If you mean the mark to the left of the W then it is just damage. It’s the impact of the reeded edge of another coin on the surface of this one. You’ll see this kind of mark on a lot of coins.
TurtleCat Gold Dollars
Read through other posts on this forum concerning "errors". You will find that most finds by new collectors are nothing more than damage from circulation or abuse. You will also be able to determine which are genuine mint "errors" or varieties. The coins with damage will just be worth face value. Some of the genuine "errors" or varieties will command a premium from some collectors though only major errors will command significant premiums.
Thank You for the information, most appreciated.
And please feel free to participate here as well. Lots of cool threads and lots to learn.