first lets get straight that the "S" is for San Francisco NOT silver that is the US Mint facility that makes all proofs presently and the mint makes 2 types of proofs for the quarters clad and silver when you see copper on the side it is a clad. so you have a Montana clad proof minted at San francisco
now a proof coin is a coin made by the mint with extra care and special minting to give the coin the best finish that can notice the shine in the field and compare that to a normal coin.
handy tip on the left side of the forum there is a glossary it sez a proof is .....
Proof
A coin usually struck from a specially prepared coin die on a specially prepared planchet. Proofs are usually given more than one blow from the dies and are usually struck with presses operating at slower speeds and higher striking pressure. Because of this extra care, Proofs usually exhibit much sharper detail than regular, or business, strikes. PCGS recognizes Proofs (PR) as those struck in 1817 and later. Those coins struck prior to 1817 are recognized as Specimen strikes (SP).
<EDIT:>spellin</edit>
Edited by yotie
06/11/2011 7:18 pm