When a coin has a O mintmark it means it was made at New Orleans. This mint is no longer in operation.
In the United States there were 4 operating mints in 1878. 1. Carson City, Nevada identified by the mint mark "CC" 2. New Orleans, Louisiana identified by the mint mark "O" 3. Philadelphia, Pennsylvania identified by no mint mark so all coins without a mint mark were minted in Philadelphia. The mint mark "P" has been on coins minted since 1968. 4. San Francisco, California identified by the mint mark "S".
The "O" mintmark identifies the Mint at New Orleans, LA
The mint mark is below the date.
No - there are three types ... 392,021,000 with no mint mark 57,154,000 with D mint mark 57,154,000 with S mint mark for 1919 USA 1 Cent. The mint mark (if present) is below the date.
No mint mark means it was minted in Philadelphia.
The mint mark is located on the reverse [tails] side of the coin at the bottom below the wreath. If there is no mint mark then the coin was minted at the Philadelphia Mint.
The first Half dollar with any mint mark was from the New Orleans Mint in 1838.The mint mark is on the reverse under the eagle
There is not always a mint mark on coins. If your coin does not have a mintmark it means that it was made at the Philadelphia mint in Pennsylvania.
A mint mark tells where the coin was minted, for example, a P mint mark (or in some cases no mint mark) signifies the coin was minted in Philadelphia, D is for Denver, S is for San Fransisco. I'm assuming someone told you that the mint mark was under the eagle for whatever coin you had, so you simply need to look under the eagle to find a mint mark. Keep in mind that some coins were produced in the Philadelphia mint and have no mint mark.
Not enough information. You have its condition identified but not its date or mint mark. Please post a new question with those important facts.
The mint mark of the Denver Mint (shown as a "D") and the San Francisco Mint (shown as "S) on the Eisenhower Dollar is located on the obverse (heads) side of the coin directly beneath the bust of Eisenhower. If there is no mint mark there, then the coin was struck at the Philadelphia Mint and in this mint did not place a mint mark on the coins struck there until 1979.
There is no mint mark on the 1921 Peace dollar because they were all minted in Philadelphia and thus carry no mint mark.