized.  Don't polish your silver if you want it to retain its value, particularly coins.  Every time you polish it you remove some of the silver.

Answer 3

Many years ago before your time we used to take mercury and rub it on silver coins.