A "clear" S mintmark is one where the "S" is very distinguishable. The "filled" S mintmark is one where the "S" is more blob like (it looks more like an 8 than an S)
For the type I the mintmark is filled and the type II the mintmark is clear.
It's is a well defined, very identifiable mintmark.
The mintmark is very sharp, clear and distinct. In simple terms it looks good.
A coin with an S mintmark means is was made at the San Fracisco Mint.
The 1981 Proof set has a current value of $8.00. The issue price was $11.00. Check the "S" mintmark on all the coins, on most of the sets the mintmark is filled an does not appear well defined. If all coins have a sharp clear mintmark, value may be $300.00 or more.
Look on the back below the DO in DOLLAR. It could be black or there could be a small O, S, or CC mintmark. Value as of June 2012: No mintmark:$52 "O" mintmark:$156 "S" mintmark:$52 "CC" mintmark:$540
While 1910 is not a rare date for Barber dimes, it is silver, so at a minimum it has a current silver value of about a dollar. You also need to check the back, near the bottom, for a mintmark. There may be a "D" or an "S" there. With full rims on both sides, and an "S" mintmark, it's worth about $3.00 If all the letters of LIBERTY on the headband are readable, then with no mintmark it's worth $2, with a "D" mintmark it's worth $6, or with an "S" mintmark it's worth $35 If all the details are strong, with only a slight amount of visible wear, then with no mintmark it's worth $15, with a "D" mintmark it's worth $35, or with an "S" mintmark it's worth $80 If your coin is a nice uncirculated example, then with no mintmark it's worth $75, with a "D" mintmark it's worth $150, or with an "S" mintmark it's worth $300
The mintmark will be on the reverse of the coin under the wreath. The mintmark will either be a D or S or may have no mintmark, in the case of a coin with no mintmark it was minted in Philadelphia.
For a Lincoln cent, any mintmark is under the date on the obverse. Indian Head cents have the mintmark on the reverse under the wreath and can only be an "S" mintmark, on just on the 1908 & 1909 issues.
The mintmark is very clear compared to the type-1, that's why it's more valuable.
If it is a "s" quarter it will always have the S mintmark. You can find this mintmark usually on the back of the coin. The exact location will depend on the type of quarter.
It's simple. A 1922 S silver dollar will have a S mintmark while a 1922 D silver ill have a D mintmark. The mintmark is located on the reserve below the word "ONE".